THE EFFECT OF FEEDING THYROID ON THE PLUMAGE 
OF THE FOWL 1 
By L. J. Cole, Chairman , Department of Genetics , University of Wisconsin , and 
D. H. Reid, Head Professor of Poultry Husbandry , Agricultural and Mechanical 
College of Texas 
The assumption of male plumage 
by the female fowl has frequently been 
observed and commented upon. When 
it occurs in nature it is usually found 
associated with a disturbance of the 
ovary (I), 2 and it may be produced 
experimentally as a sequel of ovari¬ 
otomy (8 ). The writers are not aware 
that the spontaneous assumption of 
female plumage by the male fowl has 
been reported (leaving out of considera¬ 
tion those breeds, such as the Sea- 
bright Bantam, in which it is a normal 
inherited characteristic), though it is a 
process which occurs annually in many 
dimorphically colored birds, such as 
the scarlet tanager, bobolink, and indigo 
bunting. Goodale (4, &) has suc¬ 
ceeded, however, in inducing hen¬ 
feathering in males by a combination 
of castration and implantation of 
ovarian tissue. More recently, Torrey 
and Horning ( 6 ) have reported that 
when dried thyroid was fed to normal 
growing male chicks they developed 
female plumage instead of that natural 
to their sex. No change of plumage 
was effected, however, by feeding thy¬ 
roid to normal females nor to castrated 
males or females. These results are 
of interest and seem important, even 
though a trial reported by Crew and 
Huxley (2) has failed to confirm them. 
It would seem that for the present the 
accumulation of additional evidence 
is more to be desired than extended 
discussion of the possible action of 
glandular secretions on the develop¬ 
ment and expression of secondary 
sexual characters. 
A preliminary trial of the effects of 
feeding thyroid to adult males was 
made by the writers at the Wisconsin 
Agricultural Experiment Station in the 
late winter and early spring of 1923. 
Adult males were used for the test, 
partly because no chicks were avail¬ 
able at the time and partly to see 
whether or not any effect would be 
visible in the replaced feathers of the 
grown bird. 
Ten Brown Leghorn cockerels nearly 
a year of age and one old male were used 
in the experiment. All had normal 
plumage of the breed with respect both 
to color and form of feathers. They 
were placed in individual coops (about 
the size of exhibition coops) in the 
poultry building, but were divided 
into four lots with respect to treat¬ 
ment, as follows: 
In addition to the regular ration— 
Lot 1 , consisting of four birds, re¬ 
ceived every other day at first and 
later, daily, 400 mgm. of desiccated thy¬ 
roids 3 containing 0.2 per cent iodine, 
or 0.8 mgm. iodine per dose. Torrey 
and Horning started with 50 mgm. of 
thyroids when their chicks were four 
weeks of age and increased the dose 
from time to time to 330 mgm. at the 
end of 15 weeks. They do not state 
the weights of their birds, but the 
writers have assumed that these 
weighed about 4 pounds when 19 
weeks of age, and the dose for the 
birds in the present experiment, which 
averaged about 4.75 pounds, was 
calculated at approximately the same 
proportion in relation to weight. The 
material was easily administered in 
capsules. 
Lot 2, two birds, each fed 1.05 
mgm. KI, in capsules, the iodine con¬ 
tent being equivalent to that in the 
thyroids. These were fed at the same 
intervals as the thyroids. 
Lot 3, two birds, each given at the 
same periods by pipette 1 cc. of 0.08 
per cent solution of iodine in 28.5 per 
cent alcohol. 
Lot 4, three birds, controls, received 
no dosage. 
The experiment was begun on Febru¬ 
ary 9, all birds being given their doses 
on succeeding alternate days up to 
March 1; after that they were dosed 
daily until the experiment was con- 
1 Received for publication Apr. 8, 1924. Issued January, 1925. Paper No. 42, from the Departments of 
Genetics and Poultry Husbandry, Wisconsin Agricultural Experiment Station. Published with the 
approval of the Director. 
2 Reference is made by number (italic) to “Literature cited,” p. 287. 
3 The writers desire to express their appreciation to Armour & Co., Chicago, for their kindness in furnish¬ 
ing the thyroids used in this experiment. 
Journal of Agricultural Research, 
Washington, D. C. 
( 285 ) 
Vol. XXIX, No. 6 
Sept. 15, 1924 
Key No. Wis.-26 
