24 August 2001

Piglets thrive after mixing

By Hannah Velten

Indoor weaning of pigs is traditionally an abrupt, stressful process which can result in an immediate check in piglet performance. But mixing litters before weaning appears to gradually acclimatise piglets to different social conditions.

Reducing stress at weaning is part of the strategic prevention of pig wasting diseases, says Alan Stewart, senior lecturer at Harper Adams University College. The Shropshire college has an ongoing study of pre-weaning management with the aim of helping piglets adapt to weaning and ultimately increasing performance right through to slaughter.

"Psychological stress endured by indoor pigs, particularly aggression, when weaned into new social groups away from their mother contributes to growth checks in the following five days. Pig feed intakes can drop to 50g/day immediately after weaning, so growth rates fall from 250-350g/day to 0-150g/day.

"This can result in immunity falling and disease taking hold. With margins tight in pig production, every avenue should be investigated to prevent mortality and increase long-term performance," says Mr Stewart.

This led the college to look at mixing piglets before weaning. Pre-mixing of piglets before weaning is not a new idea. Studies at Aberdeen University in the mid-1990s introduced 14-day-old piglets to a multi-suckling system, which helped reduce weaning performance check.

However, some piglets were squashed because sows were loose, housed on straw and the system required high-labour input, he adds.

Mr Stewarts student, Laura North, set out to prove a similar multi-suckling system would work inside farrowing units. Newport-based pig producer Anthony Glover had been mixing three litters of pigs before weaning for several years, so research began on his unit.

Two blocks of 12 sows and their litters were used. In each study six litters were unmixed and the others mixed at 14 days old. By removing dividing partitions between pens, three litters were run together, while creep feed was available ad-lib. Weaning took place at 24 days and whole litters were put into pens containing two litters.

Results showed that pre-mixed piglets had greater weaning weights and post-weaning performance and fighting also reduced (see table).

In practice, there was no extra piglet mortality due to sow aggression, cross-suckling occurred and sows synchronised lactating patterns, adds Mr Stewart.

Many commercial units could easily take up this simple and cheap method of mixing piglets, but Mr Stewart warns not to include scouring litters or use aggressive sows.

Further research using the colleges high-health herd by another student, Mary Allen, shows that early mixing at seven days old and mixing late at 21 days have a less positive effect on long-term weaning performance than mixing at 14 days.

Mixing of less than three litters also gives no beneficial effect because behavioural problems occur in piglets.

The Harper Adams pig unit continues to be used to research ideal pre-weaning management. "Other weaning management avenues are being investigated, such as whether there are economic benefits from leaving litters in the farrowing pen for a few days after the sow is removed," says Mr Stewart. &#42

Results of pre-weaning mixing of piglets

No mix Pre-mix

Pre-weaning growth rates (g/day)

Day 14-17 321 403

Day 17-24 368 425

Post-weaning growth rates

Weaning 25.7 77.3

+ 5 days

Day 5-22 580 602

Lesion scores 5 dayspost-weaning (0-5)

2.39 0.58