Influence of ?-glutamyltransferase and alkaline phosphatase activity on in vitro fertilisation of bovine frozen/thawed semen

The aim of this work was to evaluate whether the residual amount of γ-glutamyl-transferase (GGT) and alkaline phosphatase (ALP) in bovine sperm after freezing/thawing is correlated with fertility parameters, including blastocyst rates after in vitro fertilisation (IVF). The enzyme activities were determined in both spermatozoa and supernatant after centrifugation. While ALP was only correlated with sperm viability, GGT activity was correlated with sperm motility (rs = .4; p < .05) both in sperm and supernatant. Interestingly, GGT activity was also correlated with cleavage (rs = .5; p < .05 and.8; p < .01, for sperm and supernatant respectively) and blastocyst (rs = .6 and.9, for sperm and supernatant respectively; p < .01) rates obtained after IVF. These results suggest that GGT could play an important role in the protection of sperm against oxidative stress and could be considered a reliable marker to assess frozen/thawed sperm quality in bovine.