ABSTRACT
The objective of present study was to investigate the effect of endogenous minerals (Zn and Ca), seminal proteins and oxidative stress on semen quality of crossbred bulls. Two crossbred bulls with history of good initial quality, high sperm motility percentage, and freezable ejaculates and poor initial quality, low sperm motility percentage, and donating mostly non-freezable ejaculates (Bull B), respectively were utilized. Six ejaculates from each bull were used and categorized into high progressive motile as good quality and low progressive motile as poor quality ejaculates groups. Total 24 ejaculates were taken during entire period of study. The level of Zn, Ca in seminal plasma and Ca in sperm pellets was found significantly (P<0.05) higher in good quality ejaculates of Bull A compared to poor quality ejaculates of Bull B; however, the level of reactive oxygen species and malondialdehyde was significantly higher (P<0.05) in poor quality ejaculates of Bull B compare to good quality ejaculate of Bull A. The 25 kDa protein band was prominent only in good quality ejaculate of Bull A. It was concluded that several proteinaceous antioxidant enzymes which may be present in 25 kDa band and minerals like Zn and Ca as a cofactors of these enzymes could be responsible for good quality semen ejaculates of Bull A