TEXAS AGRICULTURAL EXPERIMENT STATION A. B. CONNER, DIRECTOR College Station. Texas BULLETIN NO. 630 APRIL 1943 VITAMIN A STUDIES IN FATTENING FEEDER CALVES AND YEARLINGS J. H.- JONES, H. SCHMIDT, R. E. DICKSON, G. S. FR-APS, J. M. JONES, J. K. RIGGS, A. R. KEMMERER, P. E. HOWE, W. H. BLACK, N. R. ELLIS, AND PAUL T. MARION Division of Range Animal Husbandry and Bureau of Animal Industry, United States Department of Agriculture, Cooperating LIBRA Agriculturalwisstamiaai 3a§i.@;ge="i'ae1as, AGRICULTURAL AND MECHANICAL COLLEGE OF TEXAS T. O. WALTON, President "I f; B35——443-51\i[-L180 It has been shown in vitamin A studies in fattening feeder cattle that fattening rations may sometimes be deficient in vitamin A. Vitamin A deficiency is characterized by night blindness. In late!‘ stages the cattle become less alert, may water at the eyes, show nasal discharge, suffer from solar heat, show body swelling, become day blind, lose appetite and Weight, develop rough, dry hair coat, and die unless the condition is relieved. ' Farm animals are supplied vitamin A largely through carotene in grasses, hays and silage. Carotene is formed only in plants and is asso- ciated with green color. Grazing animals are able to change carotene to vitamin A which process takes place in the liver. Green grasses and legumes, leafy green new crop legume hays, and cod or other fish liver oil, all high in vitamin A potency, will protect fattening cattle from vitamin A deficiency or will remedy the condition if it has been all0W€d to occur. a The vitamin A and carotene content of the liver, blood and fat is related to the quantity of carotene in the feed and the length of time such feed has been consumed; Feeder cattle removed from dry range during droughts become depleted of vita-min A reserves more quickly than those removed from green range. Young animals become depleted more quickly than older ones from the same range. Carotene in the ration has no effect upon gain or fattening as long as there are body reserves of carotene and vitamin A, nor does an abundance of carotene increase gain after the minimum amount required to main- tain health is fed. The minimum of carotene for the maintenance of health was approximately 2000 to 2500 micrograms daily per 100 POUTIGS live weight although 1500 nlicrograsms allowed satisfactory fattening of the steers in spite of minor symptoms of vitamin A deficiency. In dry lot fattening with mixtures of protein supplements, grains, cot- tonseed hullls or weathered roughages, carotene supplements are usually not needed for the first 50 to- 100 days. To guard against. losses from vitamin A deficiency one can observe the cattle for night blindness after 50 days. If night blindness is observed the cattle may be fed 1 to 3 pounds of good green alfalfa hay or other green roughage per Ahead daily, or instead of waiting for the onset of night blindness feed 1 to 2 pounds of alfalfa from the start. CONTENTS Page Introduction __ _ __ 5 Procedure ______ ____ 5 Cattle Used ______________________________________________ __ _ _ 5 Feeds Used __________________________ __ _ 7 Method of Feeding and Treatment __________________________________________________ __ 3 Measure of Night Blindness - __ - 9 General Manifestations of Vitamin A Deficiency in Fattening Cattle---_ 9 SYIIIDtOIIIS and Gross Pathology of Vitamin A Deficiency __________ __ 9 Effect of Long Continued Feeding on Low Carotene Level ______ __ 13 Effect of Various Treatments ______________________________________________________ __ 15 Time Required for Depletion of Body Reserves of Vitamin A in Feeder Cattle in Dry Lot _ _ _ _ _ _ _ _ _ _ _ _ , _ _ _ _ _ _ _ _ _ _ _ _ _ __ _ 19 Effect of Quantity of Carotene Upon Night Blindness and Related Symptoms of Vitamin A Deficiency .......................................... _- 22 Effect of Quantity of Carotene Upon Gain and Feed Consumption of Fattening Cattle _ ___ 32 Relation of Quantity of Carotene to Carotene and Vitamin A Content of Livers, Blood Plasma, Fat and Lean Tissue __________________________ __ 40 Carotene and Vitamin A Content of Livers .................................. -_ 41 Carotene and Vitamin A Content of Blood Plasma ______________________ -_ 42 Carotene and Vitamin A Content of Fat and Rib Cuts .............. -- 45 Conditions Under Which Vitamin A Deficiency May Occur ................... -_ 46 Summary and Conclusions 49 Literature Citedp- - ................ _- 52 VITAMIN A STUDIES IN FATTENING FEEDER CALVES AND YEARLINGS J. H. Jones‘, H. Schmidt’, R. E. Dicksoni, G. S.Frap-s", J. M. Jones5, J. K. Riggs“, A. R. Kemmerer’, P. E. Howei, W. H. Black”, N. R. Ellis“, and Paul T. Marion“ Texas Agricultural Experiment Station and Bureau of Animal Industry, United States Department of Agriculture, cooperating. Vitamin A is recognized as one of the essential vitamins necessary for the maintenance of life. Plants furnish it to animals in the form of carotene, a precursor of vitamin A. Insufficiency of vitamin A, when continued long enough, leads to serious disturbances of health, blindness, or even death. Figure 1 shows a steer which was fed a ration deficient in carotene until seriously affected by vitamin A deficiency. The steer became permanently blind but re- gained good condition when al- falfa, which supplies carotene, was added to his ration. Disorders in fattening cattle, now known to be caused by vita- min A deficiency, were described before that vitamin was discov- ered. Such disorders were once associated with the use of rations in which 'pr0tein Supplements Figure 1. This steer, although remain- were fed without grain along with 111g‘ totally blind as; a» result of vitamin A deficiency, re- iroughages of poor quality. Among gained good condition upon - - - being supplied with carotene early investigators to study this in dehydrated alfalfa leaf problem were Connell and Car- meal. son (1), Burns and Metcalfe (2), and'Curtis (3) and (4). It was not until 1930 that Halverson ‘and Sherwood (5), collaborators of Curtis in the work started at the North Carolina Station (3) in 1908, reported work showing that the major factor involved in injury to steers fed long periods in dry lot on cotton- seed meal and cottonseed hulls was a vitamin A deficiency. This was ‘Animal Husbandman, TAES. zChief, Division of Veterinary Science, TAES. aSuperintendent, Substation No. 7, Spur, Texas, TAES ‘Chief, Division of Chemistry, TAES. “Chief, Division of Range Animal Husbandry, TAES. “Associate Professor in Animal Husbandry, Formerly Assistant Animal Hus- bandman, TAES. ‘Chemist, TAES. sAssistant Chief, Bureau of Animal Industry, USDA. “Senior Animal Husbandman, Beef Cattle Investigations, BAI, USDA. “Acting in Charge, Animal Nutrition Investigations, BAI, USDA. Ulligniinal )Husbandman, Substation No. 7, Spun, Texas, TAES, (On leave in . . rmy . 6 BULLETIN N0. 630, TEXAS AGRICULTURAL EXPERIMENT STATION confirmed by this Station with an experiment started in 1934 and first reported (6) (31) in 1935. That experiment and succeeding experiments are now presented although reports on different phases of the study have been published (7) (8) (9) by the Texas Station Workers. The work reported here was planned in cooperation with the Bureau of Animal Industry, U. S. Department of Agriculture, in 1935, following the completion of a feeding test begun in November, 1934. In that test, hereafter referred to as Experiment 1, a group of weaned steer calves were fed on a ration consisting of cottonseed meal, white grain sorghum grain and cottonseed hulls; while other groups were fed the same mixture of feeds with the addition of various amounts of ground alfalfa hay. The following spring a group which did not receive alfalfa developed disorders which Schmidt (9) found to be caused by vitamin A deficiency. The groups which received alfalfa did not develop such disorders. The experiments were planned to determine: (1) the quantity of carotene required in fattening feeder/calves and yearlings, (2) the con- ditions under which vitamin A deficiency may occur, and (3) practical means of prevention and correction of such deficiency in fattening cattle. PROCEDURE Except in the first experiment the general plan was to feed a ration low in carotene until night blindness occurred and then to feed, upon the basis of body weight, supplementary test levels of carotene supplied by ground alfalfa hay or dehydrated alfalfa leaf meal. This method of feeding carotene according to body Weight was based upon the hypothesis advanced in 1935 by Guilbert and Hart (10), that the vitamin A require- ment is proportional to body weight. The above plan provided for two rather distinct periods of feeding: (1) the period of depletion of body reserves of vitamin A, and (2) the period of testing the levels of carotene. The rations fed during the period required for depletion of body reserves of vitamin A, as indicated by the occurrence of night blindness, were calculated to maintain good condition and rate of gain without producing finish. The depletion period was used to equalize, insofar as possible, the individual body reserves of vitamin A prior to the test) period. After depletion, grain was added to the rations in quantities sufficient for the production of marketable finish. Cattle Used Ten separate groups of feeder cattle comprising 370 head have been used. They were, in the main, Good to Choice Hereford feeders taken directly from ranges in Dickens County to the feedlots at Substation No. 7, Spur, Texas. Although several days usually passed between the date the cattle were received and the date the experiment was started they were, in all instances, maintained on rations low in carotene during such periods. With the exception of one group of calves obtained in March and another group in September, the cattle were received about November 1. Table 1 lists the cattle used. VITAMIN A STUDY IN FATTENING FEEDER CAL-VES AND YEARLINGS 7 Table 1. Feeder cattle used in these experiments No. Age Average! Date * Days of} Date Expt. of ; in initial of Prel. Test No. Year animals‘, Class months weight delivery Feeding Started ' pounds 1 ; 1934-25 i 4o 1 Steer calves _____ __ as 40c Nov. 2,1934 3e Dec. 5,1934 2 1 1935-36 1 48 ; Steer yearlings____ 16 559 Oct. 15, 1935 30 Nov. 14, 1935 3 1 lfi-ST g 50 1 Steer calves _____ -- 6-8 469 Nov. 23, 1936 16 Dec. 9, 1936 4 1937-38 1 50 ; Steer calves _____ -- 6-8 448 Nov. 12, 1937 6 Nov. 18, 1937 _ 5 ‘ 1938-39 ‘ 50 1 Steer calves__-_I_-_ 6-8 464 . Nov. 7, 1938i 24 Dec. 1, 1938 6 1939-40 I 40 i Heifer calves ____ __ 4-6 330 ‘ Oct. 25, 1939 28 Nov. 22, 1939 7 1940-41 50 i Steer calves _____ _- 4-6- 2 Sept. 9, 1940 9 Sept.18, 1940 8* 1938-39 1 10 i Steer calves _____ __ 4-6 289 Oct. 28, 1938 __ Oct. 28. 1938 9* 1939 12 f Steer calves _____ __ 3-5 2-46 Mar. 17, 1939 __ Mar. 17, 1939 10* 19119-40 ' 20 , Steer calves _____ __ 3-5 225 Oct. 25, 1939 -_ Oct. 25, 1939 *Used in study of time required for depletion only. Feeds Used The feed mixtures for both depletion and fattening are shown in Table 2. ‘ Table 2. Percentage composition of low-carotene feed mixtures used Composition of rations per cwt. Experiment Cottonseed Cottonseed j Sorghum Sorghum No. Year meal nulls grain Tankage fodder Depletion rations 1 1934-35 11 78 11 __ _- 2 1935-36 12 88 __ -- __ 3 1966-37 10 87 __ 3 __ 4 1937-38 10 87 -- 3 _.. 5 1938-39 10 87 __ 3 __ 6 1939-40 15 52 301* 3 __ 7 1940-41 10 69 18* 3 _- 8i 1938-39 13 __ 38* __ 49 9+ , 1939 12.5 62.5 25* __ -_ 1m 1939-40 15 _- 28* -- 57 , Fattening rations 1 19134-35 11 78 11 __ -_ 2 * 19315-36 15 55 30 __ -. s i 1936-27 1s 52 a0 s -_ 4 , 1937-38 15 52 30 3 __ 5 1 1938-39 15 52 30 3 __ 6 1989-40 15 35 - 45* 3 __ 7 \ 1940-41 15 43 38* 3 __ , Q ‘Fed ground milo heads. {Used in study of time required for depletion only. The 43% protein cottonseed meal and the cottonseed hulls used were of prime quality and were purchased locally. The tankage which was fed was newly processed 60% protein digester tankage. The ‘ground threshed grain sorghum grains fed in Experiments 1, 2,‘3, 4 and 5 and ground milo heads fed in Experiments 6, 7, 8, 9 ‘and 10 were of 8 BULLETIN NO. 630, TEXAS AGRICULTURAL EXPERIMENT STATION good quality and were locally produced. These grains, ranging in caro- tene content from 0.3 to 0.69 microgram per gram, supplied small amounts of carotene when fed in large quantities. Ground alfalfa hay, also'of local origin, was used to supply carotene in the first four experi- ments; but dehydrated alfalfa leaf meal was used in the succeeding experiments. Curative agents, as cod liver oil, pure crystalline carotene dissolved in maize oil, fresh green alfalfa, and fresh green sudan grass were used in instances of advanced vitamin A deficiency in Experiments 1 and 3. Cottonseed hulls were used as the sole roughage in all test rations except in Experiments 8 and 10 in which sorghum fodder having a carotene contentof about 4 micrograms per gram was used and in Experiment 9 in which sorghum fodder containing 2 micrograms of caro- tene per gram was fed during the first 58 days. Methods of Feeding and Treatment All of the principal feeds were mixed together on the percentage basis shown in Table 2. The mixtures were fed twice daily in the amounts that would be consumed. Pulverized limestone was fed at the rate of 0.10 pound per head daily in Experiments 3, 4, 5 and 7. Salt was fed free choice except in Experiment 6 in which 1 percent of salt was added to the feed mixture. During the depletion period the cattle were group fed except in Experi- ment ‘6 in which they were individually fed. In all experiments except the first they were individually fed during the fattening or test period in which the various carotene levels were supplied. In Experiment 1, all lots except one received ground alfalfa and all lots received grain from the outset. In the second and third experiments the cattle were placed in individual pens and were started on a fattening grain ration and a given carotene level as they successivelyireached depletion. In Experiments 4, 5, 6 and 7 the first cattle to become depleted were placed upon a carotene level of 800 micrograms per 100 pounds live weight daily until a sufficient number became depleted to form the various test groups. The fattening rations and the given carotene levels were then begun for all animals at the same time. Except for Experiment 1, alfalfa meal or dehydrated alfalfa leaf meal was fed to supply a stated number of micrograms of pure carotene per 100 pounds live weight daily. The carotene level was kept adjusted to the live weight by means of weekly weighings of the animals and weekly or bi-weekly determinations of the pure carotene content of the alfalfa. The carotene content of the alfalfa was reported in parts per million. The allowance of alfalfa for each animal was weighed daily to the nearest gram. In order to insure complete consumption, the alfalfa was fed with about 2 pounds of the regular feed mixture early in the morning, and when it had been cleaned up the balance of the morning feed was given. I VITAMIN A STUDY IN FATTENING