Using of Cottage Cheese Whey with or without Egg Yolk as a New Dilution for Cryopreservation of Ram Semen

The aim of this study was to evaluate using whey of cottage cheese as a diluting agent for ovine semen. Semen from five rams were collected, pooled, and divided into 3 parts, and diluted (1:20) using three solvents: Tris-15% egg yolk extender (E1, control), whey-cetric-10% egg yolk extender (E2), and whey alone (E3). The diluted semen was then allowed to equilibrate (5 oC for four hours), then frozen (-196 oC). After thawing, semen was assessed by Computer Assisted Semen Analyzers (CASA) program for progressive motility (PM), live sperm (LS), acrosome integrity (AI), abnormality (AB), and DNA damage of spermatozoa. Results showed that the percentages of LS, and AI in post-thawed semen were higher (P<0.50) and the proportion of chromatin damage was lower (P<0.05) with E2 than in other extenders (E1 and E3). Comparing E2 to other extenders, post-thawing semen examined by CASA showed improved (P<0.05) percentages of progressive, rapid progressive, and total motility, and decreased immotility. E2 showed significantly (P<0.05) higher VSL than in E1 and E3 with the highest LIN and STR percentages. E3 showed significantly (P<0.05) higher VCL and VAP than in E1 and E2 with the lowest LIN and STR percentages. Conclusion: Cottage whey-10% egg yolk can be used as an extender for ram semen cryopreservation. It increased the freezing ability of ram spermatozoa by improving most sperm characteristics as compared to Tris-egg yolk extender.