Semen production and sperm motion characteristics of Bharat Merino sheep evolved in a semi-arid tropical environment

The Bharat Merino sheep has been evolved for fine wool production by crossbreeding native ewes with exotic Rambouillet/Soviet Merino rams and stabilizing the population at 75% exotic inheritance. The aim of the present study was to evaluate semen production of Bharat Merino rams maintained in a semi-arid climate and objectively assess their semen quality by the computer-aided sperm analysis technique. Semen was collected from 10 donor rams by artificial vagina on 5 occasions at alternate days at the onset of autumn breeding season. The overall means of volume (ml), mass motility (0–5 scale), sperm concentration (10⁶/ml), sperm motility (%), rapid motile (%), medium motile sperm (%), slow motile sperm (%), linearity (%), straightness (%), curvilinear velocity (μm/s), average path velocity (μm/s), straight-line velocity (μm/s), amplitude of lateral head displacement (μm), beat frequency (Hz), sperm head area (μm²) and sperm head elongation (%) were 1.04, 4.64, 3106.8, 92.2, 70.5, 14.5, 3.3, 38.0, 69.2, 232.65, 123.07, 86.12, 9.15, 24.94, 7.23 and 52.7, respectively. Although age of the ram did not influence any of the traits significantly but there was a significant effect (P<0.05) of replication on all the traits except volume, concentration and head area. However, the interaction between age and replication was not significant in any trait except on straightness. The results indicate that Bharat Merino rams are capable of producing good quality semen in a semi-arid tropical climate during autumn i.e. major breeding season and the information generated will be useful for short-term and long-term preservation of Bharat Merino ram semen.