FEEDER CALVES AND YEARLINGS 9 Measure of Night Blindness Since night blindness is the first noticeable symptom to develop in the syndrome of vitamin A deficiency this symptom was used as a guide in determining when the animals were depleted of their body reserves of vitamin A. Two consecutive observations of a recognizable degree of night blindness or other definite assurance of vitamin A deficiency were considered evidence of depletion. In a few cases the observers-were unable to determine the degree of night blindness but other symptoms afforded evidence of depletion. The animals were tested for night blindness out-of-doors after twilight by driving them back and forth through 8-foot alleys in which were located movable panel barriers of wood either unpainted or painted black on one side and white on the other. With continued depletion the animals appeared to become progressively more night blind, finally becoming completely night blind in nearly all cases. As a result, night blindness or affected night vision was measured by the judgment of the observer and expressed in degrees as follows: 0—normal, no indication of defective night vision; 1<>—-cautious, but can see objects at least 5 feet away; 2°—cautious, but can see objects 2 feet away; 3°——totally night blind. The reaction of night blind cattle to different intensities of light was observed on numerous occasions by using a flood light controlled with a theatre dimmer; however, this light was not used in routine testing. Animals which were completely night blind were able to find their way with little difficulty when the light was too dim to be measured by a Westonphotographictlight meter and when it appeared as only a low orange-red glow on the ground. Moonlight apparently did not particu- larly aid the night blind cattle t0 see but flashes of lightning aided vision and affected the accuracy of routine night blindness tests. The different years of work identified as separate experiments are mentioned only as the results from them contribute to the principal findings. Attention has been given to the general manifestations of vitamin A deficiency in fattening cattle, the time required for depletion of body reserves of vitamin A, and the effect of feeding various carotene levels upon night blindness, health, gain and the carotene content of livers, blood plasma and fat. GENERAL MANIFESTATIONS QF ‘VITAMIN A DEFICIENCY IN FATTENING CATTLE Symptoms and Gross Pathology of Vitamin A Deficiency On a ration deficient in vitamin A and after the depletion of body reserves of vitamin A, symptoms of vitamin A deficiency appear and gradually progress in severity until death occurs. The first indication‘ of a vitamin A deficiency in cattle is the appearance of night blindness. When checking the cattle in semi-darkness one will observe as a rule that the animal when approaching an obstacle will suddenly stop and veer ‘ fected eye __or eyes with a maximum‘ dilatation of the_ pupil. ~ fed a ration low in carotene during the winter of 1934-35. 1o BULLETIN N0. 63o, TEXAS AGRICULTURAL EXPERIMENT STATION in order to avoid it. It acts as though it had suddenly discovered the obstacle, although normally it should have recognized it from a much greater distance. As timegoes on this night blindness becomes gradually and progressively intensified until the animal becomes totally blind. Low degrees of night blindness may be present and continue for sev- eral weeks during which time the actual degree is difficult to deter- mine, but sooner or later the condition will progress to total night blindness perhaps within as short a time as one week. At this stage the animal shows normal vision during the day but if carotene is not supplied the condition may progress to so-called day blindness in one or both eyes and manifested by total permanent blindness in the af- p In cases of permanent blindness in both eyes the animal shows a characteristic cau- tious walk in which the nose is carried higher and a little more forward than normally, see Figure 1, often with audible breathing as though the animal were sniffing the breeze. In case blindness is present only in one eye, the head is held in a peculiar “cocked” position, see Figure 2, with the blind eye side tilted slightly upwards. Symptoms we now consider as due to vitamin A deficiency were observed in ancient times. Thus the statement (11) “and the wild asses did stand in the high places, they snuffed up the wind like dragons; their eyes did fail;_ be- cause there was no grass” is pecu- liarly descriptive of a ’vitamin A deficiency. An involvment of the eye was recognized in the condi- tion known as ‘fgfqgtggsickne-ss” by Connell and Carson (1). Curtis (3) listed the symptoms observed in some cattle fed only cottonseed meal and cottonseed hulls as: affected eyesight, temporary or possibly permanent blindness, weakness followed by staggers, fits or spasms‘, swellings, failure of conception and respiratory troubles. Guilbert and Hart (10) observed the occurrence of blindness among cattle fed diets deficient in carotene and found night blindness to be the first detectable symptom of vitamin A deficiencfi Many other workers have reported upon the involvment of the eye in vitamin A deficiency as Moore (12). Figure 2. Steer 80 from Experiment 3. permanently day blind in left eye. Note abnormal carriage of the head. I Hale (13) (14) established the fact that maternal vitamin A deficiency may result in a variety of defects in the offspring, including abnormally small eyes at birth and, with other Texas workers, observed such small eyes among pigs and calves born under farm conditions following the severe drouth of 1934. In one particular dairy herd the dry cows were Ten of the 15 calves dropped in the spring of 1935 were blind. VITAMIN A S'l"IjDY 1N FATTENING FEEDER CALVES- AND YEARLINGS 11 Before the stage of day blindness is reached the eyes usually show other affections such as watering, Figure 3, with or without inflam- matory signsof the mucous membranes and the cornea may and often does show opacity. This opacity varies markedly in extent and degree, usually beginning with one or two whitish specks the size of a pin head and may progress until the whole cornea is involved and ulceration sets in. In the early stages of opacity no inflamma- tory reaction is present, but as the condition progresses such re- action sets in and may become quite intense and the eyes pro- trude more than normally. Such opacities of the eyes are especial- ly prevalent in calves and year- lings and may be entirely absent in mature animals". Following the onset of night blindness a lack of normal alert- ness, Figure 4, is usually one of» the early symptoms that can be* observed. At this first stage of droopy condition the animal does not necessarily go off feed or show other marked evidence ‘of vitamin A deficiency. 1 L taken; however, day blind- Convulsions is one of the sym-p- f iaffiiwagfigh ‘gt, cxgflfiiisgfifly toms observed in many cases and sometimes appears before affection of the eye becomes noticeable or be- fore any other symptoms, with the exception of night blindness, are pres- ent. They appear suddenly with or without apparent provocation. The animal suddenly sways or staggers, Figure 5, for a few seconds, drops to the ground and lies flat on its side with legs extended, the muscles rigid and breathing suspended. This seizure lasts for about one-half Amorther symptom of vita- Pigure 3. min A deficiency: swollen eyes with profuse lacrima- tion, also nasal discharge. Such eye cases may be c011- fused with infectious kerati- tis. This steer was day blind 2 weeks after the picture was minute when the animal suddenly lets out a long audible breath, relaxes“, its muscles and gets up as though nothing had happened. When the condition has progressed to the point of complete night blindness or affection of the eyes has set in, other symptoms become apparent such as a more or less marked nasal discharge and suffering from solar heat manifested by the saliva being beaten into a foam, which may drop to the ground in large quantities, and accelerated res- piration which may progress to panting with protruding tongue, Figure 6. This panting was observed only in the summertime during the heat of the day, even though’ the animal was in the shade. When during this time the animal is forced from the shade into the sun it makes frantic ef- forts to reach shade again. ~—_r1 a devoid of carotene. . 5 ...<..:~=~;: éthe limits of the hock and the foot. l2 BULLETIN NO. 630, TEXAS AGRICULTURAL EXPERIMENT STATION Edematous infiltration of the tissues also appears about this ,~time, which becomes visible ex- ternally in the form of swellings. These» are most readily recognized when the skin rests upon a. solid foundation such as bones or thin layers of muscles and thus first become manifest on the legs in region between the upper Naturally they may include any part of the body and may there- fore be seen in the region of the thigh, shoulder, and neck, Figure 7. These swellings do not nec- essarily remain uniform in extent and degree once they a-ppear but rather vary in intensity from day to day or week to week, especially when the ration is not completely A harsh, dry hair coat and an unpliable skin A may also develop. The s y m p t o m s enumerated above appear one after the other, sometimes r a p idly, sometimes slowly, but develop in intensity as the depletion of body reserves of vitamin A progresses. A serious I stage is finally reached, Figure 7, in which the animal refuses feed, loses weight, and appears very dejected. In this stage the animal may still be saved by the administration of carotene or vitamin A as supplied in readily available form such as cod i or other fish liver oil, Figure 5-. Figure 4. —more difficult to Steer just before falling to the ground with a, convul- sion. Upper—-Steer 63, Experiment 2, March 9, 1936, alert but at this time was completely night blind. Lower—the Same steer on April 10.‘ Note lack of ngrmal alertness, typical of vitamin A deficiency and following night blindness one of the early symptoms ususally observed. If this is not given the animal will soon die. ‘At autopsy one finds grossly the condition of the eye already visible during life. The hide is remove than normally, mostly due to the fact that the subcutaneous tissue, at the places where it is not edema- tous, is dry and tough. At the points of visible swellings the subcutaneous tissues show ede- matous infiltration which may be very extensive. Infiltration located more deeply may also be found at points where no swelling was vis- VITAMIN A STUDY IN FATTENING FEEDER CALVES AND‘ YEARLINGS 13’ ible externally and thus occur in the connective tissue between the muscles of almost any part of the body and the musculature is much moister than normally so that fluid may drip from a freshly made cut. In the intestinal tract a marked congestion o1‘: the mucosa may be found. An in- creased amount of fluid may also be found in the pericardial sac and in the subdural space. The spleen may be smaller than nor- mal and rather dry. In case of day blindness a degeneration of the optic nerve may be far enough advanced to be recognized grossly. Effect of Long Continued Feeding on Low Carotene Level The effect of the long con- tinued feeding of a carotene level insufficient to maintain life on feed consumption, gain and fat- tening was observed with 5 steers from Experiment 3, 1936-37, which were removed from Spur to College Station in May 1937. The ten 469-pound steer calves ori- ginally involved in this test Were started on depletion ration in No- vember 1936. They were the first 10 to become depleted out of the 5O head used in Experiment 3. Following their depletion, as in- dicated by night blindness, in March 1937 they were fed 450 micrograms of carotene supplied by dehydrated alfalfa leaf meal Figure 6 A steer affected by vitamin A deficiency may suffer from solar heat more th.an normal animals, Note r protruding tongue and marked nasal discharge and slobbering. This steer was restored 110 normal condition by dosage with cod liver oil. ' per 100 pounds live weight daily. They were fed the 450 microgram level until they either died or were sacrificed in extremis. these steers is summarized in Table 3. The performance of Two of the steers lived approximately 5 months, two more than one year, and one more than 2%‘ years on the 450 microgram level. In con- nection with the report of Keener and associates (15) that an increased amount of carotene seems to be required in severe winter weather it is '14 BULLETIN NO. 630, TEXAS AGRICULTURAL EXPERIMENT STATION noted that 4 of the 5 steers in this group died during the warm months and the other died prior to the advent of cold Weather. The steer-g consumed more than three pounds of the basal feed mixture per 100 pounds live weight daily prior to their trans- fer to College Station and con- tinued to consume good amounts during the next four or five weeks after their transfer. The defi- ciency then became more evident and all showed marked loss of appetite. Numbers 84 and 97 died at about this time but the others improved in appetite and seemed to get along quite well for 6 to 7 months when they again- became seriously affected, lost appetite and weight and Numbers 80 and 96 died. At this time it was dif- ficult to tell which of the steers was most seriously affected but Number 99 rallied and lived about 18' months longer. The rate of gain continued up- ward, but at slow rate after de- pletion, except for the periods when there was loss of appetite. Much. of the loss of Weight shown for such periods was caused by lack of fill. All of the steers be- came quite fat, Figure 8, showing that the ability of the animal to store fat was not impaired by the carotene deficiency in the ration except as appetite was impaired. Steer 99 became fat, as shown in Figure 9 (upper), but later lost flesh as shown at the end of 730 days; however he again regained fair condition before he died after 993 days on the 450 microgram level. Upper--Steer 44, Experiment, 2, 1935-36. This steer sal- though not day blind, had roughened dry hair 00am was still’ and sluggish, had scant appetite and showed marked edema in the shoul- der region. He had Sub- sisted upon a ration 10w in carotene for 381 days, was in an advanced stage of de- pletion, and his carcass was condemned. I-ower—Steer 96, Experiment 3, 1936-37, after 471 days on 450 micro- _ gram carotene level. This steer was down and unable to rise the following day and was sacrificed. Note swellings of legs. These steers showed the typical symptoms of vitamin A deficiency as previously described. It was quite evident from this work and from other work at Spur from 1934 to 1937 VITAMIN A STUDY IN FATTENING FEEDER CALVES AND YEARLINGS 15 Table 3. Performance of steers on 450 microgram carotene level, Experiment 3 i . l Gain in Date started Days Days re- Days 0n experiment, ibs. Steer 1 on depletion in quired for I carotene l\o. j ration Died experiment depletion ‘ level Total Daily | . s4 Nov. 23, 1936 July 27,1987 2146- 191 115 _ 421 1.71 97 NOV‘. 