Zflififééiiace. CAMPUS- TEXAS AGRICULTURAL EXPERIMENT STATION A. B. CONNER, DIRECTOR COLLEGE STATION, BRAZOS COUNTY, TEXAS BULLETIN NO. 473 DECEMBER, 1932 DIVISION OF DAIRY HUVSBANDRY Sorghum Silage as a Source of Vitamin A for Dairy Cows AGRICULTURAL AND MECHANICAL COLLEGE OF TEXAS T. O. WALTON, President STATION STAFF? Administration : A. B. Conner, M. S., Director R. E. Karper, M. S., Vice-Director Clarice Mixson, B. A., Secretary M. P. Holleman, Chief Clerk J. K. Franckloyv, Asst. Chief Clerk Chester Higgs, Executive Assistant Howard Berry, B. S., Technical Asst. Chemistry: . S. Fraps, Ph. D., Chief; State Chemist E. Asbury, M. S., Chemist F. Fudge, Ph. D., Chemist . C. Carlyle, M. S., Asst. Chemist . L. Ogier, B. S., Asst. Chemist . J. Sterges, M. S., Asst. Chemist Ray Treichler, M. S., Asst. Chemist W. H. Walker, Asst. Chemist Velma Graham, Asst. Chemist Jeanne F. DeMottier, Asst. Chemist R. L. Schwartz, B. S., Asst. Chemist C. M. Pounders, B. S., Asst. Chemist Horticulture : S. H. Yarnell, Sc. D., Chief Range Animal Husbandry: J. M. Jones, A. M.. Chief B. L. Warwick, Ph. D., Breeding Investiga. S. P. Davis, Wool-Grader I**J. H. Jones, B. S., Agent in Animal Husb. Entomology: F.‘ L. Thomas, Ph. D., Chief; Entomologist H. J. Reinhard, B. S., Entomologist R. K. Fletcher, Ph. D., Entomologist W. L. Owen, Jr., M. S., Entomologist J. N. Roney, M. S., Entomologist J. C. Gaines. Jr.. M. S., Entomologist S. E. Jones. lVl. S., Entomologist F. F. Bibby, B. S., Entomologist "E. W. Dunnam, Ph. D., Entomologist **H. W. Moreland, B. S., Asst. Entomologist C. E. Heard, B. S., Chief lnswcctor C. Siddall, B. S., Foulbrood Inspector KIM-IQ???) State Veterinary Science: ‘ *M. Francis, D. V. M., Chief H. Schmidt, D. V. M., Veterinarian‘ **F‘. P. Mathews, D.V.M., l\.'l.S., Veterinarian R. A. Goodman, D. V. M., Veterinarian Plant Pathology and Physiology: J. J. Taubenhaus, Ph. D., Chief W. N. Ezekiel, Ph. D., Plant Pathologist Farm and Ranch Economics: L. P. Gabbard, M. S., Chief W. E. Paulson, Ph. D., Marketing TTC. A. Bonnen, M. S., Farm Management Z£**W. R. Nisbet, B. S., Ranch Management . C. Magee, M. S., Farm Management Rural Home Research: Jessie Whitacre, Ph. D., Chief Mary Anna Grimes, M. S., Textiles Elizabeth D. Terrill, in. A., Nutrition Soil Survey: **W. T. Carter, B. S., Chief E. H. Templin, B. S., Soil Surveyor A. H. Bean, B. S., Sol} Eiwrveyoi" R. M. Marshall, B. S., Soil Surveyor Botany: V. L. Cory, M. S., Acting Chief Swine Husbandry: Fred Hale, M. S., Chief Dairy Husbandry: O. C. Copeland, M. S.. Dairy Husbandman Poultry Husbandry: R. M. Sherwood, M. S., Chief J. R. Couch, B.S., Asst. Poultry Husbandman Agricultural Engineering: H. P. Smith, M. S., Chief Main Station Farm: G. T. McNess, Superintendent Apiculture (San Antoninl: H. B. Parks, B. S., Chief A. H. Alex, B. S., Queen Feed Control Service: _ F. D. Fuller, M. S., Chief James Sullivan, Asst. Chief Breeder S. E. McGregor, B. S.. Foulbrood Inspector S, D, Pearce, Secretarv Agrflflflmyi J. H. Rogers, Feed Inspector E- B- Reyllolds, Ph- D» Chief K. L. Kirkland, B. S., Feed Inspector R- E- Karpel‘, M- 3-, AKAPOHOmiSt S. D. Reynolds, Jr., Feed Inspector P. C. Mangelsdorf, Sc. D., Agronomist P. A. Moore, Feed Inspector D- T- Killmlgh, M- 3-, Agronomist E. J. Wilson, B. S., Feed Inspector Pllblicatiwls! H. G. Wickes, D. V. M., Feed Inspector A. D. Jackson, Chief SUBSTATIONS No. 1, Beeville, Bee County: R. A. Hall, B. S., Superintendent No. 2, Lindale, Smith County: P. R. Johnson, M. S., Superintendent No. 9, Balmorhea, Reeves County: J. J. Bayles, B. S., Superintendent No. 10, College Station, Brazos County: R. M. Sherwood, M. S., In Charge **B. H. Hendrickson, B. S., Sci. in Soil Erosion L. J. McCall, Farm Superintendent **R. W. Baird, B. S., Assoc. Agr. Engineer N0. 