Hen-feathering induced in the male fowl by feeding thyroid

Abstract

It is already well known to the members of this Society that the males of certain breed of fowls—notably Sebright bantams and Campines—are feathered so like the females as to be in this respect practically indistinguishable from them; and that such hen-feathered males, following castration (especially in early life), develop plumage of the usual male type. This appearance of cock-feathering in normally hen-feathered males after castration is now familiar to us. It is the purpose of this paper to call attention to experiments that have led to a similar transformation but in just the opposite direction, namely, to the appearance of hen-feathering in cock-feathered males of ordinary breeds. We had begun a series of preliminary experiments upon the physiological correlations of certain of the ductless glands. Eighty Rhode Island Red chicks were under observation. They were of the same hatch. They had been divided into four lots of twenty each. All the birds in two of the lots, both males and females, had been castrated between two and four weeks after hatching. Those in the other two lots were unaltered. Four weeks after hatching, one lot of castrated birds and one lot of normal birds had begun to receive daily doses of dried thyroid (Armour and Company, containing 0.2 per cent. I) by mouth. The initial individual dose was 50 mg. It was increased from time to time. At the end of fifteen weeks it had become 330 mg.- a dose the birds were able to take without any disturbance of their normal health. There is a striking difference between the sexes of this breed of fowls with regard to the time at which the tail coverts make their appearance. These feathers began to show themselves in some of our birds six weeks after hatching.