Managing sow reproductive performance through lactational oestrus induction

Abstract

Efficient reproductive performance of sows in the pork industry is of utmost importance for maximum productivity. Producers have previously remained limited in options for managing reproduction and relied on weaning sows before mating. This thesis investigates the reproductive efficiency of sows through the incidence of spontaneous lactational oestrus and the effects of stimuli on lactational oestrus induction. The first experiment highlighted that the incidence of lactational oestrus was 15, 41 and 23% in control sows, sows stimulated with Pregnant Mare Serum Gonadotropin and Human Chorionic Gonadotropin or boar exposure alone, indicated by the presence of mature ovarian corpora lutea. The second experiment indicated that sows mated within 28 d of parturition was reduced when subjected to either the 8h piglet separation or full boar exposure (53.2 and 75% respectively) compared to sows from 16h piglet separation and control treatments (82 and 93.5% respectively). Ovarian follicular development under different suckling loads was explored in the third experiment, highlighting no significant correlation between weaned litter sizes and follicular growth during lactation. Following this, primiparous sows were studied under the use of split or intermittent suckling, boar exposure and skip-a-heat techniques. Only 37.9 and 42.5% of intermittent and split suckled sows showed lactational oestrus. The final experiment in this thesis compared the incidence of lactational oestrus in sows housed in farrowing crates, PigSAFE pens and group housing. Oestrus behaviour, ovarian follicular size and WRI suggested that between 3.1 and 20.7% of sows across all treatment groups’ likely experienced lactational oestrus. Stimulating sows to ovulate and mate during lactation opens the industry to the possibility of extending lactation length and improving piglet performance whilst maintaining productivity.