Greater potentiality of sperm membrane bound fertility associated antigen to withstand oxidative stress ensuing improved sperm function of cryopreserved bull spermatozoa

Fertility associated antigen (FAA) are more abundant in semen of bulls with high fertility. The objective was to investigate relationship of FAA, either membrane bound and/or in seminal plasma, with that of markers of oxidative stress, mitochondrial activity and acrosome integrity of live cells, in cryopreserved spermatozoa. Grouping of bulls was done by electrophoretic profiling of proteins from seminal plasma (SP), and sperm membrane (SM), based on presence/absence of the FAA in SP and/or SM or both. Group I had detectable FAA in both SP and SM; Group II, FAA detected only in SM; Group III, detectable FAA only in SP and Group IV, undetectable FAA in both SP and SM. At post-thaw stage, the lipid peroxide levels were significantly lower (p<0.05) and the activity of primary free radical scavengers (superoxide dismutase and catalase) was significantly higher (p<0.05) in Groups I and II. Correspondingly, Group I and II showed significantly higher (p < 0.05) per cent of acrosome intact live spermatozoa and sperm cells with functionally active mitochondria. Collectively, this study showed that the presence of FAA on the sperm membrane is related to greater protection against oxidative stress ensuing improved acrosome intact live-sperm cells with functional mitochondria.