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 http://www.archive.org/details/cu31924003206954 
 
Cornell University Library 
 QP 535.1 1R8 
 
 The significance of iodine in the feedin 
 
 3 1924 003 206 954 
 
 r at 
 
 t&he 
 Significance of 
 
 II € ID II N IE 
 
 in the Feeding 
 of Livestoc\ 
 
 QWO 
 
 By 
 GEORGE B. ROTHWELL, B.S.A. 
 
 / 
 
C£. I tell 
 
 i<rri 
 
 X HE Significance of Iodine in 
 the Feeding of livestock" has been prepared and 
 written by George B. Rothwell, Dominion Animal 
 Husbandman of the Experimental Farms System in 
 Canada. Mr. Rothwell is outstanding as an investi- 
 gator and authority on livestock problems and this 
 article of his is most timely. It summarizes the work 
 and findings in connection with the feeding of Iodine 
 to Livestock as carried on by Experimental Farms 
 throughout the Dominion. 
 
 G*-»q 
 
The Significance of Iodine in the 
 Feeding of Live Stoc\ 
 
 In the much discussed field of live stock mineral requirements and 
 deficiencies, there is one constituent, more recently in the limelight, 
 as yet imperfectly understood in its action by the scientist, and not 
 sufficiently appreciated by the stockman, — iodine. Most of us are 
 familiar with the therapeutic or medicinal value of tincture of iodine, 
 iodoform, Lugol's solution of iodine, etc. Most of us are familiar 
 with the potassium iodide treatment for goitre in human beings and 
 with the fact that such goitre is more frequently found in iodine 
 deficient areas. Not all are familiar with the fact that, while only 
 the most minute traces of iodine are required for proper animal func- 
 tionings, even partial interference with or diminution of this require- 
 ment or reserve, may be reflected in most undesirable . conditions, 
 quite apart from goitre. Here the road between cause and effect 
 is frequently so long and indirect as to prove difficult of travel. Just 
 how far reaching is the effect of iodine deficiencies or excesses on the 
 nutrition and proper functioning of live stock is not known at present. 
 Speaking strictly as a practical stock man and admitting a relatively 
 superficial knowledge of animal physiology and pathology, it would 
 seem to the writer that in this element we have, not a panacea in 
 any sense, but an agent, firstly, with preventive, and secondly, with 
 curative properties that make its consideration well worth while. 
 
 Certain general facts concerning the use of iodine with live stock 
 that have come to the writer's attention from trial and experiment, 
 and from the findings of scientists and research workers, are as 
 follows : 
 
 1. That there are marked iodine deficient areas throughout 
 
 Canada. 
 
 2. That the administration of iodine with certain kinds of stock 
 
 apparently has desirable influences even where iodine de- 
 ficiency, as generally recognized, does not appear to exist. 
 
 3. That the source of iodine as it may be administered to live 
 
 stock is immaterial (see note) and the choice governed 
 rather by economy of purchase and ease of administration. 
 
 Page Three 
 
THE SIGNIFICANCE OF IODINE IN THE FEE DING OF LIVE STOCK 
 
 4. That what may be termed the optimum (or best all round) 
 
 quantities of iodine for definite uses with the different kinds 
 of stock have not been definitely ascertained as yet. So 
 small may these quantities be as to seem ridiculous. In 
 many cases of deficiency , the tiniest quantities supplied 
 regularly produce remarkable results. 
 
 5. That while the curative qualities of iodine in its various forms 
 
 are well known to the stockman, the prophylactic (or pro- 
 tective) properties are equally as important, and, up to the 
 present, less recognized. 
 
 6. That iodine, particularly where there is a deficiency, produces 
 
 its most potent results, as so far disclosed, where adminis- 
 tered in small quantities regularly to the female during the 
 period of pregnancy. 
 
 7. That the method of administration *is even more immaterial 
 
 than the source, provided the animal body absorbs it 
 regularly and in accordance with its minute requirements. 
 
 Note: — Iodine, of course, is found in certain toxic combina- 
 tions. These are not commonly available. It is conveniently 
 available where used as an accessory to the normal iodine 
 content of the ration, as potassium iodide (the most 
 commonly used form), tincture of iodine, Lugol's solution 
 of iodine, etc. 
 
