Functional variables of bull sperm associated with cryotolerance

Abstract

The objective of this study was to ascertain sperm population and cellular characteristics as well as total antioxidant capacity in spermatozoa from Holstein bulls with Good (11 bulls) and Poor (5 bulls) cryotolerance. Post-thaw sperm kinetics were evaluated using CASA, membrane integrity was assessed via HOS test, and DNA fragmentation was measured using the HaloSperm kit. Data were analyzed using principal component analysis. The spermatozoa from Good bulls had a higher number of cells with intact membranes (P=0.029), non-fragmented DNA (P=0.018), and post-thaw viability (P<0.001) compared to sperm cells from Poor cryotolerance bulls. Sperm cells from Good bulls also had a faster average path velocity (P=0.017) and straight-line velocity (P=0.036), along with a greater distance average path (P=0.006) and distance straight line (P=0.011). However, total antioxidant capacity, number of live cells, and other kinetic parameters between spermatozoa from Good and Poor groups were not different. There is no one specific sperm function variable alone that can accurately predict cryotolerance of bull spermatozoa, and thus, a combination of sperm cell attributes and kinematics needs to be utilized by the AI industry in differentiating between freezability of spermatozoa between bulls.