The present study was planned to study the effects of different concentrations of catalase enzyme (CE; 0, 250, 500 and 1000 IU/ml) addition to the extended cooled dromedary camel semen (DCS) with Tris-yolk-fructose (TYF) extender on semen quality and enzymatic activities, during storage at 5?C for up to 5 days. Conception rates of she-camel artificially inseminated with whole fresh or extended cooled camel semen without or with 500 IU/ml CE, were also estimated. The results showed that supplementation of CE at 250 or 500 IU/ml to the extended cooled DCS increased significantly the percentage of sperm motility and decreased significantly the percentage of dead spermatozoa, sperm abnormalities and acrosomal damage. Also, supplementation of CE at 250 or 500 IU/ml decreased significantly the amounts of aspartate-aminotransferase (AST), alanine-aminotransferase (ALT) and alkaline phosphatase (ALP) enzymes released into the extracellular medium during storage at 5?C. The highest value of the percentage of sperm motility was recorded with the extended cooled DCS supplemented with CE at 500 IU/ml and the lowest value was recorded with CE at 1000 IU/ml. While, the lowest value of the percentage of dead spermatozoa, sperm abnormalities, acrosomal damage of spermatozoa were recorded with the extended cooled DCS supplemented with 500 IU/ml and the highest value were recorded with CE at 1000 IU/ml. The advancement of storage time at 5?C decreased significantly the percentages of sperm motility and increased significantly the percentages of dead spermatozoa, sperm abnormalities, acrosomal damage of spermatozoa and the amounts of AST, ALT and ALP enzymes released into the extracellular medium.