 The Practical Application. Let it be emphasized once more 
 that iodine is no cure-all. From the foregoing generalities such might 
 be inferred. After reading this preamble, the following paragraphs 
 concerning the known powers of iodine in a protective sense mainly, 
 may prove of interest. 
 
 First, a consideration of the practical forms of iodine ad- 
 ministration : 
 
 1. Potassium iodide as relating to this discussion is by far the 
 
 more generally used of all forms of iodine. 
 
 2. Commerical salt, either in the block or fine form, may be 
 
 purchased. This, in general, is said to contain in the vicinity 
 of .02 per cent potassium iodide crystals, or double the 
 quantity found in the iodized table salt now commonly 
 in use for human consumption. 
 
 3. Potassium iodide crystals may be purchased at any druggists, 
 
 supply houses, or certain of the live stock co-operative 
 associations and prepared at home for administration, 
 
 Pa g e Four 
 
THE SIGNIFICANCE OF IODINE IN THE FEEDING OF LIVE STOCK 
 
 (a) by mixing it with salt, preferably fine; (b) by diluting 
 definite quantities of potassium iodide with definite quan- 
 tities of water, thus making what is known as a stock 
 solution, and mixing small quantities of this with feed daily, 
 or at regular intervals; (c) by diluting small quantities with 
 drinking water at stated regular intervals. Certain of the 
 above methods are particularly suited to each of the 
 different classes of stock from the standpoint of practic- 
 ability of administration. 
 
 With Sheep. Iodine administered to the pregnant ewe will 
 definitely control goitre in lambs, where such abnormality exists, 
 notably in known iodine deficient areas. Apparently it has a marked 
 but not so thoroughly proven effect on falling or loose wool. Apparent- 
 ly, too, it has a most beneficial effect where for no distinct reason weak 
 lambs, over-grown, flabby lambs or premature births are common. 
 
 Method of Administration. In the form of an iodized salt. Where 
 such is used the year 'round, it is quite likely that a commercial 
 iodized salt will be effective. Where an iodized salt is used during the 
 period of pregnancy only, results secured on certain of the Experi- 
 mental Farms would make it appear doubtful as to whether .02 per 
 cent potassium iodide (as in commercial salt) is sufficient. On the 
 Experimental Farm System, where experimental work has been carried 
 on in this connection for a number of years, the following practice is 
 followed — dry 100 pounds fine commercial salt; spread it thinly and 
 evenly on a canvas or tarpaulin; dilute from 2 to 4 ounces of potassium 
 iodide crystals in a pint or so of water; sprinkle or spray this solution 
 evenly over the layer of dry salt, which will take up the liquid; mix 
 thoroughly; keep dry and place before the ewes during the winter. 
 It is not definitely known whether these quantities (2 to 4 ounces) 
 are optimum. It has been shown that four ounces is effective under a 
 variety of conditions, although likely in excess for general use. It has 
 been shown in one instance that one ounce per hundred pounds is not 
 fully effective in controlling goitre. On the other hand, one pound of 
 potassium iodide to one hundred pounds of salt has been used with 
 sheep without toxic effect. This was done for comparative experi- 
 mental evidence, the iodide was greatly in excess of requirement, the 
 mixture therefore very expensive and its use exposed the ewes to 
 unnecessary danger. Possibly the happy medium of three ounces per 
 hundred pounds of salt would be generally effective, although likely in 
 excess of any actual requirement. Anyway, it is safe, reliable and 
 effective. It will be seen, however, that there is a considerable range 
 between the iodine content of commercial iodized salt (.02 per cent) 
 and the home mixture recommended (from .125 to .25 per cent). 
 
