Demonstration of the effects of castration on Seabright cockerels

Abstract

Two years ago I demonstrated before this Society castrated F₁ and F₂ cockerels that had been hen-feathered, but which in consequence of the operation had, after moulting, begun to produce feathers characteristic of the normal male. Those birds have been kept to the present time, and now show a complete change to the cock-feathered type, except that the comb is reduced in size as in the ordinary capon. The spurs, however, appear to have their full growth. Since the F₁ birds were certainly heterozygous, and the few F₂ birds operated upon might have been heterozygous for cock feathering, it became desirable to carry out the operation on the pure Seabright cockerels which are always hen-feathered. The change in them, as the birds before you show, is as marked and as complete as in the F₁ and F₂ birds.

One bird after completely changing to cock-feathering (with reduced comb also) began after six months to change back; and, as is demonstrated by the bird, is at present in an intermediate stage. The comb has begun to enlarge again. Presumably a small piece of the testis was left—not large enough at first to prevent the change to cock-feathering—which has regenerated so far, that, at the last moult, the new feathers were affected.