THE CHICK COMB FOR ANDROGEN ASSAY1

Abstract

A study was made of 1318 White Leghorn chicks given testosterone-propionate or testosterone in dosages ranging from 1 to 1000 [gamma]. Cockerels and pullets on a limited diet gave significant responses to subcut. inj. but normal diet cockerels had smaller combs than the controls at dosage levels of 25-50 [gamma]. Adm. of 100 [gamma], however, produced significant growth. This variation was apparently the result of a decreased testicular androgen secretion which at low dosages more than offset the effect of the injected androgen. Limited diet birds, in contrast, responded essentially as castrates; the problem of endogenous secretion was therefore eliminated. Injs. of androgen into the comb were very efficacious especially when administered on alternate days. A total of 2.5 [gamma] produced a comb increase of more than 32%. Chicks caponized at 5 days given comb injs. on alternate days had comb increments of more than 31% at 20 days of age after adm. of only 1 [gamma]. Normal diet pullets similarly treated although somewhat less responsive also gave significant increases with as little as one [gamma] of testo-sterone-propionate. In a short assay method birds were injected at 12 hrs. after hatching and autopsied at 80 hrs. and gave positive responses to amts. of hormone ranging from 25-200 [gamma].