Investigation on the correlation of testicular size with semen production parameters in crossbred (Friesian X Sahiwal) bulls

The present study was planned to investigate the correlation of the testicular size with semen production parameters in crossbred (Friesian x Sahiwal) bulls. A total of 12 adult Friesian x Sahiwal crossbred bulls with clinically normal reproductive tract maintained at the Semen Production Unit, AI-Haiwan Sires, Pakpattan Road, District Sahiwal were used. These bulls were divided into three age groups; group I (2-3 years of age), group II (4-6 years of age) and group III (7-10 years of age). Scrotal circumference of these bulls was measured by bringing the testis into the distill part of the scrotum until the ventral scrotal folds, if any, were eliminated and then testicular size was measured by the measuring tape. Two ejaculates per animal were collected twice a week with the help of artificial vagina. A total of 60 ejaculates were collected from the selected bulls. Each semen sample was evaluated for volume, mass activity, color, pH, percent motility of sperm, sperm concentration per ml, percent of live sperm and percent of morphologically abnormal sperm. The data was subjected to the statistical analysis by using completely randomized design and analysis of variance. The effect of age on scrotal circumference, testicular length, testicular diameter (right) and testicular diameter (left) of the bulls of present study was highly significant (P less than 0.01). Similarly, the effect of age on semen volume was observed to be significant (P less than 0.05). However, there was a non-significant (P greater than 0.05) effect of age on semen pH, sperm motility percentage, sperm concentration/ml, live sperm percentage, morphologically abnormal sperm percentage and mass activity. The correlation of age was positive for all testicular measurements and semen volume while there was no effect of age on semen pH, sperm motility percentage, sperm concentration/ml and mass activity in bulls of the present study.