 It is true that Hanzlik, Talbot and Gibson, in the Archives of In- 
 ternal Medicine (Vol. 42, No. 4, Oct., 1928) state that "the objections 
 which have been raised against the prolonged administration of iodine 
 in small doses are conspicuously unsupported by trustworthy evi- 
 
 P ag e Five 
 
THE SIGNIFICANCE OF IODINE IN THE FEEDING OF LIVE STOCK 
 
 dence." The results of their own experiments on rats given the rela- 
 tively heavy dose of 1 milligram of iodide per head per day, for periods 
 varying between one-seventh and seven-twelfths of the span of life, 
 indicated that such treatment was not merely not detrimental but on 
 the contrary was beneficial along various lines. The writer is informed, 
 also, that at the Rowatt Research Institute in Aberdeen, in recent 
 experiments designed to gauge the tolerance of various animals for 
 iodine, increasing doses were fed for several months (three to seven) 
 until pigs were getting the enormous quantity of 5 grams, calves 4, 
 sheep .3, and poultry .3 grams of iodine per head per day without show- 
 ing any toxic effects. Nevertheless in some cases there may be danger 
 in materially increasing the quantities here suggested for regular or 
 prolonged use, and for purposes of economy, if no other, the potassium 
 iodide should be kept down as close to the effective point as possible. 
 
 For Swine. Swine are subject to certain conditions that would 
 seem to be controlled through the administration of potassium iodide 
 to the pregnant sow. 
 
 The occurrence of hairless litters is a phenomenon familiar to swine 
 breeders generally. Although partly caused, it is probable, by defective 
 feeding and management of the sow during pregnancy, the primary 
 cause has been well indicated as due to a deficiency of iodine. The most 
 familiar result is hairless litters, although blind pigs, flabby, soft, over- 
 grown individuals and other abnormal manifestations may be present. 
 
 The phenomenon of hairless litters is baffling in that it may occur 
 without warning. With conditions normal last year, this year's litters 
 under apparently identical conditions may be seriously affected. 
 Why? No reason can be advanced other than that there is known to 
 be a comparatively wide variation in the mineral content of crops 
 from year to year. In districts recognized as deficient in iodine, 
 hairless litters are common, reaching the proportions of an epidemic 
 in certain years. Where hairless litters are apprehended, and where 
 there is a frequent occurrence of this trouble, the use of potassium 
 iodide is a reliable preventive. In that this condition may not occur 
 •regularly year to year, it is difficult to ascertain whether the desired 
 result is due to the treatment. However, where other factors are 
 similar and experimental methods applied, sows fed with protective 
 intent give normal litters, whereas untreated sows show affected or 
 partially affected litters. 
 
 As the treatment is simple, comparatively cheap and reliably 
 effective, it should be administered as a routine practice wherever the 
 trouble is common. It consists of the following:— dissolve one ounce 
 of iodide of potassium in two quarts of water. Give one tablespoonf ul 
 (or half a fluid ounce) of this solution once a day mixed in the feed or 
 water of every six females of the smaller breeds, ewes and sows. A 
 larger dose should be given to cows, one or two teaspoonfuls of the 
 
 Page Six 
 
THE SIGNIFICANCE OF IODINE IN THE FEEDING OF LIVE STOCK 
 
 above solution to each animal according to its size. Treatment should 
 begin soon after breeding and continue until the young are born. 
 
 Litters from sows so fed (where other items of management have 
 been properly taken care of) are almost invariably strong and vigor- 
 ous. Although apparently definite results have been obtained by 
 certain American investigators, in the way of increased gains in the 
 feeding of market pigs, attributed to the administration of minute 
 quantities of potassium iodide, these results have not been borne 
 out so far in tests conducted on the Experimental Farms. 
 
 For Horses. Every farmer horse-breeder is familiar with joint 
 ill, navel ill (pyremic arthritis) of foals. To all intents and purposes 
 it is incurable. Vaccine treatments have been recommended and are 
 fairly reliable, depending apparently on the origin and history of the 
 vaccine. The disease has baffled breeders and practitioners for years. 
 
 Without attempting to give a detailed account of findings, suffice 
 it to say that on a number of Experimental Farms (notably at the 
 Central Experimental Farm, Ottawa) where vaccines have been used 
 regularly, careful disinfection made a feature and preventive hygiene 
 followed, according to the best known methods, — this trouble per- 
 sisted in its appearance. This much is claimed and no more, — in 
 nearly every instance the disappearance of joint ill cases has coincided 
 with the commencement of administration of small quantities of potas- 
 sium iodide to the in-foal mare. No reason so far can be offered. No 
 definite claim for effectiveness is made. 
 
