Enrichment at weaning can reduce piglet stress

By Ashlyn Scott & Meagan King

Editor’s note: Ashlyn Scott is a graduate student with the Department of Animal Science at the University of Manitoba. She can be contacted at ‘scotta12@myumanitoba.ca.’ Meagan King is an assistant professor with Department of Animal Science at the University of Manitoba. She can be contacted at ‘meagan.king@umanitoba.ca.’

Ashlyn Scott was the first-place winner of the R.O. Ball Young Scientist Award at this year’s Banff Pork Seminar. The award recognizes graduate students who provide a best overall combination of good and relevant science, a well written abstract and an excellent presentation.

Weaning is a stressful time for piglets. When weaned, they can be stressed because of sow separation, transportation and re-mixing. Our recently completed research project looked at ways to mitigate piglets’ stress around weaning to improve their behaviour, welfare and performance.

When looking for ways to mitigate piglet stress around weaning, finding solutions beneficial to piglets and feasible for large-scale producers can be challenging. This project took place in the summer of 2022 at a 6,000-sow operation.

The research team supervised by Meagan King compared the outcomes of two enrichment types and their combined effect: object enrichment and social enrichment. Object enrichment included hanging burlap in farrowing and nursery pens using C-clamps to secure the sheet over the plastic pen panels, while social enrichment included allowing groups of two or four neighbouring litters to mix before weaning by removing the plastic pen dividers when piglets were approximately three-days-old.

The team recorded piglet behaviour, piglet body weights, and sow and piglet lesion scores. The results indicate that each type of enrichment was able to be implemented in a commercial setting and benefitted the piglets.

Evaluating enrichment options

Figure 1: Laid-on piglet deaths as a proportion of total piglets

By mixing piglets with other litters before weaning, the animals get the chance to interact with other piglets in a familiar environment, with their sow present, while developing social skills that they can use once weaned and mixed with unfamiliar pigs again in a new environment. Using this method, piglets are also provided with more space per pig when the dividers are removed, and more safe space is available away from the sow. In our trial, this significantly reduced the number of laid-on deaths – percentage of piglet deaths that were a result of being crushed by the sow (Figure 1).

Mixing piglets in groups of four litters before weaning decreased the amount of biting by weaned piglets, and as a result, improved their lesion scores one-week post-weaning. Before weaning, sow udder and teat condition also deteriorated less when piglets were mixed with four neighbouring litters. Mixing did not affect piglet weaning weights or total mortality.

By providing burlap in the pens, piglets are encouraged to engage in natural behaviours, such as chewing, rooting and exploring, and there is an element of familiarity between their environments before and after weaning. Having access to burlap reduced biting behaviours between piglets before and after weaning, because they had a more positive outlet for their chewing behaviours and performed less fighting and biting. As a result, fewer lesions were observed after weaning. 

Access to burlap also reduced the amount of manipulation of pen objects, potentially improving the longevity of the pens, flooring and feeders. Results indicate providing burlap did not affect piglet weights or mortality one week after weaning. Average daily gain was not measured; however, other studies have found that access to burlap improves weaners’ feed intake. Feed intake is improved because the piglets’ jaw and facial muscles are more developed after chewing on burlap. This practice also improves their transition to solid feed following weaning.

Figure 2: Factors related to each type of enrichment

Both types of enrichment benefitted the piglets; however, their effects were not additive, meaning that either object or social enrichment can be implemented by producers, depending on preference and suitability to their operations. When deciding which enrichment type might have a greater impact on-farm, some key factors to consider are cost, biosecurity and welfare (Figure 2).

Overall, both types of enrichment allow piglets to socialize with others at a younger age and redirect their attention and aggression away from each other, which does not negatively impact performance and can improve behaviour around weaning.

Getting a better feel for burlap

Currently, our team has a follow-up project to evaluate if the timing of burlap presentation is important. For this project, there are four treatments: piglets have access to burlap only in the nursery; piglets have access to burlap only in the farrowing room and nursery; sow and piglets have access to burlap in the farrowing room, and piglets have access to burlap in the nursery; sows and piglets have no access to burlap.

The results of this project should indicate whether piglets need previous exposure to burlap in the farrowing room in order to benefit from it at weaning, and whether they learn from their sow to engage with burlap.