How to get the best returns from big litters

Sunday, April 5, 2015

Cross-fostering is one approach, but it has its shortcomings. An Ontario Pork research project is looking at effective ways to feed baby pigs milk replacer

by DON STONEMAN

Geneticist Laurence Maignel's January PowerPoint presentation to producers at the Centralia swine update meeting in Kirkton included a drawing of a sow with 20 teats, mothering 20 piglets.

That bit of whimsy – it was a drawing after all – points to where the Canadian Centre for Swine Improvement (CCSI) hopes its breeding efforts are taking it. The number of functional teats is now included in the national dam line index used to select purebred breeding stock, as are piglet perinatal survival and farrowing intervals.

Indeed, pig selection programs around the world are aimed at increasing prolificacy, and the top producers in Denmark, leaders in pork production, are aiming at the dizzying number of 40 pigs per sow per year. With current prolificacy genetics and solid breeding protocols, many sows in Ontario barns today can farrow 18 piglets at once, but most sows still only have 12 working teats to feed them. The gap isn't narrowing any time soon. How can producers themselves translate large numbers of piglets born alive to a high number of pigs weaned?

Cross-fostering is one answer. Babies from one sow with too many for her teats are moved to another sow with more teats than piglets. (See "What is known about cross fostering," page 10.)

But the cross-fostering management technique remains controversial. Cross-fostering has its shortcomings, notes Dr. Tim Blackwell, a veterinarian with the Ontario Ministry of Agriculture, Food and Rural Affairs. Fostering is difficult in smaller operations where relatively few sows farrow at the same time and odds are against one of them having open nipples when extra piglets on another sow need them. And there is the risk of spreading disease. "With PEDv and PRRS, you don't want a lot of cross-fostering going on," Blackwell adds.

Still, the high market demand for pigs makes the extra effort and cost of raising marginal piglets to market weight at a higher-than-herd-average cost worthwhile, and it's a good time to learn how to maximize returns with highly prolific sows. Pigs on milk replacer might not grow as well as pigs suckling their mothers and might wean a kilogram lighter. And, down the road, those pigs will perhaps eat an extra week's feed before they reach market weight. But Blackwell argues that, in this current market, operators will still make money getting these pigs to market.

To that end, Blackwell is co-ordinating a research project funded by Ontario Pork that aims to find an effective and efficient way to feed baby pigs milk replacer. Jean Howden, research and project co-ordinator at Ontario Pork, the project funder, reports that "the overarching intent of this research trial is to capitalize on the improvement in live-born litter size resulting from genetic improvements created by the breeding stock industry. Selection for greater live-born pigs has outpaced selection for increased numbers of mammary glands and pre-weaning mortality has increased on many farms.

"This represents a lost opportunity to profit from the greater number of pigs born alive. Higher pre-weaning mortality is associated with decreased animal welfare, and malnourished pigs are at greater risk of infectious disease, requiring increased use of antimicrobials on farm."

A pilot project last year with four producers had mixed results, Blackwell says. A prototype milk replacer feeder was a failure, but the producers who used it told him the pigs "loved" the milk replacer and thrived on it, with high palatability and no scours.

Blackwell says useful numbers on increasing piglets' survival rate were lacking because each producer worked out a different way of feeding the pigs to keep them alive. Blackwell says producers were enthusiastic about finding ways to save the pigs.

Blackwell is looking for a cheap and easy way to get that milk replacer into the piglets, perhaps with a feeder that goes from crate to crate, or from farrowing to weaner room if some pigs have to be weaned at a light weight.

The change in prolificacy may necessitate changes in any producer's system. Agricultural engineer Franklin Kains notes that producers may have to expand their weaner and finishing facilities as more pigs come from prolific sows. If that isn't possible, maybe an operator will farrow fewer sows. One way or another, Kains says, it will lead to a change in the industry. BP

What is known about cross-fostering
Cross-fostering should only be done to ensure that all pigs have a nipple, stresses Ontario Veterinary College professor Cate Dewey.

If there are too many pigs for the number of available nipples, the pigs can be supplemented with electrolytes, milk replacer and creep feed "but I would keep them in the crate with the sow and do it there, so each pig still has a chance to get milk. Milk antibodies are important to prevent baby pig diarrhea due to E coli."

Pigs need their own nipple, so the idea is to foster the largest pigs from a large litter onto a sow with a smaller litter and free nipples. Pigs should be allowed to get a full stomach of colostrum before they are fostered.

