294EFFECTS OF LONG DAYLIGHT ON CAPRINE SCROTAL CIRCUMFERENCE AND SEMEN QUALITY
Reproduction, Fertility and Development
Seasonal variation of the reproductive activity of small ruminants in the southern USA is controlled by photoperiod. We tested the hypothesis that artificial manipulation of photoperiod has an effect on caprine testicular activity and semen quality. The objective of this study was thus to determine the effects of photoperiod on caprine scrotal circumference and semen parameters during the nonbreeding season. Ten Saanen and Alpine bucks, two to three years old, raised at the Small Ruminant
... mall Ruminant Research and Extension Center of Fort Valley State University (latitude 32°37′ N, longitude 83°39′ W), were used in the study. Throughout the study, the bucks were fed a concentrate diet containing 16% crude protein, and 2.7 Mcal/Kg of digestible energy. Two groups of bucks randomly selected were exposed to long daylight (16L:8D; n=5) or ambient daylight (12L:12D, control;; n=5) for a period of three weeks during the month of March. Scrotal circumference measurements and semen collection were conducted on each buck twice a week for a total of five trials. Semen samples were collected using an artificial vagina and an electroejaculator. Samples were immediately transferred to the laboratory for further evaluation. Data were analyzed as a completely randomized design with repeated measures using SAS program (SAS, 1990). When means were significant by ANOVA (P<0.05), they were separated by least significant difference. Results are presented as the least square means±SEM. Long daylight did not affect semen volume (mL), % motility, sperm concentration (billions/mL), % viability, or % abnormality(P>0.05). However, semen motility, sperm concentration, and abnormality were influenced by treatment in trials 3, 1, and 5, respectively (P<0.05). The least square means±SEM values for these parameters were 35±15, 0.58±0.1, and 20.0±3.7 for long daylight-treated bucks v. 87±15, 0.13±0.1, and 7.8±3.7 for the control, respectively. Further, long daylight affected scrotal circumference (P<0.05). Scrotal circumferences were decreased in trials 1, 2, and 5 (P<0.05). Long daylight decreased scrotal circumference without affecting semen quality in this study.