Quality of Ongole bull sperm after storage in CEP-2 extender containing different extracellular cryoprotectans

Quality of sperm must change during storage either in refrigerator or freezer temperature, at least by cold shock. This study is aimed to evaluate the ultrastructure and quality of Ongole bull sperm after storage at 4 °C (refrigerator temperature) in cauda epididimal plasm (CEP-2) based extender fortified with three different extracellular cryoprotectans as treatment, i.e. 10% egg yolk, 10% coconut milk and 5% skim milk. The sperm quality were observed for motility (%), viability (%), and abnormality (%) on day 0 to 8^th day of storage. The data of sperm quality were transformed into archive before being analysis with ANOVA and Duncan's multiple range tests. The result showed that lower proportion (3.6+0.97%) of morphologically abnormal sperm was found after storage in CEP-2 with 20% egg yolk extender, whereas lower morphologically abnormal sperm was found in semen after storage in CEP-2 with 10% coconut milk or 5% skim milk, especially for fractured neck and destroyed head sperm. The percentage of motile Ongole bull sperm after eight days of storage were significantly higher in CEP-2 with 10% egg yolk extender (43.5 + 2.4%) as compared to those in CEP-2 with 10% coconut milk or 5% skim milk (0%). Thus, the use of 10% egg yolk extracellular cryoprotectan in CEP-2 extender had potential in maintaining quality of sperm during storage at refrigerator temperature for eight days.