at 4°C for 4 days was Incubation of bull spermatozoa with PGF2 a performed to investigate the effect of PG on some sperm cell characters and enzymatic release. Semen from cross-bred bulls (Balady X Fresian) was diluted with egg yolk citrate at a rate of 1:10. Aliquots were
supplemented with PGF2 a in levels of 0, 200, 400 and 600 ug ml and stored at 4°C for 4 days. Daily examination for each treatment was carried during the storage period. The percentage of sperm motility (SM%), alive sperm (AS%) and sperm with intact acrosome (IA%) w decreased significantly with doses higher than 200 ug ml. In the same time, abnormal sperm percentage (AbS%) increased in samples which contain 400 and 600 ug ml. Continuous increase in transaminases activities in the extra-cellular medium were noticed with the increase level of PGF2 a and prolongation of storage time. The results suggested that, addition of PGF2 a with high concentration (more than 200 ugl ml) to bull spermatozoa during storage at°C adversely affect sperm motility, viability and abnormalities as well as induced membrane damage and impair permeability.