This study was conducted among 120 different breed cows at selected areas of Sirajgonj district from March to July 2010 to compare the reproductive performance of crossbred and Desi cows at farmer’s level. The results showed that the average daily milk yield of Desi, Shahiwal × Desi, Friesian × Desi and Jersey × Desi cows was 2.3 ± 0.2, 4.9 ± 0.9, 6.0 ± 1.0 and 5.7 ± 0.9 liters, respectively. The milk yield of crossbred cows (5.5 ± 0.6 liters/day) was significantly (p<0.01) higher than Desi cows (2.3 ± 0.2 liters/day). The average age at puberty of Shahiwal × Desi, Friesian × Desi and Jersey × Desi was significantly (p<0.01) lower than that of Desi breed. The crossbred cows had significantly (p<0.01) lower pubertal age (20.4 ± 1.2) than Desi (25.9 ± 1.1). The age at first calving in Desi cows was significantly (p<0.01) higher (37.6 ± 1.1 months) than crossbred cows (31.2 ± 1.3 months). The average gestation length of Desi, Shahiwal × Desi, Friesian × Desi and Jersey × Desi was 289.9 ± 1.4, 285.0 ± 0.0, 285.0 ± 4.2 and 282.1 ± 2.4 days, respectively. It is suggested that the overall reproductive performance of Friesian × Desi, Jersey × Desi and Shahiwal × Desi cows were better than that of Desi cow.

Alpha-tocopherol as an antioxidant acts in preservation of chilled semen by preserving cell membrane damage from lipid peroxidation. Optimum concentrations of α-tocopherol in egg yolk-citrate (EYC) extender need to be studied in crossbred bull’s semen. Different concentrations of α-tocopherol viz. 0, 1, 2, 4 and 6mg per ml of extender were used. Semen was collected once a week from four bulls used to regular collection, aged 4 to 7 years, weighing 320 to 450 kg, and with body condition score 4 to 4.5 and scrotal circumference 23 to 32 cm. Semen was evaluated routinely and sperm morphology was viewed under light microscope at ×1,000 magnification after fixing with buffered formal saline. Over 90% had normal head, acrosome, mid-piece and tail. Semen was diluted with egg-yolk-citrate extender to produce 15×106 spermatozoa/ml and 0, 1, 2, 4 and 6 mg/ml α-tocopherol were added. The semens amples were kept at 8℃. Sperm motility and viability were examined daily up to 5 days under light microscopy at ×200 magnification. Sperm viability was acceptable (≥40%) up to the 4th day with all concentrations of α-tocopherol and up to the 5th day with 2 mg/ml α-tocopherol. Sperm motility was acceptable (≥40%) up to the 3rd day irrespective of α-tocopherol concentration, and up to the 4th day with 2 mg/ml α-tocopherol. It is suggested that the lifespan of chilled semen may be extended up to 4 days by adding 2mg/ml α-tocopherol.