Observations on the Low Fertility Problem in Cornish Cockerels

DURING the course of some investigations on the effect of male to female ratios on fertility in flock matings of chickens, it was observe d that when Dar k Cornish cockerels were mated to New Hampshire pullets, fertility appeared to be lower than when either Delaware or New Hampshire cockerels were used (Parker, 1958a). Increasing the relative numbers of Cornish males in the flocks from four to as many as eleven per 100 females did not increase fertility. The purposes of the following investigations were to compare the fertilizing capacity of Dark Cornish males with that of New Hampshire, Delaware, and Cornish × New Hampshire crossbred males in controlled experiments and to attempt to determine the factor or factors contributing to the differences in fertility. FERTILITY IN FLOCK MATINGS To compare the fertilizing capacity of Cornish cockerels with that of New Hampshire and Delaware cockerels three pens of approximately 100…