Abstract
This is a preliminary report on the broodiness in F1 chicks derived from various crosses between cocks and hens of the Plymouth Rock fowl. Broodiness in the cocks was determined by their reaction to Prolactin injections; that of the hens by the usual trap-nest method. The chicks were hatched in May, 1951, and twelve of the pullets began to lay that autumn. Observations made from then until the autumn of 1952 gave the following results;
1. Four F1 females from the cross between a non-broody cock and a non-broody hen showed no broodiness.
2. Two F1 females from the cross between a non-broody cock and a slightly broody hen showed no broodiness.
3. In three F1 females from the cross between the same non-broody cock and a strongly broody hen, one showed broodiness, two did not.
4. Three F1 females from the cross between a broody cock and a broody hen all showed broodiness.
These results seem to indicate that the effect of Prolactin injections parallels the genic constitution of the cocks in regard to broodiness, and that Prolactin may be of use in eliminating broodiness from the strains of domestic fowl.