 The fall foal rarely, almost never, is afflicted with joint ill 
 probably due to the fact that the mare works all summer, spends 
 much of her time outdoors, and generally enjoys the benefits of a 
 healthy, hard muscled, normal functioning, well scavenged system, 
 all of which is reflected on the foetus. These are undoubtedly the 
 prime requisites to the development of a healthy and therefore 
 resistant (to disease) foal. These, coupled, with the use of a clean- 
 breeding stallion (and by this term is meant a horse with no apparent 
 hereditary or genital taints, and with the same constitutional charac- 
 teristics as mentioned in the case of the mare). No medical treatment 
 will overcome faulty management, but it should be used as an added 
 protection superimposed on practical hygiene. 
 
 The suggested treatment is as follows, — for spring-bred mares 
 (the fall-bred mare would not seem to require it) , commencing in 
 October or November, give from one-half to a level teaspoonful of 
 potassium iodide crystals in drinking water on the first and fifteenth 
 of each month, — or twice monthly. Simply dilute the crystals or 
 powder in a little warm water and pour into the drinking water. 
 Continue until foaling time. Here it has been suggested to the writer 
 that the quantity may be considerably in excess of requirements, 
 minute though it appears, and that one-quarter teaspoonful is 
 
 Page Seven 
 
THE SIGNIFICANCE OF IODINE IN THE FEEDING OF LIVE STOCK 
 
 sufficient. On no account should it be increased, therefore. If desired, 
 the same quantities might be administered in weekly instalments 
 and proportionately smaller doses. 
 
 Foals from mares so treated, aside from showing no trace of 
 infection, have been singularly rugged and strong. The initial 
 difficulty at Ottawa has been to hold them down long enough to 
 properly disinfect the stump of the navel cord with tincture of iodine, 
 —again the old reliable iodine! The stump is not ligatured or tied 
 with tape as sometimes recommended. 
 
 Incidentally, it might be stated that the writer is familiar with 
 several practitioners who now employ this method of protection, 
 recommend it, and find it reliable in practice. Reports mostly favour- 
 able, come from breeders. Even from Scotland reports have been 
 received stating that disappearance of the trouble in certain Clydes- 
 dale studs has coincided with the adoption of the treatment described. 
 Joint ill is much more generally prevalent in Scotland than in Canada. 
 
 Let it not be inferred, however, that this treatment is 100 per 
 cent sure. A few cases of joint ill have been noted with iodine 
 treated mares. 
 
 For Cattle. A consideration of the question as applied to dairy 
 cattle has been left to the last, largely for the reason that less definite 
 information would seem to be available concerning the protective 
 influence of iodine toward certain ailments affecting this class of stock. 
 
 This much would appear as well authenticated. Goitre or "big- 
 neck" in calves, frequently a serious condition, may be controlled by 
 the administration of iodine to pregnant cows. With cattle generally, 
 the most practical means of administration is through the medium 
 of salt mixtures. Commercial iodized salt, used regularly, will likely 
 prove satisfactory. Where it is thought necessary to use it during the 
 pregnant period only, and particularly where the treatment is directed 
 toward the control of persistent appearance of goitre in calves, — a 
 home mixture of from 2 to 4 ounces per hundred pounds of salt might 
 prove more reliable. In that some cows consume comparatively small 
 quantities of salt, the method of treatment given under the heading 
 "Swine," in which it will be noted treatment for cows is mentioned, 
 could be used. This method is more certain in application than where 
 iodized salt is used, but less convenient and practical of administration. 
 