3, Angleton, Brazoria County: R. H. Stansel, M. S., Superintendent H. M. Reed, M. S.. Horticulturist No. 4, Beaumont, Jefferson County: R. H. Wyche, B. S., Superintendent **H. M. Beachell, B. S., Junior Agronomist No. 5, Temple, Bell County: Henry Dunlavy, M. S., Superintendent C. H. Rogers, Ph. D., Plant Pathologist H. E. Rea, B. S., Agronomist S. E. Wolff, M. S., Botanist **H. V. Geib, M. S., Sci. in Soil Erosion **H. O. Hill, B. S., Junior Civil Engineer No. 6, Denton, Denton County: P. B. Dunkle, B. S., Superintendent **I. M. Atkins, B. S., Junior Agronomist No. 7, Spur, Dickens County: R. E. Dickson, B. S., Superintendent B. C. Langley, M. S., Agronornist No. 8, Lubbock, Lubbock County: D. L. Jones, Superintendent Frank Gaines, Irrig. and Forest Nurs. No. 11, Nacogdoches, Nacogdoches County: H. F. Morris, M. S., Superintendent **No. 12, Chillicothe, Hardeman County: **J. R. Quinby, B. S., Superintendent **J. C. Stephens, M. A., Asst. Agronomist No. 14, Sonora, Sutton-Edwards Counties: W. H. Dameron, B. S., Superintendent I. B. Boughton, D. V. M., Veterinarian W. T. Hardy, D. V. M., Veterinarian O. L. Carpenter, Shepherd **O. G. Babcock, B. S., Asst. Entomologist No. 15, Weslaco, Hidalgo County: W. H. Friend, B. S., Superintendent S. W. Clark, B. S., Entomologist W. J. Bach, M. S., Plant Pathologist J. F. Wood, B. S., Horticulturist No. 16, Iowa Park, Wichita County: C. H. McDowell. B. S., Superintendent L. E. Brooks, B. S., Horticulturist N0. 19, Winterhaven, Dimmit County: E. Mortensen, B. S., Superintendent **L. R. Hawthorn, M. S., Horticulturist Teachers in \the School of Agriculture Carrying Cooperative Projects on the Station: G. W. Adriance, Ph. D., Horticulture S. W. Bilsing, Ph. D., Entomology V. P. Lee, Ph. D., Marketing and Finance D. Scoates, A. E., Agricultural Engineering A. K. Mackey, M. S., Animal Husbandry *Dean, School of Veterinary Medicine. **In cooperation with U. S. Department of Agriculture. S. Mogford, M. S., Agronomy F. R. Brison, B. S., Horticulture W. R. Horlacher, Ph. D., Genetics J. H. Knox, M. S., Animal Husbandry A. L. Darnell, M. A., Dairy Husbandry TAs of December 1, 1932. i TOn leave. IIn cooperation with Texas Extension Service. Butter fat from a cow fed only cottonseed meal and hulls over a long period 0f time contained only about 21/; units of vitamin A to the gram. Cows restricted to cottonseed meal and hulls suffered from night blindness and become very sick; two of them died, two were cured by administration of cod liver oil, and one by fresh green grass. The low vitamin A content of the butter fat, the cure of the cows by cod liver oil, and the symptoms of the diseases show that these cows did not receive enough vitamin A. Cows fed sor- ghum silage in addition to the cottonseed meal and hulls produced butter fat low in vitamin A and variable in that constituent. The cows showed symptoms of night blindness and one of them had symptoms typical of deficiency of vitamin A. The sorghum silage fed in large quantity did not furnish enough vitamin A to produce butter fat of high potency and apparently furnished not quite enough vitamin A for maintenance and good health. Cows receiv- ing pasture in addition to the cottonseed meal, hulls, and sorghum silage produced butter fat high in vitamin A and containing about 9 times as much per day per cow as that from the cow fed sorghum silage. A tentative estimate that the cow received 106,000 units a A day in vitamin A but produced only 1960 units a day in the butter, indicated that the dairy cow has a high requirement for vitamin A, either on account of destruction during the process of digestion or high maintenance requirements during lactation or both. * Summary CONTENTS Introduction Plan of Experiment - Description of Silage Effect on Vitamin A Content of Butter Fat Relation of Quantity of Vitamin A Fed to that Produced Daily in Butter Fat Vitamin A Content of the Sorghum Silage and of the Feed Eaten by‘ the Cow __ Effect on Health of Animals References BULLETIN NO. 473 DECEMBER, 1932 SORGHUM SILAGE AS A SOURCE OF VITAMIN A FOR DAIRY COWS O. C. COPELAND AND G. S. FRAPs Silage is fed to milk cows quite extensively throughout the leading dairy sections of the United States and is recognized as one of the cheapest and most satisfactory succulent feeds available in large quantities. Silage is usually fed during that part of the year when pasturage is poor or unavail- able; however, some dairymen feed silage the entire year to cows which have access to good pastures at least a part of the year. Dairy cows have the capacity for