1936 Aug. 12, 1937 262 1018 154 3226 1.24 96 j NOV. 23, 1936 June 26, 1938* 580' 108 472 498 .86 so i Nov. 2s, 1936 July 9, 193s" i 600 115 485- 51s e11 99 i Nov. as, 19st Nov. 29, 1939+]! 1102 10s 99s 746 .68 *Sacrifice-d in extremis. . _ _ _ iSacrificed because of urethral occlusion caused by urinary calculi. that less carotene is required for feedlot gain than for the maintenance ' of health. In Experiments 1 and 3 steers levels. The treatments given to Effect of Various Treatments Curative treatments consisted in increasing the quantity of vitamin A potency in the ration through the use of green growing feeds, alfalfa hay or alfalfa leaf meal high in ' carotene; or through the use of cod or other fish liver oils, high in Vitamin A. affected byyitamin A deficiency were given various curative treat- ments. In the first instance the treatments were designed to iden- tify the condition which had re- sulted from feeding weaned steer calves a mixture of cottonseed meal, ground threshed white grain sorghum grain, and cotton- seed hulls, which condition had not resulted in similar groups of calves fed the same basal mixture but fed in addition 1, 21/21 and 5 pounds of alfalfa hay per head daily. In the second instance the treatments were employed to in- sure the marketability of fattened steers since rather severe defici- ency had been allowed to develop in them in testing low carotene Figure 8- 51861‘ N0 80 lived for 435 ' days on the 450 mi¢r0€r§lm level including the depletlfln . - period. The pictures show the 10 steers, Lot 1, Experiment him after 320 days of feed: 1, 1934-35, are shown 1n Table 4. ing on this level. The high finish and abnormal p head carriage are evident. Cod liver oil given as a drench 16 BULLETIN NO. 6-30, "TEXAS AGRICULTURAL EXPERIMENT STATION in 25cc and 50cc doses daily to 3 steers suffering from vitamin A deficiency effected definite im- provement in condition in 15 days and there was some improvement in 7 days. One steer given 10cc of cod liver oil daily‘ improved in general condition in 15 days but remained night blind. The cod liver oil used in these treatments was registered for a potency of 500 units of vitamin A per gram, but upon assay showed 550 Sherman-Munsell rat units. Upon the latter basis the two steers whichi were fed 50cc of cod liver oil received 3400 units of vitamin A per 100 pounds live weight daily; the one fed 25cc, 1575 units; and the one fed 10cc, 620 units. One steer was given 10cc and another 25cc daily of pure crystal- line carotene (having 5000 Inter- national Units per gram) dis- Figure 9. Steer No. 99 lived for 993 days on the 450 microgram solved in maize oil. Both steers carotene level and 1102 days . . . . . including the depletion pe- improved in condition as quickly 140i The pictures Show as the steers given cod liver oil. him after 32° and 73° days _ (upper and lower respec- The one given 25cc of carotene tiveiy) of feeding‘ on this daily was treated for only 14 days level‘ and madespectacular recovery, but was again droopy and sluggish 30 days after the treatment was discontinued. The steer given 10cc daily for 40 days while showing improvement did not completely recover from labored breathing. A Aerated cod liver oil, that. is cod liver oil in which the vitamin A had been destroyed by heat and oxidation, fed in doses of 25cc and 50cc daily completely failed to correct the condition which had been found. One- half pound and one pound of alfalfa hay and one-half pound of fresh green alfalfa fed to the steers which did not improve on the aerated cod liver oil effected some improvement in condition. The steer fed one-half pound of green alfalfa improved rapidly in both night vision and general condition, but those fed the alfalfa hay made slow and only partial improvement. In fact, the steer fed one-half pound of alfalfa hay made such little improvement that it was changed to 4 pounds of fresh green sudan grass daily. Improvement occurred within 10 days after the change to sudan grass. One steer which was continued on the basal carotene deficient mixture a.nd which was not given a vitamin A or carotene supplement died on the Table 4. Treatment of vitamin A deficient steers, Experiment 1, 1934-35, on basal ration of cottonseed meal, cottonseed 1111118, and white grain sorghum grain ' Before affected Wt. loss Daily Treatment prior to Steer Days on Daily Date improve- Date I Date Days to N0. ration gain, lbs. affected ment, lbs. started 1 stopped improve Remarks on July 22 1 35 116 2.01 April 1 26 May 6 50cc cod live-r oil ________________ -_ July 17 15 Normal 19 124 1.87 April 8 27 Ma-y e 50cc cod liver oil-ma __________ -_ July 17 15 Normal 39 124 1.78 April 8 61 May 6 25cc cod liver oil _________________ _- July 17 15 Partial recovery 22 125 2.08 April 9 52' May 8 50cc aerated cod liver oil* ______ -- June 7 __ Did not improve __ ___ ______ __ __ June 7 1/2 1b. fresh green alfalfa _______ __ July 2'2 38 Partial recovery 37 1.36 2.12‘ April 20' 26 May 14 50cc aerated cod liver oil* ______ -- June 7 __ Did not improve __ ___ ______ __ __ June 7 1 lb. alfalfa hay ________________ __ July 17 36 Partial recovery 8 154 2.28 May 8 55 May 15 25cc aerated cod liver oil* _______ __ June 7 __ Did not improve -_ ___ ______ __ __ June 7 1/2 lb. alfalfa hay __________ __.-__-_ July 12 3-3‘ Partial recovery -_ ___ ______ __ -_ July 12 4 lbs. fresh green sudan ________ __ July 22 10 Marked improvement 26 154 2.27 May 8 42 June 13 10cc cod liver oil__-. _____________ -_ July 17 318 Partial recovery 15 154 2.281 May 8 20 June- 7 10cc carotene in maize oil _______ -- July 17 8 Partial recovery 6 167 2.43 May 21 7 June 7 25cc. carotene in maize oil _______ __ June 2'1 10 Made marke-d improvement but again droopy 29 140 2.10 April 2'4 6:6 ______ __ No treatment- __________________________ __ __ Died after 179 days *(3od liver oil in which the vitamin A had been destroyed. LI SEMTITHVEIL CINV SELNIVC) HEIGHELEI SNINELLLVLE NI ACULLS V NIWVALIA 18 BULLETIN NO. 630, TEXAS AGRIQULTURAL EXPERIMENT STATION 179th day of the experiment. This fact, together with the failure of af- fected steers t0 improve when ‘fed the aerated cod liver oil, the improve- ment and recovery of affected steers when fed cod liver oil, pure crystal- line carotene and feeds containing carotene and the absence of affected condition in the steers which had been fed alfalfa hay in addition to the basal mixture from the outset showed that the lack of vitamin A was the sole cause of the condition encountered in the steers fed the basal mixture of cottonseed meal, ground threshed grain sorghum grain, and cottonseed hulls. _In Experiment 3, 1936-37, various dosages of cod liver oil were given A to 17 steers which showed marked symptoms of vitamin A deficiency fol- lowing the supply of low levels of carotene. Dosages of 1000 to 2000 USP units of vitamin A (based upon the guarantee of the processor of the cod liver oil) daily per 100 pounds body weight were employed dur- ing a period of 29 to 43 days. Unit dosages were given daily, and at in- tervals of 1, 7, 15 and 30 days. The dosage given at an interval of, for example 7 days, was 7 times ' greater than the daily dosage or 7000 units of vitamin A per 100 pounds body weight. There was a wide difference in degree of af- fected condition among the steers at the start but there was some uniformity in response to treat- ment. I e Four of 7 steers which had been supplied carotene levels of 450 to 600 micrograms following de- pletion improved in night vision upon dosages of 1000 to 1500 units of vitamin A daily per 100 pounds body weight. Dosages of 2 0 0 0- units effected slightly greater improvement. Although the dosages of cod liver oil did not completely restore night vision in the periods of treatment in- volved, marked improvement in ' ' ' _ Figure 10. Steer 56, Experiment 3 appetite and general condition fol showing typical change m’ lowed. After a few days of treat- general health following - restorative treatment. ‘Up- ment steers which had been slug- per__0n 5/21 before start gish and off feed became alert 0f treatment was siok, 11511- . . . less, and suffered from solar and anxious for their feed. Dos- heat Lower_A1-, market ages given daily or at intervals g/EQ- gfgesgegafiIigy agllgfliglfigg of one day appeared to be equally steer although st111 night - - blind and showing some effective. The same unit dosages degree of ineeerdmet1en_ VITAMIN A STUDY IN FATTENING FEEDER CALVES AND YEARLINGS 19 given at longer intervals effected marked improvement in a few days, but the beneficial effect.usually failed to last until the next treatment. Following the treatments with cod liver oil part of the steers were kept for an additional 28 days and were fed either fresh green alfalfa or alfalfa hay free choice. An improvement in night vision resulted in all ex-E cept one steer of the 12 involved in this final period of treatment. The be- . havior of this steer which showed complete night blindness as well as that of others which were slow to improve indicates that vitamin A de- ficiency may result in injury to tissues which are not readily healed even when large amounts of carotene or vitamin A are supplied. A persistent fullness at the hooks among some of the steers retained for the final period of treatment was of concern to the observers. There was no gen- eral improvement in this condition, as judged by the eye, from the treatments; however, all of the steers afforded acceptable carcasses under B.A.I. inspection. Figure 10 shows a case of improved well-being fol- lowing restorative treatment. TIME REQUIRED FOR DEPLETION OF BODY RESERVES OF VITAMIN A IN FEEDER CATTLE IN DRY LOT There was wide variation in the time required for depletion of vitamin A reserves as indicated by the onset of night blindness between indi- viduals, between feeder groups of different age, and between years with feeder groups of the same approximate age and initial weight. This problem has been discussed in some detail by Riggs (8) whose report covered the present work up to 1939-40. The variation in time re- quired for the depletion of 310 feeder cattle used in this phase of the study is shown in Table 5. - Wide variation was particularly apparent among the yearling steers used in 1935-36 in which the range was-128 to 266 days, average 178 days, and a standard deviation of 37. In contrast the widest variation found in well grown feeder steer calves‘ of approximately 450 pounds initial weight, was 101 to 206 days with a standard deviation of 25. The least variation in the well grown steer calves was from 82 to 155 days for 1938-39; but 10 younger steer calves, with an average initial weight 289 pounds obtained at the same time became depleted in a range of 83 to 90 days. The wide differences in time required for depletion of individuals in the same year indicate thatvdifferent individuals have different reserves of vitamin A in the body and suggest possible dif- ferences between individuals in ability to utilize carotene for a given function. The smaller degree of variability as well as the shorter time required for depletion of the younger animals tends to indicate a smaller storage for them than for the older animals. The variation in time required for depletion of the feeder calves used from year to year definitely indicates a relationship between rainfall, the vitamin A potency of the range forage and the body storage of vita- min A reserves. Table 6 shows the monthly and annual rainfall at the Spur Station during the course of these experiments. Table 5. Time required for depletion of vitamin A reserves in 310 feeder cattle. Year 1935-36 1936-37 1937-38 1938-39 1938-39 1939 1939-40 1%9-40' 1940-41 Total Class Steer Steer Steer Steer Steer Steer Heifer Steer. Steer yearlings calves calves calves calves calves calves calves calves Number 48 40 501 50 10 12 30 20 50 310v Age in months 16 6-8 6-8 6-8 4-6 3-5 4-6 3-5 4-6 ___ Initial Weight, lbs. 559 469 448 464 2f89' 246 330 225 26-8 -.._ Days for depletion 45- 59 ___________________ __ __ -- _- __ __ 6 __ __ __ 6 60- 74 ___________________ -_ -_ __ __ -- __ 6 -- 11 11 2'8 75- 89' ___________________ __ __ __ _- 10 10 __ 1 6 -_ 27 90-101 ___________________ _ _ _ _ 9‘ 1 20' _ _ _ _ 25 2 25 8-2 109-128 ____________________ __ 5 1 16 15 __ __ 4 1 12 54 1291-148 ___________________ __ 9 18 19 3 __ __ __ __ 2 51 149-168 ___________________ _- 10 8 13 2 __ __ __ __ __ 33 169-188 ___________________ __ 5 2 __ __ __ __ __ __ .... 7 18-9-208 ___________________ __ 5 2 1 __ __ __ __ __ __ 8 ' 209-228 ___________________ __ 13 __ __ __ __ __ __ __ __ 13,- 229-248 ___________________ __ __ __ __ __ __ __ __ __ __ __ 249-268 ___________________ __ 1 __ __ __ __ __ __ __ __ 1 Range ------------------------ __ 128-266 101-206 96-194 82-155 83-90 46-61 82-112 65-131 72-134 Avfirage- _____________________ __ 178 136 138 107 86 56 98 79 98 Standard deviation _________ __ i37 +25 i21 i211 i5 i6 i7 i17 ils NOLLVLS CLNIHWTHEIJXEI TVHILLTIIOTHSV SVXELL ‘O89 ‘ONI NLLEYITIISI VITAMIN A STUDY IN FATTENING FEEDER CALVES AND YEARLINGS 21 Table 6. Jlonthly and. annual railfall in inches at Spur Station, 1934-40, Average Month 1934 1936 1966 1987 1988 1969 1940 by months i January_ ______________ __1 .12 .01 1.11 ,3s 1,14 19g _1@, 370 February- ------------- -- .21 .61 Trace Trace 6.31 .25 1.14 .79 lllarch ------------------ -- 2 20 .99 .22 2.05 .82: .52 __ .83 April ------------------- __ 1 16 .71 2.49 .86 .89 .29 1.79 1.17 May ____________________ __ 2 50 4.54 2.79 2.921 2.89 2,07 1.17 2,70 J1me ------------------- -- 6T 6.96 1.49 1.31 5.16 1.80 1.06 2.54 July -------------------- -- .11 .99 21.86 .68 6.80 .44 07 1.21 August _________________ __ 1.18 1.05 .11 6.93 .21 1.85. 3 24 20s S-eptemben ____________ __ 2.5.2 3.62 11,13 2,18 p9 __ 4.1 285 Qctober ---------------- .87 2.22 1.41 2.47 1.36 2.62 1.34 1.75 hovembcr ______________ -_! 1.93 1.50 .48 09 .78 .60 s 16 1.22 December ______________ _- .01 .62 .45 41 .04 .64 04 .32 Total- _________________ _- 12.88 22.78 _ 2.4.47 E2028. 