THE IODINE CONTENT OF THE THYROID OF THE FOWL WITH REFERENCE TO AGE AND SEX

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1 66 THE IODINE CONTENT OF THE THYROID OF THE FOWL WITH REFERENCE TO AGE AND SEX BY A. C. CHAUDHURI, B.SC. (AGRIC). Animal Breeding Research Department, University of Edinburgh. {Received ist January 98.) INTRODUCTION. IT has been shown by Marine and Williams (908) and Kendall (9) that iodine may be regarded as the active constituent in secretion. Thus it is that the relative activity of the may be assessed by measurement of its iodine content. It is established that the iodine content of the s varies with the diet (Baumann, 896), general health (, 9), and season (Riddle and Fisher, 95; and Fenger, 9-), and that in addition there are individual differences. Riddle and Fisher record further that in the pigeon the size of the increases with advancing age but found no evidence of sex dimorphism in size in that particular form. MATERIAL. The s of healthy, freshly killed fowls and mammals were used. The glands were carefully and completely removed, freed from all adventitious tissues and thoroughly over concentrated H SO. When perfectly dry the tissue was accurately weighed. In the case of the fowl the complete tissue of each individual was used, but in the case of the larger mammals only a portion of recorded weight of the gland was taken. Kendall's method for the estimation of iodine was employed. In order to obviate seasonal variation the work was completed during the spring. The fowls had been kept under identical conditions and fed on the same rations oats, maize, middlings, and bran. They were at liberty on grass. The goats were grazing. The rabbits had been fed on hay, cabbage, oats and flaked maize. The iodine content of the s of certain animals, as estimated by previous workers on this subject, is shown in Table I. It is noticed that among these figures there is considerable disparity. Some is doubtless due to errors and differences in methods of investigation. Much, no doubt, is the reflection of the facts that the iodine content is an indication of the relative functional condition of the and that the activity of the varies with the season, with the phases of the reproductive cycle, with health, with diet, and so forth. It is seen that in the list the iodine content of the of the bird is greater than in the case of the mammal.

2 The Iodine Content of the Thyroid of the Table I. 67 Species Maximum Percentage of iodine of s Minimum Authority Man Sheep Cattle Pig Pigeon « o-on 0-0 O'9 O-O Cameron Cameron. THE IODINE CONTENT OF SEXUALLY IMMATURE AND MATURE FOWLS. Twelve White Wyandotte cockerels from the same parental pen, of the same age, and all kept under identical conditions, were used. The onset of sexual maturity was determined by histological examination of the testes. It was found that spermatogenesis was active and complete at weeks. No. of bird Age in weeks when killed 8 9 9* 0 * I i I 5 Body weight in gm. 5O 8 sts Table II. in gm inmg O-OOI Percentage of iodine of 0-00 O It is seen that at weeks, that is, at the time of sexual maturity, in this stock, the iodine content becomes higher. The suggestion which emerges from these figures is that the iodine content is higher in the sexually mature bird, the increase being associated with the establishment of active spermatogenesis. In the case of the dog, Marine and Williams (908) record a low iodine content in individuals under 6 months of age. According to Riddle (95) the seasons (autumn and winter) of increase in the size of the are the seasons of diminution in the size of the gonads. He does not maintain, however, that variations in the size of are paralleled with variations in iodine content.

3 68 A. C. CHAUDHURI. THE IODINE CONTENT AND SEX. Fenger (9-), in the case of cattle foetuses, found that the iodine content of the female was higher than that of the male, and suggested, therefore, that the female was functionally more active than that of the male foetus of the same age. In order to examine this question of a possible sex dimorphism of this kind in the fowl, adult and related bantams (Old English Game) were examined. Table III. No. Sex in gin. in mg. Percentage of iodine of the 56 7 S 6S I-IOO O ±0* Q O -r* O-OI- O-OI O ±0-0 The difference between the average iodine contents of males and females is 0-08 ±0-058, i.e. - times its own probable error, and therefore statistically negligible. These figures afford no evidence that in the case of these fowls a sex dimorphism in the matter of iodine content of the exists.. THE IODINE CONTENT OF THE THYROIDS OF MAMMALS AND BIRDS COMPARED. In order to examine anew the suggestion which appeared in Table I, that the iodine content of the bird was higher than that of the mammal, I made use of whatever mammalian material became available, and the result of the examination of these specimens is given in Table IV. The difference between the average iodine contents of birds and mammals is 0-8 ± 0-05, - e - 0 '7 times its own probable error, and therefore statistically significant. From these figures it would appear to be the case that the iodine content of the of the bird is indeed higher than that of the of the mammal. It did

4 The Iodine Content of the Thyroid of the 69 not seem reasonable to ascribe any significant part of this difference to differences in reproductive activity, in food, or in general health, and all were adult individuals. Table IV. No. Animal in gin. inmg. Percentage of iodine in percentage of iodine of the species percentage of iodine of the group Goat Goat Duck Duck (o-ioo)* * (0-870) O-OO O-OO O-O O-OO 0*86 of bantam fowls (from Table III) 0-6) 0-68/ 0-87! 0-58/ 0-05 j O-I7 r 0-) / -79,, I-O V 0* / O' ±0-0 (Mammals) ±0-0 (Birds) * Amount taken. I wish to express my thanks to Dr F. A. E. Crew, who called my attention to the possible interest of this study, for his help during its course. SUMMARY.. The iodine content of the of the sexually immature male fowl is lower than that of the of the sexually mature. The increase in iodine content is coincident with the attainment of sexual maturity as estimated by the histological picture of the testis.. In the case of the material used there was no indication of a sex dimorphism in the matter of iodine content.. The average percentage of iodine content of the of the bird is significantly higher than that of the mammal. REFERENCES. BAUMANN, E. ( ). "Ueber das normale Vorkommen von Jod im Thierkorper." Zeit.f. phys. Chem., 9-0. ( ). "Ueber den Jodgehalt der Schilddriisen von Menschen und Thieren." Zeit. f. phys. Chem., -7. CAMERON, A. T. (9). " Note on the iodine content offish s." Biochem.Journ. 7,66-70, (9-9). "The iodine content of the and some branchial cleft organs." Journ. Biol. Chem. 6, FENGER, F. (9I). "On the presence of active principles in the s and suprarenal glands before and after birth." Journ. Biol. Chem., 89-9, also, (9). "On the iodine and phosphorus content, size, and physiological activity of the fetal gland." Journ. Biol. Chem.,

5 70 A. C. CHAUDHURI HUNTER, A. (igio). "The determination of small quantities of iodine, with special reference to the iodine content of the gland." Journ. Biol. Chem. 7, 9. KENDALL, E. C. (9). " The determination of iodine in connection with studies in activity." Journ. Biol. Chem. 9, MARINE, D. and LENHART, C. H. (9). "Further observations on the relation of iodine to the structure of the gland in the sheep, dog, hog, and ox." Arch. Int. Med., MARINE, D. and WILLIAMS, W. W. (908). "The relation of iodine to the structure of the gland." Arch. Int. Med., 9-8. RIDDLE, O. (95). "Reciprocal size changes of gonads and s in relation to season and ovulation. Note on pigeon." Amer. Journ. Phys. 7, No., 5-6. RIDDLE and FISHER, W. S. (95). "Seasonal variation of size in pigeons." Amer. Journ. Phys. 7, No., SEIDELL, A. (9-9). "Further experiments upon the determination of iodine in." Journ. Biol. Chem. 0, SEIDELL and FENGER, F. (9-9). "Seasonal variation in the iodine content of the gland." Journ. Biol. Chem.,