storing large quantities of vitamin A (11) so that the large reserve of this vitamin stored up in their bodies during the pasturing season in addition to that furnished in the hay, silage, and other feeds will usually carry them through the dry-lot feeding period to the next pasturing season without any noticeable effects of an under- supply of vitamin A on the health of the animal. Since silage is prepared from green feeds, it would be natural to assume it to be high in vitamin A. Very little definite information is available con- cerning the vitamin A content of silage. Scheunert (8) lists silage made from green fodder along with green feeds, hay, and sugar-beet leaves as a good source of vitamin A. He states that “ensiled green feeds contain vitamin A at the most, in slightly smaller amounts, if any, than the green feeds not ensiled,”_and “that the source of vitamin A for our animals are green feeds and silage made therefrom and hay.” Henry and Morrison (6) list corn silage as a good source of vitamin A. Halverson and Sherwood (4) found that rations of cottonseed meal and corn silage did not maintain good health and normal reproduction in dairy cows. They state that “the neces- sary nutritive factors for supplementing this deficient ration, both for maintenance and normal reproduction, are carried in butter fat or cod liver oil and in calcium carbonate or steamed bone meal. The data of reproduc- tion indicate a lack of fat-soluble A in the ration.” Corn stover, timothy hay, and even alfalfa hay in moderate amounts also did not seem to supply sufficient vitamin A. The original object of this investigation was to ascertain if cottonseed meal fed in combination with other feeds for long periods of time in large quantity to dairy cows, would have a deleterious effect upon their health or production of milk due to any toxic effect of the gossypol present or to any other possible injurious constituent. It became evident during the progress of the experiment that the disturbances of health of the animals receiving cottonseed meal and hulls were chiefly due to deficiency of vitamin A, and that some of the animals receiving the ration containing sorghum silage did not get enough vitamin A for best results.. This showed that in this ration the cottonseed meal and _hulls as well as the sorghum silage did not provide sufficient vitamin A. Since the sorghum silage was a feed which was naturally expected to furnish sufficient quan- tities of vitamin A but which Was found to be deficient, most importance was attached to its deficiency. 6 BULLETIN NO. 473, TEXAS AGRICULTURAL EXPERIMENT STATION Plan of Experiment In the original plan of the experiment three groups of cows were used. * One group was fed on cottonseed meal and hulls in a dry lot, without ‘ access to green feed or silage.. Another group was fed on cottonseed meal, cottonseed hulls, and sorghum silage and had access to pasture. The third group was fed cottonseed meal, cottonseed hulls, and sorghum silage. As this group was the one in which the silage was fed, it is the one especially significant in this work. This group consisted of four pure-bred Jerseys and one grade Jersey. .=. Three of them were mature cows, one was four years old, and one slightly over two years old, milking with her first calf. On December 20, 1929, these five cows were placed in a lot free from all vegetation and fed sorghum silage, cottonseed hulls, and cottonseed meal. An addition of 2%% of ground limestone and 1% of salt was made to the cottonseed meal. As there is not sufficient lime in either sorghum silage or cottonseed hulls to balance the 2% to 3 per cent‘ of phosphoric acid in the cottonseed meal, * the limestone was used to prevent a large excess of phosphoric acid. The ¢ cottonseed meal was fed at the rate of one pound for every 2% pounds 3.’ of milk produced per day during the lactation period and 4 pounds per cow per day during the dry period. Fresh water, block salt, and shelter were p, available at all times. Records were kept of the exact amount of feed ~ fed to each group of cows, but as this information is not essential to the a‘ present discussion, it is omitted. Description of Silage The silage fed during this investigation consisted mainly of sorghum silage, although a small amount of corn silage was fed from August 1930 to the latter part of December, 1930. The silage fed during the first three months of the experiment had been in the silo slightly over two years. The remainder of the silage used in the investigation was 3 weeks to 14 months old. The silage used was produced during the years 1927, 1929, 1930, and 1931. Two silos were used with intervals of about two weeks between filling. The silage was harvested when most of the grain was in the hard dough stage. All of the silage fed apparently had become well fermented, as judged by the color and odor of the silage. Effect on Vitamin A Contentlof Butter Fat Samples of the butter fat from one of the cows fed on cottonseed meal, cottonseed hulls, and silage were secured on April 13, 1931, after the cows had been on experiment 479 days. Samples from one cow of each of the other groups of cows were also taken. Additional samples were taken on other dates as shown in Table 1. The vitamin A content |Of the butter fat was determined by Mr. Ray Treichler, of the Division of Chemistry (3) using the Sherman-Munsell method (9), as modified by this station (2). The results are expressed in units of vitamin A, a unit being the amount 7 2&5 . k i ! www5w>< s 3:: £5 E25 _ o...” _ 2 :55. 5 . . . w 8:5 MM... . 5.2a; _ CH2 _ S .5552 .............. =32 .3 2.5 5&2. MMHWMM. “up. “$55M C 1 _ __ o 5 _ m: .>oZ ............................................... zwwfi dZ Boo dmnmm wan .23: 4x25 wowmflouuoO 55w Y $5 _ _ _ mush; R $5 5.: g5 5 o6 _ mu i554 _ Emma .< . . . _ mm 5w w 5 so ow M g5 5.: com: ma“ _ 2 Z554 omwim W55 615.54 .?o5..:55 flowmmmfimfi D 2a 5 2 .5 2:. ,7 9m § 5 £552 ...... 1:55 .5 .555. 55%.: .5. .02 30o .325 5.5 .25: :52: wwwéosoo 23$ W“. Mm _ mm. _ 3S m N t 5 @5595» . mm i: < _ .. M“... w...“ “w. 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Q 555w»? 5mm 505:5: 555M no: 55A 5m 9.55.5 w: wow flomaamaowom. , >50: @5559. mfiwaw wmwwo>< : Z 3:557: minho v55 vwiwown v5.55 $5045.: wmwflm E5:m.~om 5: 55w 5am .535: 5: ¢ 5:55»? new 3mg wifiwamfifiafinl: 2:59 r 8 BULLETIN NO. 473, TEXAS AGRICULTURAL EXPERIMENT STATION required to produce an average gain of three grams a week for 8 weeks on rats previously depleted of the vitamin. As shown in Table 1 the butter fat produced by the cows fed on the cottonseed meal, cottonseed hulls, and silage contained much less vitamin ‘c A than the butter fat produced by the cows which received pasture in addi- tion to the feed mentioned above. The quantity of vitamin A varied from one-tenth to a little more than one-third of the vitamin A in a normal butter fat. The cows fed on cottonseed meal and cottonseed hulls with- out the silage produced butter fat very low in vitamin A. The addition of silage increased the vitamin A in the butter fat of the cows, but the amount ' was still very much lower than that contained in normal butter fat. The above data show that the amounts of vitamin A provided by cotton- seed meal and hulls to dairy cows are sufficient to place only low quantities of vitamin A in the butter fat.‘ The sorghum silage also furnishes insuf- ficient vitamin A for the butter fat. That is to say, the sorghum silage cannotbe relied upon to provide the quantity of vitamin A necessary to produce butter high in vitamin A or of normal potency in vitamin A. The vitamin A stored in the bodies of the cows at the beginning of the experi: ment had no doubt been depleted, and the sorghum silage, cottonseed meal, and cottonseed hulls furnished insufficient amounts. Relation to Quantity of Vitamin A fed to that Produced Daily in Butter Fat The quantity of vitamin A produced in the butter fat can be estimated from the data secured regarding the number of units in the butter fat and the quantity of butter fat produced at the time the samples were taken. These results are given in Table 2. The cow fed cottonseed meal and hulls produced daily butter fat containing 340 units of vitamin A. The one receiving cottonseed meal, cottonseed hulls, and silage produced 1960 units a day, and the one receiving pasture in