19.96 13.06 13.68 18.29 July-October total ____ -1’ 4.68 7.88 16.50 12.26 4.99 4.91 5.06 7.89 l The average time required for depletion of 450 pound feeder steer calves purchased in the fall of 1936 and the fall of 1937 was 136 and 138 days respectively. During each of these two years the July-October rainfall was relatively high. In 1938, however. when the July-October rainfall totalled only 5 inches as compared to 15 and 12 inches in the two previous years the average time for depletion. of steer calves of the same approximate age and weight was only 107 days. Heifer calves, initial weight 330 pounds, and steer calves, initial Weight 225 pounds, taken from the range in the fall of 1939; and 289 and 268 pound steer calves taken from the range in the fall of 1938 and 1940 respectively required in order of mention averages of 98, 79, 86, and 98 days for depletion. The July-October rainfall averaged approximately 5 inches for those years. Ten of the heifer calves taken from the range in the fall of 1939 and fed 1000 micrograms of carotene per 100 pounds live weight daily from the outset required an average of 113 days or 15 days longer to become depleted than the group of 30 fed the deple- tion ration from the outset. In a supplementary test of the time required for depletion, 12 steer calves having an average weight of 246 pounds were removed from relatively dry winter range before the spring growth of grass began and placed on a depletion ration in March 1939. Sumac fodder which had been stored two years supplied the bulk in the ration in place of cotton- seed hulls. All of these calves became night blind in 61 days, the aver- age being 56 days and the range 46 to 61 days. Other workers have reported similar findings. Connell and Carson (1) failed to produce “fat sickness” in aged steers by feeding cottonseed meal and cottonseed hulls in a period of 180 days. Guilbert and Hart (16) reported complete night blindness in two yearling steers fed a carotene-deficient ration in approximately 250 days after their removal from conditions which afforded excellent storage of vitamin A reserves. 22 i BULLETIN NO. 630, TEXAS AGRICULTURAL EXPERIMENT STATION Mead and Reagan (17) reported the development of vitamin A defici- ency in calves 1 to 3 months after the diet was changed from whole milk and grain to a concentrate mixture low in vitamin A potency. Moore (18) found that 2 calves raised to 90 days of age on whole milk and grain and then fed skim milk and low carotene grain ration became night blind, one in 38 days and the other in 63 days. Black, and associates (19) did not note any disorders among 310-pound feeder steer calves fed ground milo heads, cottonseed meal and cottonseed hulls in a 203- day fattening period. However, tests were not conducted for night blindness. Schmidt (9) has reported differences in the time required for the depletion of vitamin A reserves in ruminants. He observed that pasturage at College Station, Texas was deficient in carotene after the first killing frost and that yearling goats placed on a deficient ration at the first killing frost survived as long as those kept on ordinary winter pasturage without access to green feed of any kind for 30 days longer before being placed on the same depleting ration. The findings in regard to the time required for depletion of body re- serves of vitamin A show that older feeder cattle possess greater re- serves of vitamin A than younger ones a11d that the condition of the range from which the feeders were removed may be expected to affect the body reserves and the consequent time required for depletion. In dry years with limited amounts of green vegetation the time required for depletion was less than in years of more abundant rainfall and consequent greater amount of green vegetation. It was evident that the onset of vitamin A deficiency may be hastened by the degree of carotene shortage in the ra- tions fed in dry lot. It was also evident that feeders may go for consid- erable periods in the dry lot without suffering from vitamin A deficiency to an appreciable extent; however, such periods are not usually long enough for fattening feeder calves on carotene deficient rations. Calves may require more than 200 days for fattening and in these tests most of the feeder calves used became depleted before 120 days. EFFECT OF QUANTITY OF CAROTENE UPON NIGHT BLINDNESS , AND RELATED SYIWPTOMS OF VITAMIN A DEFICIENCY The experimental animals used in this phase of the study were fed a ration low in carotene until they were depleted of body reserves of vitamin A, as indicated by the occurrence of night blindness. In Experiment 2, 1935-36, as the yearling steers used became depleted they were started on a designated carotene level and fattening grain ration individually fed. The measure of depletion was at least two ob- servations of complete night blindness for Groups 1, 2 and 3, but slightly less evidence of depletion was required for Groups 4 and 5. The first 10 steers to become depleted formed Group 1; the second 10, Group 2, and so on with the last 8 forming Group 5. Groups 1, 2, 3 and 4 were supplied in respective order approximately 200, 350, 500, and 750 micro- grams of carotene from alfalfa per 100 pounds live weight daily. Group 5 was placed on a level of approximately 2400 micrograms of carotene VITAMIN A STUDY IN FATTENING FEEDER CALVES AND YEARLINGS 23 since the groups started on the low levelshad already shown advanced symptoms of vitamin A deficiency. The carotene levels, including the carotene supplied by both alfalfa and grain, and the period of time in which they were fed are shown in Table 7. Table 7. Summary of Experiment 2, 1935-36. l l Depletion period l Treatment, period *Gain for experi- GIjOlID l _ mental period, l\o. l Gain, lbs. Carotene-l l Gain, lbs. pounds l DHYS l——— ——_—~— level, No. l . , l Total l Dally mcg. days l Total Daily Total l Daily l l l l l l l . . l l 1 l 154 l 200 l 1.61 282 20 l 24 l .s4 l l l 1751 169' l 238 l 1. 41 462‘ l 1.43 l l l ll 2 181 l 234 l ass 2.1 24 l 1.16 l l l 1033 150' l 1S4 1 . 213 442 l 1 . 37 3A l 205 l 250 1 1 . 4-3 549 148 151 1 .012 401 1 . 25 3B 20-2 25s l 1.50 42s l 41 A -15 - .36 l l l 1301 l 112 l 143 1 .28 3S6 1 .20 1 l 22s 28s l ' 1.47 s00 l 142 160 1.27 44s 1.39 1 l ‘ l 5 246 1 309 l 1 . 43 l 2364 l 1017 l 150 1.40 459' 1 .43 “These data pertain only to that period when all of the animals were on experiment, a period of 3Z2 days. With the first groups becoming depleted in March and April the lower carotene levels were assigned to them with the idea of completing the test of these levels before the advent‘ of hot weather, for it had been noted in the first experiment that the heat of summer intensified symp- toms of vitamin A deficiency. As expected, the three lower levels proved to be inadequate for the maintenance of health and Group 1 was raised to approximately 1800 micrograms of carotene in alfalfa, Group 2 to 1000 micrograms, and the 5 most seriously affected steers in Group 3 to ap- proximately 1300 micrograms as shown by Table 7. - Group 1 "steers remained on the low carotene level an average of 30 days before their carotene level was raised to approximately 1800 micro- grams in alfalfa. After the increase an average of 16 days elapsed be- fore improvement in physical condition was noted. Seven of the 10 steers regained a marked degree of night vision after 107 days, but the other 3 became day blind 48 days after the increase in carotene level. Group 2 steers were on a low, 386 microgram, carotene level an average of 21 days after depletion before being raised to approximately 1000 micrograms in alfalfa. They improved in physical condition and as a group regained a degree of night vision- One steer became day blind and 2 others became day blind in one eye. Six were observed in convulsions a total of 12 times with one being observed for 5 such seizures. 24 BULLETIN NO. 630, TEXAS AGRICULTURAL EXPERIMENT STATION Group 3 steers were started on a carotene level of approximately 500 micrograms and after 41 days the 5 showing the most advanced symptoms of vitamin A deficiency were raised to approximately 1300 micrograms. Four of the steers which remained on the 500 microgram level for an average of 148 days became day blind, the other remained night blind and all showed advanced vitamin A deficiency but only two were ob- served for convulsions. Three of these steers which were kept for an additional month and were not marketed until November 2, 1936 were observed to suffer markedly from brief periods of cold. Suffering from cold by animals on low levels of carotene has been confirmed by Keener and associates (15). Also, 2 out of the 5 carcasses were rejected be- cause of a generalized edema, which condition has also been reported by Creech and Madsen (20). Of the 5 steers from Group 3 which were raised to 1300 micrograms for a period of 112 days partial improvement in night vision was certain for two, while two became day blind and the other became day blind in one eye and remained night blind in the other. A total of 15 convul- sions were observed in these steers, all animals being affected, but otherwise they were not as severely affected as the ones continued on the 500 microgram level. Group 4 steers were considered as depleted upon ‘the basis of slightly less evidence of complete night blindness than was required for Groups 1, 2 and 3. These steers showed improvement in night vision in the 142-day test period and improved in physical condition. Three out of 5 of this group held for an additional month on the 800 microgram level showed decline in both night vision and physical condition toward the close. One convulsion was observed for this group. Group 5 steers were started on the 2400 microgram level when only partially night blind as compared to practically complete night blindness for the other groups. These steers did not show much evidence of night blindness until after 216 days on the depletion ration and showed other symptoms of vitamin A deficiency to only slight degree. They regained normal night vision within 4 to 6 weeks after the start of the 2400 micro- gram level and were lively and alert at the close as compared to all other groups. All steers fattened to a comparatively high degree except those on the 500 microgram level which were severely affected by vitamin A defici- ency to the extent of going off feed. Dosages 0f cod liver oil supplying about 25000 USP units of vitamin A per head daily given to steers kept for a final month of feeding effected marked improvement in physical condition and in night vision in all instances, but did not have effect upon the vision of the day blind steers. VITAMIN A STUDY IN FATTENING FEEDER CALVES AND YEARLINGS 25 The procedure and results of Experiment 2 have been given in detail because of the extreme variation found between-individuals, because a large number were severely depleted and because the results were som.e— what different in regard t0 night blindness from those found from the use of calves in succeeding experiments. The procedures used in later experiments, particularly that of requiring only definite assurance of af- fected night vision, also the procedure of equalizing the degree of de- pletion prior to the start of test of carotene levels were based on the results of Experiment 2. The average gains for the groups are shown in Table 7, but are not discussed because of differences in group treat- ments. In Experiment 3, 1935-36, Group 5, 10 steers were started on 800 micrograms of carotene per 100 pounds live Weight daily at the outset. The remaining 40 steers were fed the depletion ration and the first 10 to become depleted formed Group 1 while Groups 2, 3, and 4 were formed as the steers successively reached depletion by alternate place- ment. The last four groups to be formed in respective numerical order were started on levels of 450, 600, 750 and 1000 micrograms of carotene. All groups became and remained night blind on these levels and a wide range of other symptoms of vitamin A deficiency developed and reached such degree of intensity that various treatments were employed. Except for a general condition of fullness or swelling at the hocks appearing in all groups, the symptoms of vitamin A deficiency observed in this experiment were not essentially different from those found in Experiment 2. However, the symptoms were less intense since the animals were not allowed to reach such advanced stage of deficiency before the carotene levels were raised or other treatments were employed. In Group 1 complete night blindness developed soon after the start of the 450 microgram carotene level and remained until other treat- ments were used. Groups 2, 3, and 4 likewise, and in succession, be- came more night blind but required more time and had lower average degree of night blindness and were less seriously affected by vitamin A deficiency than Group 1. Group 5 steers required 61 days longer to be- come depleted as indicated by night blindness than the average for the other four groups and when their carotene level was raised from 800 to 2000 micrograms quickly regained normal night vision. Groups 2, 3, and 4 regained normal night vision following the supply of alfalfa hay free choice, but Group 1 which had been more seriously depleted than the others did not entirely regain normal night vision before the close. The cod liver oil treatments which were used have been described under the discussion of curative treatments for vitamin A deficiency. There was improvement in night blindness following the treatments with cod liver oil, however, these treatments were not continued very long and rather small amounts were allowed. Experiments‘ 4, 5, 6 and 7 involved the study of higher levels of caro- tene than Experiments 2 and 3. Feeder calves were used and the test periods were for 140 days after depletion; except for Experiment 6, with 26 BULLETIN NO. 630, TEXAS AGRICULTURAL EXPERIMENT STATION a test period of‘ 100 days. The observations for degree of night blind— ness and convulsions resulting from the several carotene levels used in the four experiments are summarized in Table 8. Table Li. Degrees of night blindness shown for various carotene levels fed after depletion. Number of animals and degrees of night blindness Carotene l Con Experi- Level Degrees at beginning l Degrees at end l vul- ment Mcg. l---- l signs I 1° l 2i“ a“ l 1° ’ 2° l s" l l l l l 4 s00 l 2 l a 2 l 0 0 7 0 1000 3 3 l 4 0 0 3 4 0 1937-38 1250' 2 . l 4 1 0 1 6 0 140 (lays 1.500 ~. 4 l 2 1 .