Cryopreservation of Nili-ravi Buffalo Bull Sperm in Cryodiluent Supplemented with Lolium Perenne Protein Preparations

BACKGROUND: Semen from the Nili-Ravi buffalo bull, Bubalus bubalis, shows poor survival after freeze storage compared to bovine (Bos taurus and Bos indicus) semen. Freeze-susceptibility distinctions in these two genera have been attributed to differences in sperm membranes. MATERIALS AND METHODS: We measured the impact of protein preparations derived from a frost-resistant perennial grass, Lolium perenne, with ice recrystallization inhibition activity on the low temperature storage of B. bubalis semen. RESULTS: When the L. perenne preparations (0.1, 1, 10 μg/mL) were added to buffalo semen [2 ejaculates per bull (N=3) per replicate (r=3)] in Tris-citrate extender (50×10⁶ sperm mL^-1), there was no impact on semen quality, as measured by sperm motility and plasma membrane integrity, after storage at 4ºC (P >0.05). However, when semen supplemented with the grass proteins (0.1 and 1 μg mL^-1) was evaluated after freezing and storage in liquid nitrogen for 24 h, post-thaw sperm progressive motility and plasma membrane integrity was higher (P <0.05) than in control samples. Post-thaw sperm viability and sperm acrosome integrity was similar (P >0.05) to controls. CONCLUSION: The improvement in cryopreserved buffalo sperm progressive motility and plasma membrane integrity suggests that the use of these easily-made preparations may improve fertility after cryopreservation and offers the prospect of improved conception rates after artificial insemination with cryopreservation.