addition to the cottonseed meal, hulls, and silage produced 17,240 units per day. It has already been pointed out that vitamin A in the butter of the cow receiving silage varied con- siderably, as ‘is evident from both Tables 1 and 2. On an average the addition of silage to the meal and hulls increased the output of vitamin A in the butter fat 1,620 units per day, while silage and pasture together increased it 16,940 units a day. The addition of the pasture to the ration of cottonseed meal, cottonseed hulls, and silage on an average increased the vitamin A output 15,320 units a day, a very high increase. It seems reasonable to conclude that cottonseed meal, cottonseed hulls, and sorghum silage do not furnish sufficient vitamin A to produce butter of high potency if they are fed for long periods of time without access to pasture. Vitamin A Content of the Sorghum Silage and of the Feed Eaten by the Cow Since the experiment was not planned as a study of vitamins and the silage was expected to furnish sufficient amounts of vitamin A, no esti- mation was made of the vitamin A content of the silage during the first i, A! <2 '. . z é § a SORGHUM SILAGE AS A SOURCE OF VITAMIN A FOR DAIRY COWS 9 part of the experiment. After it was discovered that the ration was defi- cient in vitamin A, a sample of the silage was secured and tested by the Sherman-Munsell rat method already mentioned. This sorghum silage in the original moist condition was found to contain 5 units of vitamin A per gram, which is about 15 units per gram of dry matter. Although the data are insufficient for exact estimates, we believe that we are justified in dis- cussing the data and drawing tentative conclusions. An average of 52.3 pounds of sorghum silage per cow was given to the silage group daily. It is estimated that 10 per cent was wasted, which would leave 47 pounds consumed daily per cow. With 5 units of vitamin A to the gram of silage, the total consumption would be 106,000 units of vitamin A a day. The cow from which the butter was secured Weighed 750 pounds. Silage is well known to be variable in composition according to the variety of the plant, stage of growth at which cut, manner of handling in the silo, and other factors, and no doubt varies in content of vitamin A. It is probable that some of the vitamin A in the green feed is destroyed during the fermentation which forms the silage, after which the vitamin A is lost more slowly. A decrease during storage we have found to occur with dried foods, such as corn, dried milk, and alfalfa. The portions of the silage referred to were taken beginning December 30, 1931 and may have contained more vitamin A than older silage. Definite information regarding this point is desirable. The estimated consumption of 106,000 units of_ vitamin A a day in addi- tion to that in the cottonseed meal and hulls was accompanied by the pro- duction in the butter of only 1,620 units a day, as an average, which may be compared with 15,320 units a day assigned to pasture. This apparently low utilization of vitamin A of the sorghum silage might be due to several causes. The estimate of the quantities of vitamin A, based upon a very small amount of data, may be too high. However, even if the consump- tion were only one-third of the estimate, the percentage utilized would still be very low. It is possible that the fermentation in the digestion of the silage destroys part of the vitamin A. This seems a possible hypothesis. According to Hauge and Aitkenhead (5), enzymes are the important fac- tor in the destruction of vitamin A in the field curing the alfalfa. The enzymes might destroy the vitamin A during the fermentation which occurs when silage is formed. A third hypothesis is that the cow has a high requirement for vitamin A to maintain the body. While this enters into the matter, it is questionable if the maintenance requirements are suffi- ciently high to account entirely for the low utilization of the vitamin A. The subject clearly requires more study, which we have under way. Effect on Health of Animals All five of the animals fed on cottonseed meal, hulls, and silage had dis- turbances of health, which might be ascribed