- 4 2 0 2000 l 2 l 4 1 l 0 1 0 5 800 1 l 3 4 O 0 8 23 1000 l 1 l 5 2 , If 0 s 1938-39 1250 f 2 3 4 2 0 1 7 1 J40 days 1500 l 1 l 4 3 0 1 7 1 2500 0 l 5 s 0 e 2 0 l 6 800 5 l 2 3 0 0 10 3 1000 1 l 4 5 0 o 10 2 1939-40 1500 1 l 2 T 0 1 9 stagger" 100 days 1000' 3 2 4 O O 9 2 7 12.50 s l z 0 0 1 7 2 1500 a l . a 0 0 s a 1 1940-41 2500 l 6 l 2 0 3 4 1 0 140 days 3000' l 4 l 4 1 0 3 3 1 0 5000 l 4 l 4 O 3 0 0 0 l *No convulsions. observed among cattle fed at the 1500 meg. level; however, 2 heifers showed staggering gait which were probably closely associated with convulsions. In these four experiments in which 115 feeder calves were fed caro- tene levels ranging from about 800 to 1800 micrograms per 100 pounds live weight daily, 99 were completely night blind, 15 showed 2 degrees of night blindness, and one showed 1 degree at the close of the test periods. Of 23 head fed levels of 2000 to 2500 micrograms, 4 were com- pletely night blind, 16 showed 2‘ degrees, and 3 showed 1 degree. Of 8 steers fed 3000 micrograms, one was completely night blind, 3 showed 2 degrees, 3 showed 1 degree and one was normal. Of 8 steers fed 5000 micrograms, 5 were normal and 3 showed 1 degree of night blindness. Convulsions as observed were recorded, Table 8, perhaps because of their alarming nature rather than because of their being a common manifestation of vitamin A deficiency. It is also to be understood that the animals were not under continuous observation so that convulsions could have occurred that were not observed. No convulsions were ob- served in Experiment 4, but in Experiment 5, 1938-39, the number of convulsions was correlated with the carotene level in that 23 convulsions were noted for 6 steers in Group 1 on 800 micrograms, 5 for 5 steers in Group 2 on’ 1000 micrograms, 1 each for Groups 3 and 4 fed 1250 and 1500 micrograms and none for Group 5 fed 2000 micrograms. In Ex- VITAMIN A STUDY IN FATTENING FEEDER. OALVES AND‘ YEARLINGS l 27' periment 6, 1939-40, in which 3 groups of heifer calves were supplied approximate carotene levels of 800, 1000, and 1500 micrograms for 100 days following depletion, and the fourth group was fed 1000 micrograms from the outset 3 convulsions were observed on the 800 microgram level and 2 were observed for each of the groups fed 1000 micrograms. No convulsions were observed on the 1500 microgram level.but 2 of the heifers were observed for staggering gait and this condition according to observation is closely associated with convulsions. In Experiment 7, 1940-41, 2 convulsions were observed for Group 1 on 1250 micrograms and 1 for Group 2 on 1500 micrograms. One other steer in Group 2 showed staggering gait at the close of the 140-day test period. On levels of 800, 1000 and 1250 micrograms of carotene clinical symp- toms of vitamin A deficiency were much more evident than upon the higher levels; however, there were differences in the symptoms and in their intensity between years for the same levels. In Experiments 4 and 5 the steers fed the 800 and 1000 microgram levels were more difficult to keep on feed than those fed the three higher levels. Fullness at the hocks was observed sooner or later among almost 100 per cent of the steers on all of the levels. As compared to cattle which had received an abundance of carotene all groups showed more suffering from summer heat and more of the condition of watering‘ at the eyes. In Experiment 6, despite the low levels of carotene used the groups of heifers were prac- tically normal in appearance although a few individuals showed affected condition. These heifers, however, were kept on the test level for only 100 days and were marketed June 1 or before hot weather set in. In Ex- periments 6 and 7 the fullness at the hocks as noted in Experiments 4 and 5 did not occur. The steers used in Experiment 7 also showed few outward manifestations of vitamin A deficiency, except as previously noted for the 1250 and 1500 microgram. levels. All of the cattle used in these four experiments fatt-ened to a satisfactory finish and were sold for slaughter without rejection. However, on the basis of the observed symptoms of vitamin A deficiency, even 1500 micrograms of carotene per 100 pounds live weight daily did not maintain an entirely desirable degree of health. Of 33 animals involved in the study of this level, two were observed to show convulsions and 3 others were observed to show staggering gait and there was other evidence of continued depletion on this level in the 140-day period of feeding. The trend of depletion as evidenced by night blindness for the several carotene levels used in Experiments 4, 5, 6 and 7 is shown in Figures 11, 12, 13 and 14. The curves representing the degrees of night blind- ness observed for the several carotene levels show that 1500 micrograms of carotene per 100 pounds live weight daily or less are inadequate to control night blindness, that various degrees of night blindness persist in the range from 1500 to 2500 micrograms and that levels of 2500 to 5000 micrograms may control night blindness quite Well in the periods. of time in which the levels were supplied. 28 BULLETIN NO. 630, TEXAS AGRICULTURAL EXPERIMENT STATION 3-0 .2 .// /><" ’ Z \\ f’ Z \\ ,1 245 \‘ [I/ \ \ v \\ \ 4 5 \ ,./" .5 2.0 \ .5 ___...4.___ g x2 + +\ a ‘ I s / / _ s: >‘ \ u 1.5 o Q Q Q :- m o a 1.0 Legend: 0'5 /' BOO ug per wt. _ ,/ 1000 ug per :w't. ____ 1' 1250 u; per wt. ____--- I,’ N _ 1500 u; per m. .______ / +/ " 2000 g per pvrt. __4 _., 0.0 1 , _ l l5 l 15 l. 15 L 1E 1 15 1 l: 1 15 Feb J March Apri 1. May June Ju 1y Aug. Figure 11. Experiment 4, 1937-38. Response of night blindness of steers to caro- tene level. The animals were depleted and started on their carotene levels on April 1. The curves represent the average for all animals fed a. given level. ugzmicrogram. The separate figures and individual curves representing the different groups show other interesting phenomena. It was noted in Experiment 3, and in’ Experiment 2 that there Was a definite improvement in night blindness when low carotene levels were succeeded by higher carotene levels. Except in the case of severely depleted animals the effect is al- most immediate improvement in degree of night blindness as noted in Ex- periments 4 and 5, Figures 11 and 12. There was a decrease in night blindness on each of the carotene levels for the first two Weeks im- mediately after the carotene feeding began on April 1st in Experiment 4, and similar improvement resulted from the three higher levels used in Experiment 5. These decreases in degree of night blindness would have been misleading had the experiments been closed at the time, for there was an increase in night blindness upon all levels with the con- tinuation of the experiments. Figure 14, Experiment 7, 1940-41, shows that on March 6th tankage was removed from the ration of the steers fed the 1500 microgram caro- tene level. This was done in an effort to determine whether the tank- age used was exerting a destructive action upon the carotene supplied by the dehydrated alfalfa leaf meal. No improvement in night blindness oc- curred after the tankage was removed from the ration. VITAMIN A STUDY IN FATTENING FEEDER CALVES AND YEARLINGS 29 3-0 l _-__- Z -—- / :—_ k ’ f I ‘QQ- Z ,!’ ~/ l -{ ; I 2 5 /, ~A'\ ‘I fill t 1/ x\ Q 3 /\ / 11/ +---+---‘|--—-4- l * s o . \4 // \ r Li‘; 2. . ‘kxw?! l x\ i/ Q \‘_ g ‘l’ *\ ['5 r/ 2 / , ‘6 1.5 ,. .' k‘ r g / //’ \ / a 'l~ w . a \ / 1 0 l/ / ‘ I / ;II%-*7IX II /!’,,! \ Legend: 0.5 ,/ 7:,’ cvu ug PET °"“'___ // ,//,/ 1000 ug per cwt...____--- /,//’ 1250 ug per cwt-------- ,/§' _ 1500 mg per cWt-_---—— " 2500 ug per wt¢——+-— 0.0 1 15 1 15 1 1e 1 1 1 i221». l Mall-Sh l Apll-il May June ‘MY Figure 12. Experiment 5, 1938-39. Response of night blindness of steers to 11am- tene level. The animals were depleted and started on their carotene level on March 15. The curves represent the average for all animals fed a. given level. ug‘:microgram. Other workers report that they have controlled night ‘blindness with smaller amounts of carotene than was required in these Texas tests. Guilbert and Hart (10) in a study of the minimum carotene requirement by the curative method in which recovery experiments were started when the animals exhibited complete blindness in semidarkness and in which the intake of alfalfa supplement for each animal was repeatedly in- creased and decreased until night blindness and other symptoms disap- peared or reappeared reported that the minimum requirement for beef cattle ranges from 26 to 33 micrograms per kilogram which is equivalent to- 1182 to 1500 micrograms per 100 pounds live weight daily. In con- tinuing the study of minimum carotene requirements these California workers (21) reported that the minimum requirement for mammals is in the order of 20 to 3O micrograms of carotene per kilogram body weight. The minimum requirements as determined by these investigators were defined as the lowest level per unit of body weight that prevented any detectable degree of night blindness under standard light conditions. Ward, Bechdel, and Guerrant (22) reported that the minimum carotene requirement, an intake sufficient to maintain growth and to prevent the usual symptoms of vitamin A deficiency, of growing Holstein calves was 11 micrograms of carotene from a carotene concentrate per pound of body weight per day. It appeared that Guernsey calves required a slight- ly higher level. It also appeared that the intake should be considerably BULLETIN NO. 680, TEXAS AGRICULTURAL EXPERIMENT STATION 3'0 r "—""_ _—" "'7 - '-—---.-::" 5 r I, / If Q\\\ "'_\‘ 4r’ / I \f'::-__-_-\-.-—|//, ’ll// f \~ ,1 I ' ‘ 2.5 .1 I 1 ' / / I /\ / \ I . -/ 5:: / X‘ / 7 l? 2 o ' "I / r ' ‘I ' s /. / P‘ I an l, / 14’ l’ ' 1,5 In l "-1 I | I Z 1 l "a /.‘ I ., /' I a> I ' 3 1.0 I! / I I ‘s? ' / c» /.' , ; / Legend: l,’ , 800 ug per cwt. i; O 5 V" / lOOO ug; per out. --—— ' /"/,/ 1500 ug per cwt. ____- , y’ 1000 ug per cvrt. // from the start —--—- If’ ‘ 0.0 ’ l l5 l l5 1 l5 l 15 l l5 l Jan, Feb. March April May -I'igure 13. Experiment 6, 1939-40. Res ponse of night blindness of heifers to caro- tene level. '.I.'he animals were depleted and started on their carotene level on February 15. The curves represent the average for all animals fed. a, given level. ugzmicrogram. above 11 micrograms, although larger amounts did not result in any marked improvement in rate of growth. Larger amounts of carotene were also required when the carotene was supplied by such feeds as alfalfa or timothy hay and silage feeds. In a more recent report from the Pennslyvania Station by Keener, Bechdel, et al (15) it is stated that the minimum carotene requirement of dairy calves maintained at an environmental temperature of 50° to 70° F. was found to be approximately 12 micrograms per pound of body weight per day, but during severe winter weather calves receiving 20 to 23 micrograms of carotene per pound of body Weight per day were observed to show deficiency symptoms. The authors state that the minimum carotene requirement for growth and well-being of dairy calves appears to depend upon environmental temperature. There are points of similarity between the California and Pennsyl- vania results and our Experiment 2, involving yearling steers, in which some improvement in night vision resulted from the supply of a level of 1000 micrograms of carotene following the appearance of complete night blindness and the supply of an initial level of about 375 micrograms of carotene. Temporary decrease in night blindnesswas also noted in Ex- VITAMIN A STUDY IN FIUYIENING FEEDER CALVES AND‘ YEARLINGS 31 1 3.0 Legend _ . 1250 w; per cvrt. ‘i? ‘ 1500 u; per curt. __. -_.- 2500 u; per clrt. 4.-----‘ 3000 u; per cirt. ---_- \ - 2,5 Bflfifi u’ per n * * / /-ii-i- / : ___ I 2 '\\ Z _ v 2.0 ’ * . . 5 / / \ Z! 3"? mkage omitted rorn th s g / rltion beginning March g / w w! Z *5 1-5 ”,<_\‘ z ~\_ § /’ ‘~~. h» / g \ V ‘l’, 1.0 ‘\ " ' ' \\\\ ,1 \ “\\ 1' / \\ N _ \\_I' / / !l\ $_ /' A i‘ ' u \ ~‘ ,/——-— . , / ' \ ' \Z \ / 0-6 1v - \, /‘%\' \ i? ' l - if,’ + \*\ Z ,. ~+—+\ 1 l’; l‘ ~+ / 0'0 1 s 1 1s 1 1s 1 :15 1 1s 1 15 1 15 Nov. Dee. Jun. Feb. March April . May Figure l4. Experiment 7, 1940-41. Response of night blindness of steers to carotene, level. The animals were depleted and started on their carotene levels on January 1. '.l'he curves represent the average for all animals fed a given level. ugzmicrogram. periment 3 in changing from 750 t0 1350 microgram carotene level. In Experiments 4 and 5 there was an almost immediate decrease in night blindness when carotene levels of 800 to 2500 micrograms were first supplied after the steers had become depleted but night blindness either increased or remained at about the same degree when these same levels were continued. _ The method of feeding a ration high in concentrates during the period of supplying the carotene levels may partially explain the persistence of night blindness on the carotene levels used in Experiments 4, 5, 6 and 7, the results of which are at particular variance with the California and Pennsylvania results. The tendency toward increased manifestation 0f vitamin A deficiency on fattening rations was perhaps shown nega- tively by the steers in Experiment 3, which were fed the 450 microgram carotene level until death. These steers when reaching advanced de- pletion declined in appetite and lost weight. Of the 5 steers involved all showed similar marked decline in appetite the first year and 2 died.- The other 3 partially recovered appetite, made gain for approximately one year, again failed in appetite, and in this decline 2 more died. The other steer again recovered and at the time of his fourth marked decline in appetite was sacrificed, because of urethral occlusion caused by uri- 32 BULLETIN NO. 630, TEXAS AGRICULTURAL EXPEEHMENT STATION nary calculi, after 993 days on the 450 microgram level. Hart and Guilbert (23) suggested a difference in the intensity of manifestations of vitamin A deficiency between cattle 0n 10W and on high energy intake in their discussion of vitamin A deficiency as related to reproduction in range cattle. While the evidence is not complete, difference in energy intake may be responsible for the fact that the California and Pennsyl- vania Stations were able to control night blindness with a level of caro- tene upon which cattle became completely night blind in Experiments 4, 5, 6 and 7. The effect of low temperature in increasing the minimum carotene re- quirement as reported by the Pennsylvania Station (l5) is of interest for in the main our results show that symptoms of vitamin A deficiency were intensified when the cattle were entirely exposed and when the daily maximum temperatures were within the range of 9O to 105 degrees Fahrenheit. Suffering from cold was also observed among severely de- pleted steers in Experiment 2. These observations were made during a period of 8 days at the Spur Station when the weather was cloudy and there was some rain and the minimum temperature ranged from 33 to 43 degrees Fahrenheit. It is logical to assume that suffering from vitamin A deficiency may be intensified by exposure to either high or low temperatures since animals severely depleted of vitamin A re- serves are in a weakened condition. EFFECT OF QUANTITY OF OAROTENE UPON GAIN AND FEED CONSUMPTION OF FATTENING CATTLE While the first three experiments showed that feeder cattle can be fattened on rations which are too low in carotene to sustain normal night 90 If / ,/// ,1’ Z .