Change in the effect of constant photoperiods on the rate of sexual maturation in modern genotypes of domestic pullet

Lewis, P. D. and Morris, T. R. (2005) Change in the effect of constant photoperiods on the rate of sexual maturation in modern genotypes of domestic pullet. British Poultry Science, 46 (5). pp. 584-586. ISSN 0007-1668 doi: 10.1080/00071660500255141

Abstract/Summary

1. Data for modern egg-type hybrids reared on constant daylengths show that, as expected, they mature more quickly than earlier genotypes. However, the constant photoperiod which gives earliest sexual maturity has not changed as a result of selection and is 10 h for both early and modern genotypes. 2. Further analysis showed that the rate of delay in sexual maturity for constant photoperiods above 10 h is similar for modern and for early hybrids ( +0.29 d for each incremental one hour of photoperiod), the response of modern hybrids below 10 h ( +4.22 d for each one-hour reduction in photoperiod) is more than double that of early hybrids ( +1.71 d/h).