to a deficiency of vitamin A. After having been in dry-lot feeding for about five months, some of them showed signs of hemeralopia, or night blindness. This trouble was inter- mittent among all of the animals on experiment; at times the vision was 10 BULLETIN NO. 473, TEXAS AGRICULTURAL EXPERIMENT STATION apparently normal and at other times they appeared very blind after dark. McCollum (7) is of the opinion that this eye trouble frequently occurs as the result of a deficiency of vitamin A in the ration. Converse and Meigs ( 1) found calves fed on over-ripe timothy hay were weak and often blind. After having been on experiment for about four months all the cows fed silage were extremely nervous and excitable when handled outside of their lot or milking barn. Slight nasal discharges were observed in all of the animals; however, this condition was also intermittent, lasting only for a day or two at a time. Cow No. 42 apparently “broke down,” as she showed symptoms typical of vitamin A deficiency such as swollen legs, loss of appetite, hemeralopia, loss in body weight, and skin lesions. Sherman and Smith (10) report evidences of cutaneous malnutrition in rats deprived of vitamin A, as shown by scabbiness of the tail or ears, sores on the nose, thin bushy‘ hair, and sore feet. This cow showed all of these symptoms. ' Figure 1 shows a picture of this animal taken on April 30, 1932. On the 374th day of the experiment, she fell to hen knees three or four times, . trembling markedly; her condition was very critical for about 2 weeks, when she began to improve al- though she remained on the same ration. Traces of her present symptoms first became noticeable after she had been on experiment about two years; her condition finally died. After about the fifth month of dry-lot feeding all these animals were observed licking the dirt, showing signs of craving something not present in their ration. Except for cow No. 42, the other cows on the silage ration Fig. 1. This cow had been fed in dry-lot on were in a’ high degree of flesh and a ration of cottonseed meal, hulls, and sorghum ShQWed 1'10 IOSS Of appetite, SWOHGH silage for 833 days at the time this picture . 1 was taken. Note the unthriftywondition and legs: lameness: or Scabblness: a ' Swdle" legs- though all had night blindness as ' mentioned above. The disturbances mentioned above might, to some extent, be ascribed to an insufficient quantity of vitamin A in the ration. However, the symp- toms are by no means conclusive. It might be thought that it is due to the gossypol. The evidence is rendered more satisfactory “by com- parison with the animals fed cottonseed meal, and cottonseed hulls with- out silage or green feed. All of these cows became weak, some so weak that they were unable to stand. Two of them died. One was fed daily 21/2 pounds of fresh green grass, and after complete recovery the fresh green grass was omitted from her ration and she again became sickand died. The two others were fed cod liver oil, one at the rate of 250cc. a day and the other 125cc. a day; both recovered rapidly. The cod liver oil made the change gradually became worse and she. SORGHUM SILAGE AS A SOURCE OF VITAMIN A FOR DAIRY COWS 11 for the better in a markedly short time of one or two day; aid caused complzte recovery in a month. Cod liver oil supplies both vitamin A and vitamin D, but the cows all had an abundance of bright Texas sunshine and as sunshine is the equivalent of vitamin D, they probably received suffi- cient vitamin D for maintenance. Since the animals were cured by cod liver oil or green grass containing‘, vitamin A, it thus is positively estab- lished that the cows fed cottonseed meal and hulls suffered from a defi- ciency of vitamin A. The night blindness and other disturbances of health of the cows fed sorghum silage in addition to the cottonseed meal and hulls would indicate that the amount of vitamin A they received was at times sufficient for mfzintenance, but at other times fell slightly below maintenance requirements. Halverson and Sherwood (4) in ‘i-Qhe extensive work already referred to, concluded that a ration of cottonseed m;al and hulls was deficient in