The usefulness of combining traditional sperm assessments with in vitro heterospermic insemination to identify bulls of low fertility as estimated in vivo

Abstract To date, no single in vitro assessment can estimate bull fertility. This research was aimed at evaluating the ability of a series of laboratory assessments to assign 50 Holstein Friesian bulls grouped as low (ER-NRR  Low fertility bulls had lesser ( P P r  = 0.30), progressive motility ( r  = 0.26), membrane integrity ( r  = 0.43) and % DFI ( r  = −0.26). While % DFI alone allowed the identification of 70% lowly fertile bulls, combining membrane integrity, average path velocity and CBI allowed for identification of 78% of the lowly fertile sires. Paternal assignment by SNPs resulted in 96% of successful assignments and could provide an alternative support to microsatellites for in vivo studies based on heterospermic fertilization for estimating fertility.