Higher feed intake, better piglet behaviour

Confinement in pig production has been a topic of serious debate over the last decades. An ongoing welfarist call for more freedom for gestating sows has led to the animals being kept in group housing in an increasing number of pig houses all over the world. It doesn’t stop there – in Scandinavia, for instance, freedom during farrowing is increasingly being promoted.

Understandably, there can be quite some frowning observed around this tendency to give more liberty to production animals. How to avoid crushing and fighting for instance? And what if all this welfare comes at a substantially higher cost of production?

Multi-litter system

Interesting in this respect is recent research that was done using a so-called ‘multi-litter’ (ML) system. This farrow-to-wean system unites a range of liberties that can be given to sows and piglets. A recent study, published in the midst of 2015, was carried out by Sofie van Nieuwamerongen and a team of researchers from Wageningen University, with the trials carried out at the Swine Innovation Centre Sterksel, the Netherlands. The trial aimed to quantify performance of sows and piglets in an ML system compared with a conventional ‘single-litter’ (SL) system with a crated sow. Based on pigs’ natural behaviour, the ML system allows sows to farrow freely in 1 of 5 farrowing pens measuring 2.4 x 3.0 m each. Each pen had 5 hessian sacks as nesting material. The social structure of the sows is kept intact by allowing the sows to use the communal area (divided in an area for lying, feeding and defecating/urinating) continuously. Only during nights before farrowing, sows were locked in their own farrowing pen. Social development of piglets is stimulated by providing contact among the 5 litters from 1 week of age, by giving them access to the communal area.
Moreover, early feed intake is stimulated as piglets can learn to eat from the sows and other piglets in the communal feeding area. After weaning at an age of 4 weeks, ML piglets were housed in enriched pens in a group of 40 piglets (0.42 m² per piglet).

Trial set-up

The multi-litter system was evaluated in 5 rounds. Every round, 5 gestating sows were allocated to the ML system, and 5 to an SL system. In both cases, the initial number of piglets per sow was equalised – either by adding or taking away piglets. At weaning, 10 healthy animals were selected out of 4 litters each, as much as possible equally divided over gender. The weaned piglets in the control group were kept in 4 groups of 10 littermates.

The animals were scored for a wide range of criteria. Amongst others, sows were scored for weight, feed intake, number of piglets born and lesions; in piglets, weight, veterinary treatment, lesion scores, behaviour and blood were recorded; and finisher pigs were followed on elements like weight, feed intake, veterinary treatment and slaughter quality.

Results of the trials

Several results were found to be identical in both trial set-ups – in those cases the ML management system did not show any better or worse results. In sows, loss of weight and backfat during lactation for instance were found to be similar. In piglets, no difference was found in aggressive behaviour before and after weaning, just as in post-weaning mortality, the number of individual veterinary treated piglets, the performance and slaughter quality.

As might be expected, the researchers also found several effects in the ML system that could be qualified as less positive. Sow feed supply in multi-litter systems was found to be higher than in single-litter systems. The researchers write that this could have been caused by the fact that piglets had access to this feed; but it could also have been the result of the fact that sows needed a higher feed intake as they simply had a higher maintenance requirement due to their movement.

In addition, more teat lesions were found to occur in ML sows than with SL sows, which might be related to (low levels of) cross-suckling. Last but not least – and probably expected – pre-weaning mortality was higher in ML sows than with SL sows; this was 3.2 per litter compared with 1.5 per litter. This was mainly caused by crushing by sows in the first days after farrowing, which was linked to a suboptimal farrowing pen layout.

Positive outcomes

Interestingly, however, are the positive outcomes of the ML system. The Table summarises some of the results of the trials and highlights one of the outcomes: pigs that were reared in a multi-litter system actually had a higher feed intake and daily gain after weaning and were less affected by diarrhoea. In other words, ML housing resulted in a better transition from the pre-weaning to the post-weaning situation for the piglets.

Behavioural observations showed that ML piglets had a lower frequency of damaging oral manipulative behaviour before and after weaning. Pre-weaning levels were 3.6 times per hour in the SL housing and 1.4 times per hour in the ML housing and applied to chewing on all body parts, including tails and ears. ML piglets also showed more feed-directed behaviour at 2 weeks of age. In addition, a higher frequency of post-weaning play behaviour was observed –on average 2.8 times per hour in SL housing and 4.0 times per hour in ML housing, although these figures were not significantly proved. These behaviours are an important sign of welfare and relevant in the development of (social) behaviour.

Conclusion

ML housing resulted in a better transition from the pre-weaning to the post-weaning situation for the piglets, resulting in improved performance and welfare. An economic evaluation still needs to take place.

With permission, this article has been based on the scientific report ‘Development of piglets raised in a new multi-litter housing system vs. conventional single-litter housing until 9 weeks of age’ (2015) and ‘Groepskraamsysteem: analyse van de ontwikkeling van zeugen, biggen en vleesvarkens’ (2015).