Equine chorionic gonadotrophin and porcine luteinizing hormone to shorten and synchronize the wean-to-breed interval among parity-one and parity-two sows

Abstract

Objective: To determine the efficacy of an estrus and ovulation synchronization protocol utilizing equine chorionic gonadotropin (eCG) and porcine luteinizing hormone (pLH) on the wean-to-breed interval (WBI), farrowing rate, and litter size in parity-one and parity-two sows. Materials and methods: Parity-one (n = 1167) and parity-two sows (n = 1196) from a total of eleven farms across Canada were each randomly assigned either to a treatment (596 parity-one and 599 parity-two sows) or control group (571 parity-one sows and 597 parity-two sows). Treated sows received 600 IU eCG intramuscularly (IM) at weaning and 5 mg pLH IM at observed estrus. Detection of estrus behaviour was facilitated by twice daily boar exposure for 20 minutes beginning 24 hours after weaning. All sows were inseminated at 12 and 32 hours after the onset of behavioural estrus. Results: On average, the WBI was lower by approximately 1 day among treated parity-one sows, and by 0.3 day among treated parity-two sows. In addition, the overall breeding period was shorter among treated sows, especially among parity-one sows. There was no treatment effect on farrowing rate or litter size. Implications: Administration of exogenous eCG and pLH with subsequent timed double insemination may shorten the WBI in weaned parity-one and parity-two sows, allowing for more predictable crate utilization and a narrower range in gestational age in the farrowing room.