Effect of Goat Milk Supplementation in Semen Extender on the Motility of Post-Thaw Goat Sperm

Abstract

       This study aimed to determine the effect of different milk supplementation in semen extenders on the post-thaw motility of goat spermatozoa. Semen samples were collected from three Boer crossbred bucks. For semen collection, goat semen was collected once a week for six consecutive weeks, and each ejaculate was divided into three equal parts. Each part was diluted with one of three different Tris (hydroxymethyl) aminomethane-based extenders: Tris + egg yolk, Tris + goat milk, or Tris + cow milk. The diluted semen was cooled at 4 °C for 4 hours, then exposed to liquid nitrogen vapor at −121 °C for 13 minutes, after that it was plunged into liquid nitrogen at −196 °C for storage. After 24 hours of cryopreservation, frozen goat semen samples were then randomly selected from each male in each treatment group, with six samples per week, for a total of six collections. The post-thaw sperm quality was evaluated by using Computer Assisted Sperm Analysis (CASA) system to measure sperm motility parameters. The results revealed that the Tris + goat milk extender had the highest total motility (p < 0.01) compared with Tris + egg yolk and Tris + cow milk. The progressive motility of spermatozoa in the Tris + goat milk group was higher (p < 0.05) than the other treatments. No significant differences (p > 0.05) were found in other motility parameters (path velocity; VAP), (straight-line velocity; VSL), (straightness; STR), (curvilinear velocity; VCL), (linearity; LIN) and (beat cross frequency; BCF). However, the amplitude of lateral head displacement (lateral head displacement; ALH) was higher (p < 0.05) in the Tris + egg yolk extender than those containing cow or goat milk. In conclusion, the Tris + goat milk extender was more effective than other extenders in preserving the post-thaw total motility of goat spermatozoa. Therefore, goat milk is an alternative extender for efficiency of goat semen.