Effect of Supplying Extra Light on Semen Production of Male Chickens

Abstract

Two tests were consecutively conducted using spring-hatched White Leghorn males to examine if semen production could be improved by keeping male chickens under long daylength throughout the year.
In the first test, 24 males reared in natural daylight were divided into two groups; one received an increasing daylength for the first 8 weeks and then 14 to 15 hours of daily light to the end of the test, the other received natural daylight alone. The test began in November 1966 and ran for 56 weeks. Semen samples were examined weekly for the semen characteristics, and fertilizing capacity was determined monthly by artificial insemination.
In the second test, each half of the males of the groups used in the first test were exchanged between the previous treatments, and one group received 15 hours of light, the other received natural daylight alone. The semen characteristics were examined for 20 weeks from December 1967 to April 1968.
The results were as follows:
1. Males supplied with extra light showed an improvement in semen characteristics and fertility, and seasonal decline was reduced. Adverse effect of supplementary light was not observed.
2. Semen production during the cold season seemed to be much affected by daylength, but not by ambiant temperature.
3. Correlations between fertility and semen characteristics were comparatively low in the males supplied with extra light.
4. It is suggested that control of photoperiod length with artificial light is effective on semen production, and that semen production in its declining season can be improved by keeping male chickens on a 14 or 15 photoperiod.