On the Measurement and Inheritance of Sexual Maturity in Turkeys (Meleagris gallopavo)

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Abstract
An analysis of the trapnest records of turkeys for a period of 7 yrs. showed date of 1st egg to be a better measure of sexual maturity in this species than age at 1st egg. Time of hatch, within the usual hatching period of about 2 months, had little influence on date at 1st egg; whereas the later hatched birds started to lay at an earlier age. Two lines that differed significantly in date of 1st egg were established by selection. Reciprocal crosses were made between the 2 lines. The progeny of early [male] X late [female] started laying earlier than the progeny of late [male] X early [female] but at the same time or later than the [female][female] in the early maturing line. The [female][female] in the late maturing line started laying at a later date than the progeny of late [male] X early [female]. The data for these selected lines and the progeny of reciprocal matings between them show that sexual maturity in turkeys is determined by both sex-linked and autosomal genes. On the basis of differences in the weights (and ages) of chickens and turkeys at the time they start to lay, as compared with their maximum lst-yr. weight, it is suggested that physical maturity is a less important factor in determining the onset of egg production in turkeys than in chickens and that turkeys have a higher threshold of response to environmental stimuli than do chickens.