Only the largest pigs in the litter should be fostered off their birth mother, notes Dewey, because research shows they are disadvantaged when taken from their mothers. They will have a lower weaning weight compared to other pigs of the same size at the start. In addition, cross-fostered pigs have a higher mortality rate. This may be because it takes them a while to identify with the new mother they have been crated with.

"When their birth mother begins to grunt to call her pigs to nurse, you can see the fostered pigs trying to get out of their new farrowing crate to get to their birth mother," Dewey says.

After a few days, the pigs will have identified their own nipple, but first the pigs that are fostered will have to fight with the new litter mates for ownership of their nipple on the new sow. BP

Extra care for piglets reduces mortality, helps weight gain
In 2007, Ontario Veterinary College (OVC) researcher Cate Dewey oversaw a project on a commercial 600-sow, farrow-to-finish farm aiming to increase weaned piglet weights and decrease mortality by increasing care for piglets, feeding electrolytes, cross-fostering and timing of processing – all techniques that were reasonable in a commercial setting. The project resulted in reduced mortality in pigs born weighing less than 1.1 kilograms, and all pigs receiving extra care, regardless of their birth weight, were substantially heavier at 16 days of age.

There were four farrowing rooms with four rows of six farrowing crates per room. In each room, two rows received special treatment while the other two received standard treatment. There were 1,367 piglets involved over two cycles of farrowings. Sixty litters bearing 647 piglets alive received standard care, while 66 litters with 720 pigs born alive received maximal care.

Most pigs in both groups (with the exception of small and weak pigs that weren't treated until day three) were processed within 24 hours of birth. Teeth and tails were clipped and piglets received one millilitre of iron. Pairs of sows were used for fostering to establish even-sized litters, with the largest pigs being moved to the foster sows.

At 10 days of age, all pigs received a second iron shot and males were castrated. Sows ate four kilograms of feed twice daily and sows considered by the producer to be thin were additionally fed two-thirds of a cup of soybean oil on one of the meals.

When litters receiving what Dewey calls "maximal care" were processed, instruments were dipped in Dettol between pigs, and both tail and castration wounds and the umbilical area were sprayed with dilute iodine. All the maximal care pigs had access to electrolyte solution from baby pig water jugs and milk replacer bottles.

In addition, maximal care newborns were able to lie on a rubber mat under the heat lamp for three days. Chilled piglets were dried with a towel, given an oral solution of glucose and/or colostrum stripped from a farrowing sow. Splay-legged pigs were taped, massaged and helped to get colostrum. Workers removed sow manure twice a day and sows on the maximal care program received a third meal every evening – 1.2 kilograms at birthing, increased to 1.5, 1.9, and 2.4 kilograms of feed on days five, 10 and 15 after farrowing.

According to a summary of Dewey's published work, pre-weaning mortality overall was 9.9 per cent. None of the piglets weighing less than 600 grams when born could be saved, but losses of 700- to 900-gram pigs receiving maximal care were reduced to 30 per cent from 49 per cent in the standard care group.

At 16 days of age, maximal care pigs weighed an average 4.91 kilograms compared to 4.75 kilograms in the standard group, gaining an average of 3.5 kilograms from birth compared to 3.35 kilograms. The increased weight gain was seen across all weights of pigs, Dewey notes. The result was that pigs weighing less than a kilogram at birth were only half as likely to die in the maximal care as in the standard care crates.

In her study, Dewey notes that the maximal care protocol requires more attention to detail and is time-consuming. On average, the technician spent 18 minutes more per litter over the 16 days of the study for the maximal-care litters than for the standard care litters. That is nearly an additional 20 hours caring for 66 litters and 720 pigs born alive. Most of that time was devoted to cleaning and refilling the electrolyte containers.

Dewey recommends that barn managers determine how much time is spent on each task and determine whether the time required reflects the importance of the task. She suggested that part-time staff be hired to do other jobs and give room workers more time to pay attention to details.

"The decision to adopt these techniques will depend on a balance between the cost of labour and the value of increasing survivability and weaning weights," according to the study that was published in the Canadian Journal of Veterinary Research in 2008.

Dewey notes that these piglets received electrolytes, not milk replacer. "We did not want to reduce the interest of the piglets in the sows' milk."

The study also looked at the survivability of piglets born in the cooler dry sow barn. Once they were moved to the farrowing room, half of those died under standard care, while only 10 per cent died under maximal care. BP