Influence of month on some sexual beviour and semen characteristics in Holstein- Friesian bulls

Abstract

A study was undertaken to investigate the effect of month on some sexual behaviour and semen attributes in Holstein- Friesian bulls. This study was executed in the Department of Artificial Insemination, State Company of Animal Resources Services, Ministry of Agriculture Abu-Ghraib using 9 bulls of 17- 21 months of age and 350-450 kg live weight. Three hundred and eighty seven ejaculates were collected during the experimental period (43 ejaculates per bull as average). Lower (P<0.05) reaction time for ejaculate was noted during March (49.44 ± 14.86 seconds), whereas, the higher (P<0.05) reaction time was observed during September (147.6 ± 7.98 seconds). Greater (P<0.05) deep thrust was noticed in bulls during January, February and March as compared with the other months. Medium deep thrust of bulls was observed during May and June and increased obviously during September- December. Ejaculate volume was significantly lowered (P<0.05) during May- November in comparison with winter months, and increased during December. Mass activity and sperm individual motility was increased (P<0.05) during January- May and decreased (P<0.05) during June- October. Dead and abnormal sperm percentages were significantly (P<0.05) reduced during January- March and then increased to reach maximum during August and then fall during December and January. Moreover, higher (P<0.05) sperm concentration and per ejaculate were showed during January, decreased obviously (P<0.05) during May and increased (P<0.05) again throughout June- December. Semen pH did not altered during the whole experimental period and remained within the normal value. In conclusion, there are obvious changes in sexual behaviour and semen characteristics in Holstein- Friesian bulls during different months of a year in Iraq. These might take into account in future artificial insemination and breeding programs.