Spermiogram of Low vis á vis High Sperm Output Crossbred Frieswal Bulls

Abstract

Project Directorate on Cattle (Indian Council of Agricultural Research), Meerut Cantt (UP) Frieswal crossbred bulls (n=80) of 15-30 months age were categorized into 3 groups based on sperm output potential. The objectives of the study were to assess comparative spermiogram and suggest suitable bull selection criteria based on sperm productivity indices. Each bull of group 1 had average sperm output one standard deviation (SD) below the mean (<μ-1 SD i.e. <522 million / ml), group 2 within the range μ±1 SD (i.e. 522-1310 million / ml) and group 3 very high potential bulls (>μ+1 SD i.e. >1310 million/ml). Ejaculate volume did not differ significantly among 3 groups. Group 1 bulls had significantly (P<0.01) lower sperm progressive motility, viability and 2-3 folds higher abnormal sperms as compared to groups 2 and 3 bulls. All the bulls in group 1 had more than 40 % sperm abnormality (range: 44.2 to 87.25%). Abnormal spermiogram in these bulls includes detached head (22.06%), proximal protoplasmic droplets (9.03%), tail looped over head (4.05%), 'Dag' like defect (3.57%), pyriform head (3.16%), looped mid piece (2.94%) and many others. A sizable proportion of groups 2 & 3 bulls also showed higher degrees of sperm defects. Group 2 bulls had significantly higher sperm abnormality (28.96±1.50%) than that of group 3 (18.33±2.12%). In group 1, not a single bull produced semen of acceptable post thaw motility suitable for AI. It was concluded that less sperm output was not merely inferior rate of spermatogenesis, but signified wide spectrum of sperm morphological defects. Young crossbred bulls with sperm output below 500 million /ml did not yield freezable quality semen and thus recommended for earliest culling. In Frieswal crossbred bulls having very high levels of sperm productivity do not always ensures semen of high quality, freezability and normal sperm morphology. Preferential selection of young bulls having sperm output potency one SD higher than mean (>1300 million/ml) can ensure more number of freezable quality semen producer (AI sire) bulls.