Benefits of synchronizing ovulation with porcine luteinizing hormone (pLH) in a fixed time insemination protocol in weaned multiparous sows.

Materials and methods: Multiparous sows were randomly assigned to treatment at weaning. From weaning, twice-daily boar exposure facilitated estrus detection. Untreated control sows (n = 150; CONT) were artificially inseminated at least twice. Treated sows (n = 168; LUT) received 5 mg pLH intramuscularly concomitant with the first detection of standing heat. To coincide with the normal working day, sows in estrus in the morning were inseminated at 24 and 30 hours (am and pm), while sows in estrus in the afternoon were inseminated at 24 and 42 hours (pm and am), after pLH administration.