3
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 1928.)
INTRODUCTION.
IT has been shown by Marine and Williams (1908) and Kendall (1914) that iodine may be regarded as the active constituent in thyroid secretion. Thus it is that the relative activity of the thyroid may be assessed by measurement of its iodine content. It is established that the iodine content of the thyroids varies with the diet (Baumann, 1896), general health (Marine and Lenhart, 1922), and season (Riddle and Fisher, 1925; Seidell and Fenger, 1912-13), and that in addition there are individual differences. Riddle and Fisher record further that in the pigeon the size of the thyroid increases with advancing age but found no evidence of sex dimorphism in thyroid size in that particular form.
MATERIAL.
The thyroids of healthy, freshly killed fowls and mammals were used. The glands were carefully and completely removed, freed from all adventitious tissues and thoroughly desiccated over concentrated H2SO4. When perfectly dry the
tissue was accurately weighed. In the case of the fowl the complete thyroid tissue of each individual was used, but in the case of the larger mammals only a portion of recorded weight of the desiccated 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 con-ditions 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 thyroids of certain animals, as estimated by previous workers on this subject, is shown in Table I.
Table I.
Species Man Dog Sheep Cattle Pig PigeonPercentage of iodine of desiccated thyroids Maximum 0-588 «-358 0-265 0-283 Minimum 0-051 0-131 o-on 0-032 Average O'349 O-22O 0-332 0-095 0-166 0-246 0-346 0-251 0-485 Authority Seidell Seidell
Marine and Lenhart Cameron
Seidell
Marine and Lenhart Marine and Lenhart Marine and Lenhart Cameron
367
1. 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. I t was found that spermatogenesis was active and complete at 14 weeks.
Table I I .
No. of bird 1 2 3 4 5 6 7 8 9 10 11 12 Age in weeks when killed
1
8 9 9* 10 12 13* 14 I 4i14I 15 Body weight in gm. 35O 448
sTs
420 672 1036 770 840 1092 980 Weight of desiccated thyroid in gm. 0-007 0-007 0-007 0-006 0-007 0-004 o-oio O-OI2 o-oio 0-015 0-013 0-014 Total iodine inmg. 0-0140 0-0306 O-O2OI 0-0227 0-0254 0-0140 0-0422 0-0315 0-0520 0-0780 0-0736 0-0672 Percentage of iodine ofdesiccated thyroid 0-200 O-437 0-287 0-379 0-363 0-350 0-422 0-262 0-520 0-520 0-566 0-480
It is seen that at 14 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 (1908) record a low iodine content in individuals under 6 months of age.
368
A. C. CHAUDHURI2. THE IODINE CONTENT AND SEX.
Fenger (1912-13), in the case of cattle foetuses, found that the iodine content of the female thyroid was higher than that of the male, and suggested, therefore, that the female thyroid 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, 14 adult and related bantams (Old English Game) were examined.
Table I I I .
No.
1 2 3 4 5 6 7
Average
1 2 3 4 5 6 7
Average
Sex
6* 6*
S 6 S
6* 6*
6*
2 $ $ 0 Q $ O -r*
$
Weight of desiccated thyroid
in gin.
0-009 0-020 0-012 0-009 O-OI2
o-oio
O-OI2
o-oio
O-OI2 O-OI2
o-oio
O-OI-2 O-OI5
o-oio
Total iodine in mg.
0-0405
0-2200
0-0680 0-0585 0-0748 0-0583 0-0669
0-0360 0-0990 0-0770 0-0496 0-0637 0-0863 0-0520
Percentage of iodine of the desiccated
thyroid
0-450
I-IOO
0-566 0-650 0 6 2 3 0-583 O-557
0-647 ±0*049
0-360 0-825 0-641 0-496 0-530 O-575 0-520
0-563 ±0-033
The difference between the average iodine contents of males and females is 0-084 ±0-058, i.e. 1-4 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 thyroid exists.
3. 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 0-482 ± 0-045, 2-e- 10'7 times its own probable error, and therefore statistically
significant.
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.
N o .
18 2 4
2 0
2 7
2 1 2 2
2 3
2 5 2 6
4 5
6
1 0 1 9
Animal
Dog Dog Goat Goat Rabbit Rabbit Rabbit
Duck Duck Fowl Fowl Fowl Fowl Fowl
Weight of desiccated thyroid
in gin.
0-200 0-205
(o-ioo)*
0-240 0-065 0-054 0*029
O-O2O O-O3O
O-O35 0-045
0-060 0-030
O-O2O
Total iodine inmg.
0-4928 0-9600 (0-1870)
0-6210 0-0340 0-0930 0-0350
0-1240 0-3310 0-4128 0-4704
0-4896
0-2113
0*1386 Average of 14 bantam fowls (from Table III)
Percentage of iodine in
desiccated thyroid 0-246) 0-468/
0-187! 0-258/ 0-052 j O-I73 r 0-123)
0-6211 1-104/
1-179,, I-O45
0-816 V
0*704 0-693-/
Average percentage
of iodine of the species O'357
0-222
0-116
0-862
0-887
0-605
Average per-centage of iodine
of the group
0-215 ±0-031
(Mammals)
0-697 ±0-033 (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.
1. The iodine content of the thyroid of the sexually immature male fowl is lower than that of the thyroid 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.
2. In the case of the material used there was no indication of a sex dimorphism in the matter of iodine content.
3. The average percentage of iodine content of the thyroid of the bird is significantly higher than that of the mammal.
REFERENCES.
BAUMANN, E. (1895-1896). "Ueber das normale Vorkommen von Jod im Thierkorper." Zeit.f.
phys. Chem. 21, 319-330.
(1896-1897). "Ueber den Jodgehalt der Schilddriisen von Menschen und Thieren." Zeit.
f. phys. Chem. 22, 1-17.
CAMERON, A. T . (1913). " Note on the iodine content of fish thyroids." Biochem.Journ. 7,466-470,
(1913-1914). " T h e iodine content of the thyroid and some branchial cleft organs." Journ.
Biol. Chem. 16, 465-473.
FENGER, F . (19I2). " O n the presence of active principles in the thyroids and suprarenal glands
before and after birth." Journ. Biol. Chem. 11, 489-492, also 12, 55-60.
370 A. C. CHAUDHURI
HUNTER, A. (igio). " T h e determination of small quantities of iodine, with special reference to the iodine content of the thyroid gland." Journ. Biol. Chem. 7, 321—349.
KENDALL, E. C. (1914). " The determination of iodine in connection with studies in thyroid activity."
Journ. Biol. Chem. 19, 251-256.
MARINE, D . and LENHART, C. H. (1922). "Further observations on the relation of iodine to the
structure of the thyroid gland in the sheep, dog, hog, and ox." Arch. Int. Med. 3, 66-77.
MARINE, D . and WILLIAMS, W. W. (1908). " T h e relation of iodine to the structure of the thyroid gland." Arch. Int. Med. 1, 349-384.
RIDDLE, O. (1925). "Reciprocal size changes of gonads and thyroids in relation to season and
ovulation. Note on pigeon." Amer. Journ. Phys. 73, No. 1, 5-16.
RIDDLE and FISHER, W. S. (1925). "Seasonal variation of thyroid size in pigeons." Amer. Journ.
Phys. 72, No. 3, 464-487.
SEIDELL, A. (1911-1912). "Further experiments upon the determination of iodine in thyroid."
Journ. Biol. Chem. 10, 95-108.
SEIDELL and FENGER, F. (1912-1913). "Seasonal variation in the iodine content of the thyroid