¢r' / so ZI/ , ' / u . / g / ,1 a " /’ /;/// Q I g0 70o I /l» 4 "5 4” / = / it 4‘ // I i‘; , 4" / g Y,” / < e00 -’ ' /i/ / I’ r Z ”’ / I /"/ lie a , en s00 //’ / g . / ‘Ground alfalfa hay. ffiround mllo heads used. 2917 meg per cwt. during deplvtion period (OILVLS JlNHWIHEIcIXH TVHILLTILOIHEJV SVXEIL T189 ‘ON NLLEITTHH VITAMIN A STUDY IN. FATTENING FEEDER CALVES AND YEARLINGS 35 Experiments 4, 5, and 7. In each experiment the fattening or test period began with the close of the depletion period, although one group of heifers used in Experiment 6 received 1000 micrograms of carotene in alfalfa meal from the start of the depletion period. The average final weights were secured at the feedlot and the carcass weights were the average weights of the warm carcasses. In Experiment 4, 1937-38, there was a general tendency for the steers fed the higher levels of carotene to consume greater amounts of feed, but the mean differences between levels were not great enough to be significant. In Experiment 5, 1938-39, the feed consumption Was rela- tively low for the 800 microgram level; however, ‘the average feed con- sumption for all levels was slightly lower than in Experiment 4. Ground alfalfa hay was used as the source of carotene in 1937-38 and dehydrated alfalfa leaf meal was used in 1938-39. The former was slightly unpala- table but not to such degree as to materially affect feed consumption. The latter was in instances obviously unpalatable and in the case of the steers receiving the 1500 and 2500 microgram levels feed consumption seemed to be reduced because of the amounts of alfalfa leaf meal neces- sarily fed. In the same year the 800 and 1000 microgram levels did not maintain normal well-being and less feed was consumed as a consequence. In Experiment 6, 1939-40, and Experiment 7, 1940-41, there was lit- tle difference in feed consumption between carotene levels. In these experiments the cattle not only showed less outward evidence of depletion than formerly, but dehydrated alfalfa leaf meal, high in carotene, was used so that only small amounts were needed to supply the respective levels of carotene. The heifers used in Experiment 6 consumed appre- ciably l-ess feed per 100 pounds live weight than the steers used in the other experiments; however, the heifers fattened more quicklyand were fed a more concentrated ration from the outset of the depletion period. The steers used in Experiment 7 consumed comparatively large amounts of feed per 100 pounds because of their light weight and perhaps because of the adequacy of their carotene levels, 1599 micrograms being the lowest level that was supplied. ' The differences noted in productive energy and digestible protein be- tween groups in the same experiment resulted from differences in feed con- sumption since the feeds were given as a standard mixture. The average rations supplied adequate protein but were slightly short in productive energy as compared to feeding standards for quick fattening (24). The efficiency of feed utilization was not consistent with the increase in carotene level in the four experiments. The 800 microgram carotene level was the least efficient in gain only in Experiment 5. In this in- stance Group 1, fedthe 800 microgram level, while consuming less feed made much lower gain than the other groups. The total feedlot gains for the fattening periods while shown in Table 9 are also presented in Figures 17, 18, 19 and 20. y Statistical analysis of the gains for Experiment 4, 1937-38, showed that a mean difference between carotene levels of 42 pounds was required 36 BULLETIN NO. 630, TEXAS AGRICULTURAL EXPERIMENT STATION //’ 25o / . /’ / x 1 r,"” ///Ir',’ 3 goo Z»’/ Z I » I d} lry f g ,2 ,//Z Z) t» "Z __*/Z Z) s ,»-_/»/l'_-_ll€—E//’ d 15o l! ’,'lj./ u v /// 7 o , > i‘. ' {n . t? /// P”. 10o ‘ 44,4“) 5 l,’ o (7 L a 1 egen : E/ ' 800 ug per curt. I / ‘ 1000 ug p r ewt. ____. 50 %/ 12s“ "5 sf.- “wt. _____ __ /’ 1500 u er cwt. ---- ‘ s P ,y:' 2000 ug per cwt. -—-+—- I7 O O 28 56 84 112 Days on Carotene Level Figure 17. Experiment 4, 1937-38. Gains of steers fed. various carotene levels. The curves represent the average of all animals fed a given level- ug: micrograms. 25o ,1 a Z § ~\ \ Cumulative Gain, Pounds F’ I“ 8 ‘<3 ‘\‘ \ \ ‘ \‘\\_v I r \\ \‘\ \\; Legend: /// 800 ug per cwt. ______ LUUU ug per cwt. i__ 5O _ 1%’ 1250 ug per cwt. ____ -.. ’/,/’ 1500 ug per cwt. i-‘ l, ’ , 2500 ug per cwt. ___+;. o s’ 23 56 84 112 Days on Carotene Level figure 18. Experiment 5, 1938-39. Gains of steers fed various carotene levels. The curve-s represent the average of all animals fed. a given level. ugzmicrograms. to be significant and 5E7 pounds to be highly significant; but only 31 pounds and 41 pounds, respectively, when the gains were corrected to a constant feed consumption. There appeared to be no consistent in- mn ' x ~ I 1 "4' 25c ‘ 5/1 0 /' a-"ZI I A I “ é zoo 5 O a. s‘ ‘i o 150 O > QC V I '5' § 100 p o Z 7 Z Legend: Z 1250 ug per ewt. -_--—- 5O 1500 u; yer cwt. —--—— /// _ 2500 ug per cwt. _____.. ’ Z5000 ug ger cwt. —-—— r X 5000 ug per evrt. —— +-— o r 2 ‘6 84 112 VITAMIN A STUDY IN FATTENING FEEDER GALVES AND YEARLINGS 37 4 , f I /// // 3 c: 39 5 O a. E ‘S u i g 34f ~14 P G I-Q E C) l6 I Legend: Levels fed after 800 ug per cvrt. -_--'- depletion - 106 days 1000 1.1g per cwt. —---—-' 1500 ug per cwt. -—-——-- From the Qeginning- 1000 ug per cvrt. -—--——— 56 84 112 140 108 196 Days on Experiment Figure 19. Experiment 6, 1939-40. Gains of heifers fed various carotene levels. The curves represent the average of all animals fed a. given level. ugzmicrograms. Days on Carotene Level Figure 20. Experiment 7, 1940-41. Gains of steers fed various carotene levels. The curves represent the average of all animals fed a given level. ugzmicrograms. - 38 BULLETIN NO. 630, TEXAS AGRICULTURAL EXPERIMENT STATION creasepin gain induced by increased quantities of carotene although the mean square of the diets showe existed between Groups 2 and 4 on bot between Groups 1 and 4 on uncorrec d thatsignificant differences in gain h, corrected and uncorrected basis, ted basis, and between Groups 3 and 4 on corrected basis. These- results indicate that neither feed con- sumption nor carotene level was responsible for the differences in gain. Clinical observations, how- ever, indicated that the carotene levels had a definite effect upon the general physical well-being of the animals. Analysis of the data for Experi- ment 5, 1938-39, indicated that the mean difference in gain must be as large as 44 pounds to be significant and 59 pounds to be highly significant on the uncor- rected basis and as large as 40 pounds and 54 pounds, respec- tively, on the corrected basis. Group 1 fed the 800 microgram level made significantly less gain thanthe groups fed the 1250, 1500 and 2500 microgram levels on the uncorrected basis, but when the gains were corrected for feed consumption all significant differences were eliminated. In Experiment 6, 1939-40, the“ gains were so nearly the same be- tween the carotene levels used that the experimental error in weigh- ing could have been responsible for greater differences. There was likewise slight difference in gains between the carotene levels used in Experiment 7, 1940-41. In each of the» four experiments there was marked uniformity in finish and carcass grades for the several groups of cattle which were fed. The ‘carcasses graded from Good to Choice and were noted for extremely white color of both external and internal fat. Figure 21. Pattened heifers used in Experiment 6, 1939-40. Fed for 206 days with IOU-day test period of carotene lev- els. Note excellent finish of all lots even though carotene levels used did not prevent complete night blindness. Upper Group 1—8CO micro- gram level. p Center Group 2—1000~ micro- gram level. Lower 63113111) 3-—1500 micro- gram level. Considering the general uniformity in the results in the four experi- ments in regard to gain and finish as indicated in Figure 21 it appears VITAMIN A STUDY IN FATTENING FEEDER CAL-VES AND YEARLINGS 39 that after the minimum amount of carotene needed to maintain the fat- tening animal in reasonably good health is supplied, larger amounts of carotene do not result in increased gains, increased finish, or higher carcass grades. Figure 22, showing Groups 1 and 5 from Experiment 7, illustrates the principal difference in outward appearance between the animals fed the higher and lower carotene levels in these four experi- ments. - Feeder calves fed levels of 800 to 1250 micrograms of carotene, after depletion of body reserves of vitamin A as indicated by the occurrence of night blindness, have fattened satisfactorily and have made normal gain in periods of 100 to 140 days, but in most in- stances have shown lack of nor- mal well-being. Those fed levels of 1500 micrograms have shown few symptoms of vitamin A defi- ciency other than complete night blindness, and night blindness has persisted upon levels of 2000 and 2500 micrograms. On levels of more than 2500 micrograms fed after depletion there was con- tinued improvement in degree of night blindness. In considering the minimum carotene level that Figure r22. Experiment 7, 1940-41. Up- should be supplied to fattening cat- per—-G1‘.’Oup 1, fed 1250 m1- . - - _ cr gra. leve 1_ Lower- tle aftei depletion the crucial con Gfoupms’ fed 5000 micrm sideration is the well-being of the gram level. Both grfillps are shown as fattened. after gattle. Night blindness, even of having been fed 249 days, severe degree, can be tolerated as the last 14° days °f whmh long as the cattle do not show {Yere SD91? HD0111 thle reslgefi- i 1V8 caro 8118 8V6 S. _ O 9 Other alarming Symptéms» but fififiothfiffiieekir £251 c222 when complete night bllndnes OC- and that Group 1 lacks nor- curs the feeder has no accurate m” alertness‘ means of determining degree of depletion. The carotene level should there- fore be above 1500 micrograms and we suggest 2000 to 2500 micrograms as the minimum requirement under Texas conditions in order to provide a reasonable margin of safety. The feeder cannot afford to risk failure of appetite, undue suffering from he-at, rough shaggy hair coat, or other factors involved in vitamin A deficiency that might affect the market- ability of the cattle. 40 BULLETIN NO. 630, TEXAS AGRICULTURAL EXPERIMENT STATION RELATION OF QUANTITY OF OAROTENE TO CAROTENE AND VITAIWIN A CONTENT OF LIVERS, BLOOD PLASMA, ‘FAT AND LEAN TISSUE Carotene and spectro vitamin A in the livers, blood plasma and fat of some of the cattle involved in these experiments were determined by spectrographic methods. The average carotene and spectro vitamin A Table 10. Carotene and. spectre vitamin A content of livers from cattle fed various levels of carotene, codliver oil, and roughages l Liver content DDIII Days on Treatments and carotene in- Experi- Number depletion take mcg. per cwt. daily sup- Days Caro~ Spectro ment animals r ration plied after depletion treated tene Vitam. A l f 1 179' ’ N0 treatment. Died _____________ __ ___ .2 2.1 I 1 190 10 cc codliver oil __________________ __ 34 .4 1.3 l 1 ' 152 j 25 cc codliver oil __________________ __ 72 .3 7.9 1 1 184 ’ 10 cc carotene in maize oil _______ __ 40 1.8 3.6 2 ___ 1 pound alfalfa hay ______________ -_ 224 1.3 6.4 1 ___ 2.5 pounds alfalfa hay ___________ _- 182 3.7 13.5 1 ___ 5 pounds alfalfa hay _____________ __ 224 2.5 17.0 1 ___ 8.7 pounds alfalfa hay ___________ __ 168 2.1 5.1 1A* 3 ___ 12 pounds hegari fodder_ ________ __ 168 1.4 . 6.1 4 ___ 37 pounds sumac silage_ _________ __ 175 3.5 28.4 f 1 381 No treatment _____________________ __ ___ .5 13.8 4 205 549 _________________________________ __ 166 .5 4.6 2 4 181 386 for 21 days, 1033 for 159 days“ 180 .6 4.1 I 4 226 800 _________________________________ __ 142 .7 ‘ 4.7 _ 4 1514 282 fo-r 30 days, 1751 for 181 days“ 211 .8 1 5.1 4 246 2364 _________________________________ __ 120 1.2 6.8 I 1 115 4.50—Died __________________________ __ 48.5 __ 1.6 s l 1 10s 450—Died ____________________ _; ____ _- 472 _- 2.1 l 1 101 450—D"ied __________________________ _ . 145 _ _ 1 4 .5 6‘ 5 J12 791 __________________________________ __ 100 -5 1.3 5 5 1015 836 _________________________________ __ 140 F l} 1.9 4 5 133 935 _________________________________ __ ‘ 140 .7 1.7 s 4. ___ 981 __________________________________ -- 212 .6 i 1.2 e 5 112 919a _________________________________ _- 100 .5 j it s 5 10a 128s ________________________________ --’ 140 .7 l 1.6 4 5 133 1410' ________________________________ __ 140 7 2.0 6 5 112 14811 _________ -1. ____________________ __ 100 .7 1.7 7 5 118 1837 ________________________________ __ 140 ~ .59 1.8 4 5 133 2196 ________________________________ __ 140 1.2 3.2 5 5 105 2485 ________________________________ __ 140 1.6 2.7 7 5 118 2830 ________________________________ __ 140 .9 2.4 7 5 118 3350' ________________________________ _- 140 1.2 2.7 7 4 118 5328 ________________________________ __ 140 1.37 4.7 *Steers from feeding trials conducted at Substation No. 9, Balmorhea, Texas, and from Substation No. 7", Spur, Texas, not in Vitamin A experiments and fed representative West Texas fattening rations. VITAMIN A STUDY IN FATTENING FEEDER CALVES AND YEARLINGS 41 content of the liver samples obtained in the several experiments are shown in Table 10. The carotene intakes shown in this table include the carotene supplied by both alfalfa and grain. Carotene and Vitamin A Content of Livers . The data obtained largely from single steers in Experiments 1, 1A, 2 and 3 may be mentioned. Of 4 steers from Experiments 1 and 3, which died from vitamin A deficiency, the average spectro vitamin content of livers was no lower than of steers fed carotene levels ranging from about 800 to 1800 micrograms in the last four experiments. The carotene and spectro vitamin A values of liver from steers fed daily allowances of 1, 2.5 and 5 pounds of alfalfa hay for 6 to 7 months in Experiment 1 and allow- ances of 8.7 pounds alfalfa hay, 12 pounds hegari fodder, and 37 pounds sumac silage for about 6 months in Experiment 1A, none of which showed outward evidence of depletion, are of interest when compared to the values shown by the variously depleted animals used in the later experi- ments. It is noted that the above values were equal to or higher in each instance than the average values found for steers receiving a caro- tene level of more than 5000 micrograms in Experiment 7. One steer in Experiment 2 which remained on the depletion ration for 381 days without becoming completely night blind but which had other symptoms of severe deficiency showed low carotene but a higher spectro vitamin A content of liver than the others. The record of this steer suggests differences between individuals in the utilization of carotene or of vitamin A for a given function. Of the other steers in Experiment 2 which had been variously depleted prior to the supply of the carotene levels there was a slight increase in carotene and spectro vitamin A with the increase of carotene level. For Experiments 4, 5, 6 and 7 the carotene levels supplied are arranged in ascending order in Table 10, Storage of spectro vitamin A, as was ex- peeled from the carotene levels fed, was low in all cases. The carotene and spectro vitamin content of the livers increased in most instances, when the quantity of carotene fed was increased. There was little dif- ference in the carotene and spectro vitamin A concentration in the livers on levels from 800 to 2000 micrograms. Above the 2000 microgram level the average values were higher. \ In Experiment 7 there was a very regular increase in both carotene and spectro vitamin A on the carotene levels supplied by both alfalfa and grain ranging from 1837 to 5328 micrograms. The individual de- terminations, however, showed considerable variation as illustrated in Table 11. The individual variation upon the same level together with the general trend toward an increase in carotene- and spectro vitamin A with increases in the supply of carotene indicate that it may be pos-l sible to determine from liver analysis whether an animal was suffering from vitamin A deficiency but that it is not possible to draw a sharp line of distinction between individuals on levels where they may or may not be affected. 