Effect of Restricted Daylength During the Growing Period on Semen Quality and Fertility of Turkey Toms

Two trials were conducted in which three daylength and light intensity treatments were applied to 144 growing turkey toms from 8 to 28 weeks of age. Treatments were (1) six hours of artificial light, (2) natural light and daylength, and (3) simulated natural daylength. At 28 weeks of age all toms were placed on 14 hours of daily light. Individual tom semen quality was evaluated every two weeks for six months, and on alternate weeks, eight hens were inseminated with semen pooled by treatment replicate to obtain fertility (May to December). Seasonal decline in semen production, sperm concentration, semen volume, and fertility was observed for toms on natural daylength after three months of production. Toms on six hours of light and those on simulated natural light maintained high levels of production and quality for the entire six month period. Semen production expressed as the average number of toms producing semen, sperm concentration, and fertily were significantly lower (P less than .01), and semen volume was significantly lower (P less than .05) for toms on natural light after six months. It was concluded that natural light was less desirable than controlled light for "off season" growing of toms.