The effect of season on the scrotal circumference and sperm motility and morphology in rams.

Seasonal variations in scrotal circumference, sperm motility, morphology, and body weight were studied in ten Suffolk and ten Lincoln yearling rams. There were marked seasonal variations in the scrotal circumference and sperm morphology for each of the breed types. Mean scrotal circumferences were highest in October, 36 cm and 37 cm for Suffolk and Lincoln, respectively. Sperms which were morphologically normal were highest in October, 92.8% for both breeds, and lowest in February, 56.1% and 58.8% for Suffolk and Lincoln, respectively. There was a subsequent rise in percent of normal sperm which was seen in April with a decline again during the summer months. Mean body weight was 251.5 and 192.5 pounds in October and 250.77 and 200.63 pounds in February for Suffolk and Lincolns, respectively.