42 BULLETIN NO. 630, TEXAS AGRICULTURAL EXPERIMENT STATION Table 11. Carotene and spectre vitamin A content of cattle livers (Elm. 7) Liver content, ppm Carotene micrograms —I—,——-——s———t—— Steer pericwt. daily, ure i ~DQ 15 k 1837 .54 J 2-1 4s l .47 1.6 34 J .40 1.5 .59 5' 1.. 21 J | 1.09 2.5 a J J 1.0a 1 as 37 ‘ 2830 .87 2.1 3 ' .80 2.0 7 J .69 J 2.5 .91 i z 4 18 I 1T5 2.5 24 1.11 3.4 2 3350 1.11 J 3.: 11 | 1.09 2.5 1 J .93 J 1.: ____€________J_?______. Average 1.22 J 2.7 l 28 I f -------------------------------------------- __ 1.54 8.6 12 J 5328 l - ___________________________________________ __ 1.33 1 2.1 29- ' 1 f ____________________________________________ __ 1.30 J 4,7 16 J l ____________________________________________ -- 1.30 \ 3.2 Average 1.37 J 4.7 Carotene and Vitamin A Content of Blood Plasma The carotene and spectro vitamin A in blood plasma were determined for part of the cattle used in Experiments 5, 6 and 7. Changes which took place in the carotene of the blood plasma are shown by the data obtained in Experiments 6 and 7, and are shown graphically in Figure 23. Four weeks after the heifer calves used in Experiment 6 were brought from the range and placed on the depletion ration samples of blood were drawn from 10 individuals selected from the group of 40 at random. The average carotene content of the plasma was 0.59 part per million. The animals were then divided into four groups of 10 each, one of which was fed a carotene level of 1000 micrograms per 100 pounds live weight daily from the outset while the other 30 were depleted of vitamin A. When the 3O had been depleted, samples of blood were drawn from 10 of them taken at random, a11d also from the 10 which had been fed the 1000 microgram level. The plasma carotene in the 10 depleted animals had dropped to 0.16 part per million and in the 16 head fed the 1000 microgram level to 0.32 part per million. The 30 depleted animals, in 3 groups of 10 each, were then fed for 100 days on levels "of 800, 1000, and 1500 micrograms and the other group was. continued on the 1000 microgram level. Then blood samples were drawn from 5 head in each group. The carotene concentration had risen from VITAMIN A STUDY IN FATTENING FEEDER CAL-VES AND YEARLINGS 43 the depletion average of 0.16 part per million to 0.19, 0.21, and 0.34 part per million in the groups fed 800, 1000 and 1500 micrograms caro- tene levels respectively, but had dropped from 0.32 to 0.27 part per million in the group fed the 1000 microgram level from the start. Exp briment 6, 1939-40 Depleticn Period Test period - 100 days Amend, 791 u; per cwt _____ 947 ug per cwr. 1015 Hg per cwt-_______ ‘ 993 ug per cwt. 1 moi ug per cWt-i ‘__ m 1O head §_ m i § iniii; ‘- Depleted _ so mad -__._ __.___ _ aii'_—§—._—_.~,—_-:;-zr_-_::-__ ____- Legend: 1837 n5 per cwt. _____ 2850 u; per cwt._____ \ 5350 u; per cwt._____ E328 ug per cvrt. a \ - —-— \ Experiment 7, 1940-41 Test: pe-iod - 140 days \ Eepletion period \ \ Plume l-nrotane Part \Por Million x \ _—I(’Z f/ I \ _?' n} \ ' Z _---' \ } ' ’/ _._.._---—"" p _/_':._-—~_:;'::ZI-——-—~-—-"?-'I—-‘ 0 4 E 0 l4 15 2. 2e 3o :54 3 Weeks on Experiment Figure 23. Carotene concentration ppm of blood plasma from cattle fed various carotene levels. The curves represent the average of all animals fed a given level. ugzmicrograms. In Experiment 7 the 10 initial blood samples, drawn at random, were secured within 5 days after the 50 feeder calves used were removed from the range. The average plasma carotene concentration was 3.42 part per million or 5.8 times as high as for the corresponding samples in Ex- periment 6. Since both groups of calves were approximately the same age and came from the same range upon which the rainfall had been practically equal in both years the three weeks’ difference in time on the depletion ration prior to blood sampling may account for the above differ- ence ininitial carotene content of blood plasma. This difference at least indicates that the carotene content of the plasma drops rapidly when ani- mals are changed from pasturage to rations practically free of carotene. When the calves became depleted ofvitamin A blood samples were again taken at random from 10 head and the average plasma carotene content was 0.24 part per million. At this point the calves were started on the carotene levels, and at the close of the test samples were drawn from 5 calves fed on each of the four higher carotene levels. From the aver- age of 0.24 part per million of plasma carotene at depletion the values rose to 0.47 on the 1500 microgram level, 0.56 on the 2500, 0.82 on the 3000, and 1.47 on the 5000 microgram level. Determinations of plasma 44 BULLETIN NO. 630, TEXAS AGRICULTURAL EXPERIMENT STATION carotene from 2 animals on each of three levels were also secured in Ex- periment 5. , When the determinations at the end of the test period in Experiments 5, 6, and 7 are combined, Table 12, a general increase in plasma caro- tene is shown with the increase in carotene levels from about 800 to 5000 micrograms, but the spectro vitamin A content was not consistent with the increase of carotene level. In comparing the results of night blindness and plasma carotene determinations, complete night blindness prevailed at all levels up to 1837 micrograms and was not entirely cor- rected at levels of 2500 to 3000 micrograms. Animals fed the latter levels, however, had some degree of night vision and at about 5000 micro-' grams 5 steers out of 8 showed normal night vision and the remaining 3 showed only 1° of night blindness after 140 days. Convulsions were also observed on levels of about 1500 micrograms or less. Table 12. Carotene and spectro vitamin A content of blood plasma at close of test from cattle fed various levels of carotene. Experiments 5, 6, and 7 i Carotene l Blood plasma,ppm Number of Test micrograms 1:————————-—— animals period i per Spcctro Experiment sampled days ‘a cwt. daily Carotene VitaminA Night Blindness 6, 1939-40» 5 100 l 791 l .19 -, l 5, 1938-39 2 140 1 s26 l .22 .25 | 6,193.94) 5 100 : 996 i .21 -- | Complete 6, 1969-46 5 100 l 1615* .27 __ l night blindness 1938-39 2 140 ~ 1226 .46 .25 | prevailed 6, 1939-40 5 10o 14s1 .34 _- | 7, 1940-41 5 140 1837 .47 .36 J 5, 19'3e-39 2 140 2485 .66 u .18 1 7, 1940-41 5 140 28310 .56 .34 L Some degree 7, 1940-41 5 140 “.50 ‘ .82 , .32 I of night vision 7, 194041 5 140 532s f 1.47 | .41 J *Carote~ne intake 94-7" micrograms per cwt. daily during 106-day depletion period. As previously noted, the heifers used in Experiment 6 at depletion, as indicated by the appearance of night blindness, showed 0.16 part per mil- lion of plasma carotene, while the steers in Experiment 7 showed a cor- responding average value of 0.24. The average plasma carotene content of the 20 animals involved in the two experiments was 0.20 part per mil- lion; however, there was considerable individual variation in the data with a range of 0.10 to 0.35 part per million. The plasma carotene level at which night blindness might_be expected to disappear after depletion and the supply of carotene was much less certain. At the close of the test period in Experiment 7, 6 steers showing more than 2° of night blindness averaged 0.54 part per million plasma carotene», one steer had slightly affected night vision at 1.77 part per million, and 3 which showed normal night vision averaged 1.08 part per million. Of 31 cat- tle involved in the three experiments and fed levels ranging from about 800 to 1800 micrograms of carotene for periods of 100 to 140 days after depletion, the average level of carotene in the plasma was .30 part per VITAMIN A STUDY IN FATTENING FEEDER OALVES AND‘ YEARLINGS 45 million. The data from these experiments are hardly sufficient to estab- lish definite levels at which night blindness may appear or disappear or at which health may be impaired; however, it is indicated that few symp- toms of vitamin A deficiency other than night blindness are likely to be observed when the plasma carotene level exceeds .30 part per million. Moore (12) found that an intake of about 16 micrograms of carotene per pound of body weight daily maintained plasma carotene at 0.2 micro- gram per milliliter, prevented night blindness and maintained a fair state of health in Holstein calves. He also noted that night blindness followed when the carotene value fell below about 0.13 microgram per milliliter. Davis and Madsen (25) stated that certain preliminary find- ings indicate that the critical level of carotene in the plasma is about “.25 microgram per milliliter, and for vitamin A in the same sample 0.16 microgram per'milliliter; and noted that at or above these levels animals do not usually show characteristic clinical symptoms of vitamin A deficiency. Keener et al (15) in a study of carotene in calf nutrition observed that when blood carotene fell below .0175 milligram per 100 milliliters of whole blood in Holstein calves, vitamin A deficiency symb- toms were frequently found . ‘ Carotene and Vitamin A Content of Fat and Rib Cuts Analyses were made of the rendered caul fat from 19' of the steers used in Experiment 7, 1940-41. The carotene and spectro vitamin A de- terminations were made by methods similar to those used for liver. The vitamin A potency was determined by feeding to rats, in comparison to carotene dissolved in oil. The average results for the four carotene levels which included samples from 19 fattened steers are shown in Table 13. Table 13. Carotene, spectro vitamin A, and vitamin A potency of caul fat 0f steers used in Experiment 7, 1940-41 Part per million Vitamin A g l l Number Carotene level ‘ of l micrograms | Spectro potency, I. U. animals l per cwt. daily i Carotene Vitamin A per gram l 5 1837 ‘l .07 .65 .9 5 2830 .12 .75 1.2 5 3350 I .09 .62 .9 4 5328 .11 .86 1.1 The vitamin A content of the caul fat was very low, about 1 Inter- national Unit per gram. The animals receiving 5328 micrograms caro- tene per 100 pounds of live weight daily stored slightly more vitamin A in the caul fat than those fed 1837 micrograms, the difference being almost in the limit of error. The carotene content and spectro vitamin A content were only slightly greater in the caul fat from the animals receiving the higher level. Part of the spectro vitamin A probably con- sisted of compounds not vitamin A which absorb light in the same region 46 BULLETIN NO. 630, TEXAS AGRICULTURAL EXPERIMENT STATION of the spectrum. This was shown by the 10w vitamin A potency of the fat When it was measured biologically. Biological vitamin A assays of 12th rib cuts from the carcasses of the steers fed the 1250, 2500 and 5000 micrograms carotene levels supplied by alfalfa meal, or respective intakes of 1599, 2830 and 5328 micro- grams of carotene, including carotene supplied by grain, in Experiment 7 were made. One composite sample of external fat and another of lean tissue were prepared from each of the respective carotene levels. The vitamin A content expressed as International Units per 100 grams of meat tissue for the respective samples were: Carotene Vitamin A Content Experiment micrograms per cwt. daily External Lean tissue with fat intermuscular fat l 1599' 33 14 7 2830 33 l6 l 532s 96 as It is noted that the values of the lean tissue with intermuscular fat are approximately 1-2 to 1-3 those of the external fat. The value of the ex- ternal fat was’ low even from the steers on the 5000 microgram level as compared to values of 660 International Units per 100 grams of fatty _ tissue from rib cuts of cattle fattened on grass and 420 International Units in similar material from cattle fed grain and hay in dry lot as reported by Mohler (26). CONDITIONS UNDER WHICH VITAMIN A DEFICIENCY MAY OCCUR When feeds low in carotene such" as bleached hays or fodder, straw or cottonseed hulls form the roughage portion of the dry lot fattening ration feeder calves or yearlings may become depleted of body reserves of vitamin A before they can be fattened. The light feeder calves used in Experiments 8, 9, and 10, Table 1, were quickly depleted when fed cottonseed meal with sorghum roughage which had been more than a year in storage. In all of the experiments reported here feeder calves or, yearlings became depleted and showed more or less‘ advanced symptoms of vitamin A deficiency when cottonseed hulls were fed as the roughage ‘with the sorghum grains and cottonseed mea-l. In a feeding trial at the U. S. Experiment Station, Big Spring, Texas (27) 27 out of 40 calves, average initial weight 450 pounds, on a fattening ration consisting of ground thresh-ed milo, cottonseed meal and new crop sumac silage of apparent good quality became night blind after 130 days. Many other in- stances of vitamin A deficiency have been observed in dry lot fattening. Hart and Guilbert (23) have reported that under dry range conditions forage becomes deficient in carotene and that vitamin A deficiency may develop on the range following long and severe drouth, which deficiency VITAMIN A STUDY IN FATTENING FEEDER CALVES AND YEARLINGS 47 resulted in reduced calf crop, difficulty in calving, and calves weak at birth. There are several practical considerations concerning the occurrence of vitamin A deficiency in fattening cattle. The time required for feeder cattle to become depleted of body reserves of vitamin A when- fed rations. low in carotene in dry lot is affected by the amount and distribution of the rainfall during their development on the range. Range forages when green and growing are high in carotene and cattle grazing upon them accumulate reserves of vitamin A. The carotene content decreases as the plants grow older and the quantity is quite low in weathered grasses and forages so that the feeders may come off of the range with low reserves of vitamin A. In this case the time required for depletionin dry lot on rations low in carotene is less than for feeders removed from good range following a season of favorable rains. Light young feeder calves have less storage of vitamin A reserves than heavy calves or yearlings origi- nating from the same range. According to the results of these experi- ments heavy feeder calves can be expected to become depleted on rations low in carotene within about 90 to 120 days in dry lot while light feeder calves may become depleted within 5O to 8O days depending in both 1n- stances upon the kind of range from which they were removed. Yearling feeders are less likely to become affected by vitamin A deficiency before they can be fattened in dry lot than calves for they can be fattened in less time and can be expected to have greater reserves of vitamin A than calves. Cattle remaining on the Texas ranges are not likely to suffer from vitamin A deficiency except during unusually long periods of drouth because of their ability to store reserves of vitamin A, the comparatively large amounts of grass eaten, the comparatively small amount of carotene‘ nec- essary to prevent deficiency condition, and because, as shown in Table 14, numerous range plants contain fair amounts of carotene. During severe drouth there is not only a lack of green feed but a short- age of total feed which results in a shortage of nutrients and minerals as well as of carotene. Under such extreme conditions the supplemental feeds should supply carotene in addition to other needed nutrients and necessary bulk. It is obvious that any range practice which conserves water for grass growth during the dry months is beneficial from the standpoint of carotene supply. Dickson (28) and associates have shown that contour listing increased the quantity of green grazing and hence increased the supply ,of carotene. ' With reference to the crude carotene content of some Texas feeds, in- cluding grasses and other range plants shown in Table 14, a wide range in the carotene content of the same kind of feed, as for alfalfa, may be noted. Alfalfa hay showed 116 to 0.6 part per million carotene while de- hydrated alfalfa leaf meal ranged from 304‘ to 53 parts per million. The alfalfa hay containing only 0.6 part of carotene per million had been stored .. .for 3 years. Marked variations in the carotene content of hays and feeds depend- ing upon the method of curing and time in storage have been shown by 48 4 BULLETIN NO. 6,91), TEXAS AGRICULTURAL EXPERIMENT STATION Table 14. Crude carotene content of some Texas feeds, including grasses, and forage plants, dry basis* Description Crude Carotene parts per million Alfalfa hay- ______________________________ _.