The reproductive value of enrichment to sows at farrowing

Pre-parturient sows in traditional farrowing environments are confined at a time when they are highly motivated to perform nest building behaviours (Westin et al. 2015). Providing them with hay may help alleviate the frustration associated with confinement, and lead to welfare improvements for the sow and her piglets. In this study, sows were provided with lucerne hay, which acted as a food-based enrichment and nest building material, and the impact on reproductive performance was studied. It was hypothesised that the provision of lucerne would reduce parturition time and decrease the number of stillborn piglets.

Sixty-nine Large White x Landrace sows (Parity 0 to 2) over six farrowing batches were allocated to either the Control (n = 33) or Lucerne enrichment (n = 36) treatments. Prior to farrowing (6.5 ± 0.3 days), sows receiving enrichment were given ~1 kg of lucerne hay/d into their feeding trough after their morning ration. Weaning occurred at 16.4 ± 0.3 days. Current farrowing duration and piglet numbers and outcomes were measured from video observations. Subsequent mating performance was taken from farm records. All data were analysed to assess the effects of enrichment. In SPSS (v24.0, IBM, Armonk, NY, USA), general linear models with parity, treatment and their interaction as fixed effects, and batch as a random term, were run for the following variables: farrow duration (log₁₀), piglet interval (log₁₀), total piglets born, piglets born alive, and piglets weaned. A covariate of total number of piglets born was added to the model for farrowing duration (from first piglet to last) and piglet interval only. The same model was used for number of piglets born dead and post-natal piglet deaths but a generalised linear model with Poisson distribution was applied, and a binomial distribution was applied to the number of sows that were mated the next batch. The number of piglets born dead was reduced by 0.3 piglets in the lucerne treatment (Table 1). There was no difference in farrowing duration, piglet birth interval, total number of piglets born, or piglets born alive. A significant parity by treatment interaction existed for percentage of sows mated within the batching requirements. Sows displaying oestrus within 2 weeks of weaning were bred, whilst the remainder were not bred that batch. More gilts from the Lucerne treatment were mated immediately following weaning (81%) than Controls (60%), but this relationship was reversed in multiparous sows (Lucerne 67% v. Control 90%; P < 0.05).

Table 1.  The effects of the provision of lucerne before and at parturition on sow reproductive performance

The difference in number of piglets born dead in the absence of any change in farrowing duration is intriguing. One possible explanation is that allowing the sow to perform nest-building activities had positive effects on uterine blood flow and so risk of piglet hypoxia was reduced. This notion needs confirming. Behaviour at parturition from this experiment is being analysed to assess if this contributed to the difference in the number of stillborn piglets. The finding that gilts may show improvements in re-breeding success is interesting, but viewed with caution given the short lactation length and consequent poor subsequent performance. This experiment is being replicated on a larger scale in a commercial piggery, and the nutritional impacts of lucerne are being quantified to evaluate these results further.