vitamin A and in other respects, and that corn stover, corn silage, and possibly timothy hay supplied vitamin A on the border line for- maintenance for dairy cows. These conclusions are similar to those reached above. ' SUMMARY Five Jersey cows were fed in dry-lot on a ration of cottonseed meal containing 21/2 per cent of limestone, 1 per cent of salt, and sorghum silage and cottonseed hulls ad libitum. The silage contained approximately 5 units of vitamin A per gram and was the chief source of vitamin A. Other groups of cows were fed cottonseed meal and hulls only, While another, group received pasture in addition to cottonseed meal, hulls, and silage. 'l‘he butter fat from one of the cows fed cottonseed meal and hulls aver- aged 2.5 units of vitamin A per gram. The butter fat from one of the cows fed silage in addition to cottonseed meal and hulls contained only ' 2 to 12 units of vitamin A, while that from cows on pasture contained as much as 33 units. The cow on cottonseed meal and hulls, on each of the days the samples were taken, produced fat containing, on an average, 340 units; that receiv- " ing silage in addition produced 1960 units a day; that on pasture produced 17,280 units a day. Sorghum silage, cottonseed meal, and cottonseed hulls did not furnish enough vitamin A to produce butter fat of high potency in vitamin A. Pasture supplied sufficient vitamin A to produce butter fat of high potency in vitamin A. ' The cows after prolonged feeding on cottonseed meal and hulls became very weak; two of them were cured by administration of cod liver oil and one by feeding fresh green grass. As cod liver oil is a carrier of vitamins A and D, and as vitamin D was supplied in abundance by sunshine, it. is evident the cows were suffering from a deficiency of vitamin A and that the cottonseed meal and hulls did not supply sufficient vitamin A for main- tenance of the cows. 12 BULLETIN NO. 473, TEXAS AGRICULTURAL EXPERIMENT STATION The cows that received sorghum silage in addition to cottonseed meal ~. and hulls exhibited symptoms of night blindness and other disorders, which 7 indicated that the ration might not quite supply sufficientvitamin A for g good health. Based upon the available data, an estimate is made that the cow receiv- 5 ing sorghum silage consumed about 106,000 units a day of vitamin A, ,1 although it produced only about 1960 units a day in butter, which was 1 low in vitamin A. While more data are needed, the results indicate that the dairy cow has a high daily requirement for vitamin A, either on account 1_ of destruction of vitamin A during the process of digestion or high main- ;_. tenance requirements during lactation, or both. REFERENCES 1. Converse, H. T. and Meigs, E. B., 1932. Some disasters in reproduc- tion and growth caused by low-quality hay. Proc. Am. Soc. Animal Production, 24:141. 2. Fraps, G. S., 1931. of corn. Tex. Exp. Sta. Bul. 422. 3. Fraps, G. S. and Treichler, R., 1932. amin A content of butter fat. Ind. & Eng. Chemistry, 2421079. 4. Halverson, J. O. and Sherwood, F. A., 1930. Investigations in the feeding of cottonseed meal to cattle. Bul. 39. 5. Hauge, S. M. and Aitkenhead, W., 1931. ing upon the vitamin A content of alfalfa. 6. Henry, W. A. and Morrison, F. B., 1923. Feeds and Feeding. Eighteenth Edition. The Henry-Morrison Company. 7. McCollum, E. V., 1922. The Newer Knowledge of Nutrition. Edition. The McMillan Co., New York. 8. Scheunert, A., 1927. Uber den Vitamingehalt der Silage futter. Ztschr. Tierzucht u. Zuchtungsbiol., 8349. 9. Sherman, H. C. and Munsell, H. E., 1925. The quantitative determina- tion of vitamin A. Jour. Amer. Chem. Soc., 47 :1639. 10. Sherman, H. C. and Smith, S. L., 1931. The Vitamins. Second Edi- tion. The Chemical Catalog Company, Inc., 419-4th Ave., 29th St., N. Y., U. S. A. 11. Steenbock, H., Sell, M. T., and Nelson, E. M., 1923. Fat Soluble Vitamin. Storage of the Fat Soluble Vitamin. Jour. Biol. Chem, 56:327. The effect of artificial dry- Second Variations in vitamin A and chemical composition , Quantitative variations in vit- V’ N. c. Agr. Exp. Sta. Technical Jour. Biol. Chem., 93.657. * .. . 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