Fertility of lactating dairy cows inseminated with sex‐sorted or conventional semen after Ovsynch, Presynch–Ovsynch and Double‐Ovsynch protocols

Abstract

The objective was to compare pregnancy per artificial insemination (P/AI) with conventional (CS) or sex-sorted semen (SS) in dairy cows subjected to one of the three timed AI protocols. Cows (n=356) were randomly assigned to synchronization with Ovsynch (OVS), Presynch-Ovsynch (PO) or Double-Ovsynch (DO) and inseminated on Day 77±3 postpartum with either frozen-thawed SS (n=182) or CS (n=184) of the same bull. More cows were cyclic at the beginning of breeding Ovsynch increased (p<0.01) with presynchronization and it was greater for DO than PO (OVS=78.5%, PO=85.1%, DO=95.6%). Overall, P/AI for SS and CS increased with presynchronization (p<0.05) on Days 31 (OVS=35.5%, PO=47.1%, DO=48.3%) and 62 (OVS=30.1%, PO=43.8%, DO=43.9%). Regardless of synchronization treatments, insemination with SS reduced P/AI (p<0.02) on Days 31 (38.1% vs. 50.6%) and 62 (34.5% vs. 45.6%) compared with CS. No interaction was observed between synchronization treatment and type of semen for P/AI, although in cows receiving CS, P/AI was numerically greatest for PO (OVS=42.0%, PO=59.3%, DO=49.0%), and in cows receiving SS, it was numerically greatest for those inseminated following DO (OVS=27.9%, PO=35.5%, DO=47.6%). Thus, presynchronization improved P/AI in cows inseminated with sex-sorted or conventional semen.