Lactation management top of the agenda at pig conference

Lactation management and oestrus stimulation were some of the topics discussed at a recent BPEX Breeding event in Milton Keynes. Aly Balsom reports

About 25% of sows could be experiencing reduced litter size in their second parity because of less-than-ideal lactation management, according to Bas Kemp, scientific director of the Wageningen Institute of Animal Sciences, The Netherlands.

“On average, a farm may not appear to have issues with second litter size but, in reality, a quarter of sows could be producing fewer piglets.”

And weight at first weaning has a significant influence on performance, with sows weighing less than 150kg experiencing a drop in litter size of 1.2 piglets from 11.1 to 9.9 in the second parity.

“This effect will be repeated throughout subsequent parities, with sows experiencing second litter drop (SLD), likely to be culled one parity earlier than other individuals,” he said.

However, SLD can be prevented by addressing feed intakes during lactation. “It is important to prepare for lactation intakes by implementing good gilt management.

“Don’t over feed gilts at the end of pregnancy as this can result in lower intakes during lactation and increased piglet mortality. But equally, underfeeding should also be avoided as a sow’s ability to compensate in lactation is limited.”

Risk factors for reduced feed intake come from providing high volumes of food too quickly in early lactation, resulting in a rapid increase in body temperature, and a reduction in overall feed consumption. “Feed intakes will never recover and there will be a long-term reproduction effect on future parities,” said Prof Kemp.

To prevent this, feed should be built up gradually from 2kg a day in the first week after farrowing to ad lib. “It is possible to repair second-litter syndrome through skipping a heat; a Canadian study found doing so resulted in an increase in litter size of 2.5 piglets from 10.4 to 12.9.”

And feeding levels at the start of pregnancy also have a significant effect on pregnancy viability, he said. “It’s important not to over feed gilts in the first 10-14 days of pregnancy as this can result in a 10% increase in embryo mortality.

Feeding restricted diets of 1.1-1.5 times maintenance levels directly after insemination gives the best results in gilts. Those on a restricted diet showed 20.6% embryo mortality compared to 29.9% mortality in gilts receiving high feeding levels.

However, these results were only seen in gilts. “Because sows are coming out of lactation and need to restore body weight, it is questionable whether this strategy would work with pigs at this stage.”

Research looking at the effect of early pregnancy feeding on sows found sufficient feeding was crucial for reproduction. “Increasing feed rates from 2.5 to 3kg saw a significant increase in litter size (13.2 to 15.2 piglets) and an increase in piglets born alive (12.6 to 14.3 piglets).” However, farrowing rate was reduced from 90% to 77% from first insemination.

Feed solution vital for getting sows back on track

Feeding glucogenic diets or topdressings may shorten weaning to oestrus intervals and reduce within litter birth weight variation, said Prof Kemp. “Glucose stimulates insulin production, which acts on the ovaries and stimulates follicle growth, thus being beneficial to reproduction.

“Maize starch or dextrose has the potential to stimulate insulin production post-feeding. By feeding a starch-rich diet, there is the potential to increase the number of sows cycling by 15%.”

In a trial comparing two diets – a standard diet of 3.5 kg a day and a standard diet including another 150g dextrose a day – the variation in piglets’ birth weights was lower in sows supplemented with dextrose. But even the slightly smaller piglets from the dextrose-fed sows had lower mortality.

Boar contact post-weaning can also stimulate the onset of oestrus, with the effect being most pronounced in sows with long weaning to oestrus intervals.

“This is probably caused by the effect of boar presence on luteinizing hormone release by the pituitary gland,” Prof Kemp said.

Boar presence coupled with the back pressure test also resulted in 21% more sows ovulating compared to just using the back pressure test in the absence of a male where 30% ovulated.

“To maximise the effect of boar presence, sows should be exposed to males as soon as possible after weaning, two or three times a day,” Prof Kemp said.