Ultrastructure and fertilizing ability of Limousin bull sperm after storage in CEP-2 extender with and without egg yolk

Sperm can change physiology and structure during storage in refrigerator temperature or frozen temperature that caused by cold shock or free radical. The aim of this study to evaluate ultrastructure and fertilizing ability of Limousin bull sperm after storage in cauda epididymal plasma-based (CEP-2) extender with or without 20 egg yolk concentration at refrigerator temperature. Semen sample collected from three Limousin bull were diluted with CEP-2 with 20 egg yolk and CEP-2 without egg yolk, cooled and stored at 4-5?C during eight days. Sperm ultrastructure were observed with scanning electron microscopy (SEM). Fertilizing ability of Limousin bull sperm were assessed on cleavage rate of embryo using in vitro fertilization method. The percentage data were transformed into arcsine before being analysis with ANOVA and Duncan s multiple comparison test. The result of study showed morphologically normal sperm after storage in CEP-2 with 20 egg yolk, whereas in CEP-2 without egg yolk morphologically abnormal sperm especially neck was fractured and head was destroyed. Fertilizing ability of Limousin bull sperm were significantly higher in CEP-2 extender with egg yolk 20 (74.29?4.95 ; p