Effect of Light Environment During the Adolescent Period on Subsequent Semen Volume and Concentration of Male Turkeys

Abstract

One hundred eighty males were utilized in two field-type experiments. In one experiment, light was restricted to 6 or 12 hr of light per day at a light intensity of 10.76 lx from 12 through 28 weeks of age. In the second experiment, one flock was maintained under natural light while the other was maintained under 12-hr lights and 10.76 lx of light intensity from 12 to 31 weeks of age. All flocks were placed under a 14-hr light day and alight intensity of 32.3 lx in light-controlled houses during the breeding season.Results obtained in the first experiment showed an increase in semen volume from the first to the fourth observation period and then a decline in both flocks during the last period. Average semen volume over the entire experimental period was unaffected by light treatment during the adolescent period. Semen concentration was highest during the early part of the breeding season and gradually declined as the season progressed. Males under a 6-hr restricted light regimen during the rearing period produced an average of .6 billion more sperm cells per milliliter than did those reared under 12 hr of light per day (P≤.01).Results obtained in the second experiment showed an average semen volume throughout the breeding season of .24 and .19 ml and a semen concentration of 7.0 and 6.4 billion sperm cells per milliliter for males reared under natural light compared to those reared under 12-hr lights, respectively. These differences were significant (P≤.01).Data were subjected to polynomial analyses. Semen concentration over the breeding season showed a significant quadratic trend on semen volume in all flocks. The low R2 values obtained suggested that semen volume may not be a useful measure for predicting semen concentration.