FACTORS AFFECTING BULL SEMEN QUALITY AT BREEDING STATION

Abstract

The knowledge of factors affecting sperm production and semen quality is important with regard to reproductive efficiency and thus genetic improvement, hence, this study aimed to investigate the effects of breed, age, scrotal circumference, BCS, season and nutrition on bull semen quality at breeding bull station of Ejab Alliance Limited, Thakurgaon, Bangladesh. A total of 777 ejaculates were collected from 25 bulls (Friesian=10; Sahiwal=15) using an artificial vagina. Ejaculate volume, concentration, mass activity, individual motility, morphology significantly (P<0.05) differed with the factors. All semen parameters were significantly (P<0.05) higher in Sahiwal bulls than in Friesian bulls except concentration which vary non-significantly (P>0.05) between the two breeds. No significant (P>0.05) effects of breed, age, BCS and nutrition were found on the concentration of semen. The volume, individual motility, mass activity and sperm morphology were significantly (P<0.05) higher in adult age group (>3.5-4.5 years) than in younger (2.5-3.5 years) and older groups (>4.5years-above). Scrotal circumference significantly (P<0.05) affected all the parameters regarding to semen quality. The highest values were observed in bulls with scrotal circumference of 31.1-33 cm and the lowest values were observed in bulls with scrotal circumference of 33.1 cm to above. The volume, individual motility, mass activity and sperm morphology were higher (P<0.05) in bull group with BCS of 4 to 4.5 than in bull group with BCS of >4.5 to 5. Significantly (P<0.05) highest values regarding to semen quality were found in winter and the lowest in summer but the effect of season on volume was non-significant (P>0.05). During the study, Vit. ADE supplementation significantly (P<0.05) improved the semen quality. In conclusion, Sahiwal breeds should be promoted at the bull station in the subtropical condition like Bangladesh. Most semen should be collected during winter. Bulls of >3.5 to 4.5 years of age with moderate scrotal circumference and BCS should be the choice of priority. This conclusion, however, is based only on one year study, a long duration trial need to be necessary to confirm the effects of all related factors and their interactions with the reproductive physiology and management of bulls in a breeding station.