Osmotic Tolerance and Freezability of Beetal Goat Sperm during Breeding and Non-Breeding Seasons

The present study was conducted to determine seasonal variations in osmotic tolerance and post-thaw qual-ity of Beetal goat sperm. The ejaculates (n=12) were collected from mature bucks (n=3) during breeding (late summer-early fall) and nonbreeding (winter-early spring) seasons. In the first experiment, the samples were exposed to hypo-osmotic, iso-osmotic, and hyper-osmotic conditions adjusted to 50, 100, 290, 500, or 1000 mOsm/L and incubated at 37 C for 15 min. After the osmotic challenge, sperm viability and plasma membrane integrity (PMI) were determined using a combined hypo-osmotic swelling test (HOST) and eo-sin-nigrosine staining. In experiment 2, the ejaculates were diluted with a tris-citric acid fructose (TCF) extender and frozen in liquid nitrogen following a standard protocol. After freezing, samples were thawed to assess motility, motion kinetics, PMI, and viability. The results showed a significant (P<0.05) impact of the interaction between osmolality and season on live-HOST +ve and total-HOST +ve sperm. The live -HOST +ve and total-HOST +ve sperm were higher (P<0.05) in the breeding season. Post-thaw sperm PMI, progressive and total motilities were higher (P<0.05) in the breeding season; while, viability and sperm motion kinetics were similar (P>0.05) between the seasons. In conclusion, the season impacts the osmotic tolerance and cryopreservation of Beetal goat sperm.