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The study was conducted to determine the quality characteristics of fresh and post-thaw semen of Holstein Friesian bull, maintained at Semen Production Unit, Quetta Baluchistan, Pakistan. The semen were evaluated for volume, pH, mass activity, sperm concentration, sperm motility and integrity of sperm cell membrane. The semen qualifying these criteria were processed for freezing. The frozen semen after thawing was assessed for progressive linear motility and intact cell membrane. The mean ejaculate volume of semen was recorded as 6.93, 6.59 and 6.61 ml, pH; 6.58, 6.59 and 6.61, mass activity of sperms 3.87, 3.75 and 3.5 and sperm concentration 1349.12x106, 1509.37x106 and 1364.37x106 /ml during the month of May, June and July respectively. The color of semen was not consistent pattern, it varied as creamy white and milky white. The motility of fresh and post thaw semen was assessed as 73.9 vs 48.75%; 75 vs. 53.75%; 75 vs. 53.12% for the month of May, June and July respectively. The membrane integrity of fresh semen samples over a period of three month were 58.37% against post-thaw membrane integrity of 44.79%. It was concluded that the semen of Holstein Friesian bull tolerates freezing and thawing stress and maintained reasonable good fertility. The summer season has no significant adverse effect on quality of semen.
Keywords: Bull; Fresh; Holstein Friesian; Post-thaw; Quality; Semen