Soybean milk extender improves sperm functional and oxidative stress parameters of goat sperm during slow and rapid freezing

The objective of this study was to determine effects of soybean milk extender on sperm quality end points of cryopreserved goat sperm. Pooled ejaculates from West African Dwarf (WAD) goats were diluted with various amounts (0, 5, 10, 15, 20 ml) of soybean milk (SBM) in Tris-extenders, subjected to slow or rapid freezing for 30 days and subsequently thawed and evaluated. Inclusion of SBM in extenders improved sperm quality (P < 0.05) compared to control (egg yolk-based extender) for both slow and rapid freezing methods. Semen cryopreserved with 10 or 15 % SBM extender had higher (P < 0.05) motility compared to other concentrations and the control using slow freezing. Although both cryoprotocols had higher (P < 0.05) acrosome integrity when cryopreserved with 20 % SBM extender, acrosome integrity at 20 % SBM was higher (P < 0.05) in rapid freezing compared to slow freezing. Semen cryopreserved with SBM extenders had lower (P < 0.05) Malondialdehyde (MDA) concentrations in 10 to 20 % SBM extenders for both freezing methods, although MDA concentrations were lower (P < 0.05) in slow freezing compared to rapid freezing. Semen cryopreserved with SBM extenders in both protocols had fewer (P < 0.05) leukocytes and a higher (P < 0.05) acrosome reaction and sperm capacitation, whereas there was a higher (P < 0.05) acrosome reaction with 10 and 5 % SBM extenders using slow and rapid freezing respectively. In conclusion, for goat semen cryopreserved using slow or rapid freezing protocols, SBM extenders improved functional, fertilizing and seminal oxidative stress end points.