~_ 116, 58, 51, 34, 27, 20, 14, 11, 9, 8, 6, 4, 3, 0-6 Alfalfa leaf meal, dehydrated _____________ -- 304, 283, 2'79, 269, 265, 254, 250, 2'22, 2W, 184i» 168» 147, 139, 112, 107, 97, 70, 66, 53 Alfalfa stem meal __ 65, 9 Bermuda hay__ 5, 2 Bermuda grass, dormant __________________ __ 2 Bermuda grass, fresh green ________ __ __-- 413, 361, 281, 187, 174 Bufialo- grass, dormant ____________ __ ---_ 94, 34, 31, 26, 25, 22, 19, 15-. 7, 4 Buffalo grass, fresh green ________________ __ 254, 226, 2107, 179', 169, 167, 155, 146 Cactus, spineless 33 Cactus, prickly pear _______________________ _- 6 Corn shuck _________________________________ -- .7 Clover meal__ ~ 18 Clover, bur, fresh green ___________________ __ 364 Clover, sweet, fresh green _________________ __ 418 Dallis grass, dormant- ____________________ -_ 15 Dallis grass, fresh green __________________ -_ 495, 372, 227 Grama grass, hairy, dormant _____________ -_ 18, 8, 8 Grama grass, hairy, fresh green __________ __ 122 Guajillo leaves, fresh green ________________ __ 105 Johnson grass, fresh green ________________ __ 366, 365 Kafir silage____ 35, 22, 18, 15, 9, 8, 5, 5, 4, 3, 3, 2 Liveoak leave-s, fresh green _______________ __ 133, 55 Mesquite leaves, fresh green _______________ __ 44 Milo fodder _________________________________ __ 2 Needle grass, dormant ____________________ __ 13, 9 Peanut hay- _______________________________ __ 45, 39, 16 Postoak leaves, fresh green _______________ __ 114, 81 Prairie hay, largely bluestem _____________ __ 32, 19, 18, 18, 14, 11, 9, 8, s, 3 Rhodes grass hay __________________________ __ 2 Rhodes grass, fresh green- _______________ __ Rescue grass, fresh green __________________ __ 406 Rye, Italian, fresh green __________________ __ 373 Sorghum hay or fodder, sumac ___________ -- 4, 3, 2, 2, 2, 2, 1, 1, 0.8 Sorghum silage, sumac ____________________ _- 51, 43, w, e1, 30, 2s, 20, 18, 15, 14, 5, 4, 2 Sotol leaves, fresh green __________________ __ 42 Soto] bulb, fresh- _________________________ -_ 2 Sudan grass hay ___________________________ _- 9, 6, 4 Cottonseed meal ___________________________ __ 0'7 Feterita, threshed grain ___________________ __ ,3 Hegari, threshed grain ____________________ __ .4 Hegari grain screenings_ __________________ __ .9 Kaflr, threshed grain ______________________ _- .4 0.4, 0.3 Milo heads ground _________________________ __/ 6 2 Milo threshed grain ________________________ u] *As reported by Kemmerer et al. (310) and analyses by Division of Chemistry, T.A.E.S. many research workers. Fraps and Treichler (29) reported that vitamin A content of feeds decreased in accordance wtih the length of time in storage and that alfalfa leaf meal lost 50 per cent_and yellow corn 30 per cent of the vitamin A potency in 5 months under storage conditions. Yellow corn, when fresh, may contain about 5 units of vitamin A potency per gram. The ground milo heads used in the experiments contained at the most .69 part per million of carotene, ground threshed milo ranged from .2 to .4 part per million. Sumac silage, as shown in Table 14, ranged from 51 to 2 parts per mil- lion of carotene on dry basis. Kafir silage showed a range of 35 to 2 parts per million of carotene. The higher values for both of the above silage-s were shown for the samples secured just after the trench silos VITAMIN A STUDY IN FATTENING FEEDER CALVES AND YEARLINGS 49 were opened in the fall. With the successive samples taken at 14-day intervals until the silos were emptied in early summer there was a steady decline in carotene value from start to close of the feeding period. There are some indications that the carotene when contained in small amount in hays and fodders may be utilized by fattening cattle to less extent than the carotene in alfalfa. It is obvious from Table 14 that the quantity of a feed required to supply a given carotene level depends upon the carotene content of the feed. In Experiment 1, one pound of good quality alfalfa hay fed per head daily was sufficient to protect feeder steer calves from vitamin A deficiency for more than 224 days; however, the micrograms of carotene supplied in that instance was not known. In the later experiments levels of about 2500 micrograms of carotene prevented the manifestation of symptoms of vitamin A deficiency other than a degree of night blindness. Assuming a required level of 2500 micrograms per 100 pounds live weight daily for a 500 pound steer we find, since a pound contains 453.6 grams and one part per million equals one microgram per gram, that one pound of alfalfa hay containing 27.5 parts carotene per million would supply 12500 micrograms of carotene or 2500 micrograms per 100 pounds of steer. Should it be desired to supply an 800 pound steer 5000 micro- grams of carotene per 100 pounds of live weight it would be necessary to feed about 3.2 pounds of alfalfa containing 27.5 parts of carotene per million. As previously noted, light calves may be expected to show sign of de- pletion about 50 days after their removal from the range and placement in dry lot on rations low in carotene. It has also been noted that severe vitamin A deficiency condition should not be allowed to develop. Fortu- nately the onset of vitamin A deficiency condition can be easily recog- nized by observing the cattle after dark. Night blindness, practically al- ways the first symptom, appears before the cattle suffer damage in re- gard to fattening. Even after the appearance of night blindness the de- ficiency can be corrected in fattening cattle by feeding good quality al- falfa, other green feeds, or high vitamin A potency cod liver oil. Only small amounts of alfalfa hay or other curatives are required to prevent this condition and response to treatments is usually rapid and easily recognized. ' SUMMARY AND CONCLUSIONS Cattle fed rations very low in carotene in dry lot for a considerable length of time lose their reserves of vitamin A and will, if retained on such rations, die unless carotene or vitamin A is provided. In seven experiments conducted from 1934 to 1941 with 310 feeder cat- tle ranging from 3 to 16 months of age at the time of being placed in the feedlot and fed rations low in carotene, the time required for deple- tion of body reserves of vitamin A, as indicated by night blindness, ranged from 45 to 268 days. Young animals became depleted in less time 50 BULLETIN NO. 630, TEXAS AGRICULTURAL EXPERIMENT STATION than older animals. In drouthy years less time was required for deple- tion than in favorable years. Young animals have less storage of vitamin A than older ones and consequently exhaust their reserves more quickly, while animals which have had green forage high in carotene accumulate greater reserves than those which have had dry forage which is low in carotene. Night blindness was practically always the first symptom of vitamin A deficiency that could be observed. Watering at the eyes, sluggishness, complete night blindness, nasal discharge, suffering from solar heat as characterized by panting and slobbering, convulsive seizures, body swellings, day blindness, loss of appetite, loss of weight and finally death were other progressive symptoms of vitamin A deficiency which were observed. At the point of visible body swellings the subcutaneous tissues were found to show an edematous infiltration. In cases of ad- vanced vitamin A deficiency this condition led to the condemnation of the carcasses. A carotene level of 450 micrograms was not sufficient to sustain life during extended periods of feeding. Steers supplied this level after de- pletion fattened but their carcasses showed a generalized edema sufficient to’ warrant their rejection as a food. Gains were continued until the animals showed marked symptoms of vitamin A deficiency and losses in weight did not occur until there were marked losses in appetite. These results show that carotene is not needed in the fattening ration for the production of gain as long as the body reserves of the animals meet their requirments for well-being. It is only when the body reserves of vitamin A become depleted that fattening cattle show symptoms of vita- min A deficiency. Curative treatments for vitamin A deficiency consist in increasing the quantity of carotene in the ration through green growing feeds, legume hays of high quality such as alfalfa, or the supply of vitamin A by the administration of cod or other fish liver oils high in vitamin A. Green forage or hays, particularly alfalfa of pea green color, are excellent sources of carotene. In the usual periods of time required for fattening beef cattle the addition of 1 to 2 pounds of good quality alfalfa hay to the ration may usually be expected to prevent the occurrence ofvitamin A deficiency. If the condition has been allowed to develop it can usually be remedied by feeding 2 to 4 pounds of good quality hay per head daily or by daily dosing with 50 to 100 cc of commercial grade cod liver oil, for a period of 2 to 3 weeks. Carotene levels of about 1500 micrograms supplied by either alfalfa hay or dehydrated alfalfa leaf meal to fattening feeder calves were not sufficient to prevent the development of comp1ete.night blindness in test periods of 100 to 140 days after depletion. Of 115 head fed from about 800 to 1800 micrograms of carotene, ‘99 became completely night blind. Of 23 head fed 2000 to 2500 micrograms, 4 became completely night blind and the remainder were partially night blind. On 3000 micrograms fed after depletion the tendency was toward improvement in night vision. VITAMIN A STUDY IN FATTTENINGAFEEDER GALVES- AND YEARLINGS 51 In one test with 5000 micrograms‘ of carotene 5 steers out of 8 regained normal night vision within 140 days. Carotene as high as 1250 micro- grams permitted day blindness to develop and a few instances of stag- gering gait and convulsions were observed at the 1500 microgram level. Quantities of 800 and 1000 micrograms of carotene fed per 100 pounds live weight daily or one pound of alfalfa hay did not induce significantly greater gain than was made by calves fed the unsupplemented depletion ratio_n, but did delay the occurrence of night blindness. Carotene when supplied in larger amount than necessary to prevent severe depletion did not produce significant increase in gain. There was practically no storage of carotene or spectro vitamin A in the livers of cattle fed up to 1800 micrograms carotene. Slight storage took place on 2500 and 3000 micrograms and while even more storage occurred on 5000 micrograms the amount was still very small. The average carotene and spectro vitamin A content of rendered caul fat from cattle fed carotene up to 5000 micrograms was low. Composite samples of external fat and of lean tissue with intermuscular fat from irib cuts of steers fed about 1250, 2500 and 5000 micrograms carotene twere likewise low in vitamin A in comparison to the values found in similar samples from steers fattened on grass. Lean tissue with inter- imuscular fat contained only 1-3 to 1-2 as much vitamin A as external “fat. Higher vitamin A potency in the body fat resulted from increases in carotene level, but it is apparent that a relatively high carotene intake ilis necessary for an appreciable amount of storage. I There was a regular increase in blood plasma carotene on levels‘ of in- ‘take ranging from about 800 to 5000 micrograms although the incre- llments were small from about 800 to 1800. Plasma carotene apparently {takes a sharp initial drop when cattle are first removed from pasturage grand fed a ration low in carotene. With continued depletion the decline Eis apparently slow with night blindness appearing when the carotene {drops to about .20 part per. million of blood plasma. The carotene requirement for fattening beef cattle is that quantity which will allow animals to maintain satisfactory physical condition during the fattening period involved. In these experiments 1500 micro- Egrams per 100 pounds live weight daily allowed in most instances satis- factory feed consumption and gain but to allow a margin of safety a level of 2000 to 2500 micrograms is recommended. Sorghum roughages, straws, and some other roughages and grains ‘frequently do not contain enough carotene to prevent the occurrence of vitamin A deficiency in cattle fed for long periods in dry lot. Periodic checks for night blindness may be made after the first 50 days in the .case of young feeder calves fed on rations low in carotene. If a vitamin A ideficiency is then indicated, it can be remedied with alfalfa hay or green feeds. One to 2 pounds of good quality alfalfa hay per head daily in- cluded in an otherwise low carotene ration usually supplies a 500-pound feeder animal 2000 to 6000 micrograms carotene per 100 pounds live weight. .IY'}"Y' 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 423. 24. 25. 26. 27. 28. 29. 20. ' 31. BULLETIN NO. 630', TEXAS AGRICULTURAL EXPERIMENT‘ STATION LITERATURE CITED ‘ Connell, J. H., and Carson, J. W. Sta. Bul. 41. Burns, John C., and Metcalfe, T. P. 1912. A test of the relative values of cottonseed meal and silage, and cottonseed meal and cottonseed hulls for fattening cattle. Tex. Agri. Expt. Sta. Bul. 153. Curtis, R. 1938. Cottonseed meal, origin, history, and research. p. 79. The Robert S. Curtis Publishing Company, Raleigh, N. C. Curtis, R. S. 1925. Present status and results of cottonseed meal feed- ing investigations. Record of Proceedings, Amer. Society of_ Animal Prod., July 1927. Halverson, J. 0., and Sherwood, F. W. 1930. 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