 Throughout the foregoing it will be seen that iodine would seem to 
 exert a powerful influence for good during the period of pregnancy. 
 What protective effect might the administration of iodine have in the 
 case of genital infections of cattle causing premature birth, retained 
 membranes, sterility and other troubles? Much would be given by 
 the writer at this juncture to claim definitely on well-proven grounds 
 that such administration was effective. Such claims have been made, 
 but are not well authenticated as yet. This much would seem quite 
 
 P age Eight 
 
THE SIGNIFICANCE: OF IODINE IN THE : FEEDING OF LIVE STOCK 
 
 clear to anyone who has given much study to modern research in the 
 matter of genital disease; no man need expect a rapid return to normal 
 conditions in a herd affected with some form of genital infection (com- 
 monly known under the general name of infectious or contagious abor- 
 tion) simply by the regular administration of iodine to his cows. What 
 might result through the use of this treatment in the way of disease 
 resistance, when applied over a period of time, yet remains to be 
 seen. However, there is one aspect of the question as yet not definitely 
 mentioned, although having a direct and obvious bearing on each con- 
 sideration taken up in these paragraphs. To illustrate, the following 
 quotation is taken from a recently issued pamphlet as representing a 
 summary of work done in connection with iodine (Iodine for Live 
 Stock, by Frank Ewart Corrie, B.Sc.) : "The. influence of iodine in 
 establishing and maintaining the natural powers of resistance has been 
 referred to by many research workers and demonstrated repeatedly in care- 
 ful laboratory experiments." Unquestionably, in the experience of the 
 Central Experimental Farm, lambs, pigs, foals and calves from iodine 
 treated mothers would seem to have increased strength and vitality, 
 and therefore likely increased resistance to disease. Such would seem 
 to explain the effectiveness of the treatment in the case of foals, with 
 reference to an infection in nearly all cases acquired at or immediately 
 following birth. Strong foals are enabled to resist infection. 
 
 In the case of genitaf infection, however, as producing, say, abor- 
 tion, the infection is acquired pre-natally or at varying periods before 
 birth. To what extent resistance to disease may be effected in the 
 case of the foetus is not clear at present. 
 
 The Indirect Effect Possibly Most Important of All. — Research 
 studies have shown that a deficiency of iodine intake has a direct and 
 certain effect on the assimilation and control of such essential minerals 
 as calcium and phosphorous in the animal body, no matter how abun- 
 dantly they may be fed. Such being the case, it would seem well to 
 ensure the proper assimilation of the fundamental mineral require- 
 ments of the body by the use of, say, an iodized salt. Particularly 
 is this the case when one considers the quantity of mineral matter 
 in the milk produced by a 20,000 pound cow. 
 
 Finally, from indications with dairy cattle and from the know- 
 ledge of the general effect of potassium iodide, it would seem like wise 
 practice to utilize an iodized salt during the milking period, and 
 particularly during the period of pregnancy. The commercial variety 
 might be used regularly, or, in cases of specific trouble from goitre 
 in calves, weak calves or genital infections, a home mixed salt as 
 described for sheep might be indicated. 
 
 These general conclusions may be set forth: 
 
 1. That much remains to be learned concerning the effect of 
 
 iodine in the feeding of live stock, and in particular with 
 dairy cattle. 
 
 2. That the administration of iodine or supplementary mineral 
 
 matter to live stock will not rectify poor feeding practice or 
 
 Page Nine 
 
THE SIGNIFICANCE OF IODINE IN THE FEEDING OF LIVE STOCK 
 
 management, generally, particularly during the pregnant 
 period. It should be part of the proper hygienic methods 
 in general. 
 
 That much remains to be learned concerning quantities fed. 
 Those recommended or suggested are amply sufficient, 
 should on no account be increased in preventive treatment, 
 are apparently effective and are likely somewhat in excess. 
 The quantities mentioned in the case of a home mixed 
 iodized salt are stated, therefore, as subject to possible 
 correction. 
 
 There are in all probability other methods of obtaining the 
 results secured with iodine administration: — more intelli- 
 gent choice of feeds and the use of mineral supplements, 
 greater appreciation of such factors as winter housing and 
 management, etc., though it is obvious that where there 
 is a natural deficiency of this essential, vital element in the 
 food of stock it must be supplied to them artificially. 
 Pending the results of present and future research, how- 
 ever, the intelligent administration of iodine would now 
 seem to offer a reasonably reliable and relatively inexpensive 
 insurance as discussed in these pages. 
 
 »;=3re^=> 
 
 Page Ten 
 
Additional copies may be secured from 
 
 Canadian Co-operative Wool Growers, Limited 
 
 217 Bay Street, Toronto