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Crossfostering: Less Is More

Article-Crossfostering: Less Is More

Reducing tried-and-true practice saves more baby pigs.North Carolina pork producer Mike Chase was at his wit's end. He thought he was doing a good job of following the McRebel system of reduced crossfostering, and still he was filling a pickup truck weekly with dead pigs from PRRS (Porcine Reproductive and Respiratory Syndrome).Preweaning mortality was running 15-21%, with nursery mortality alone

Reducing tried-and-true practice saves more baby pigs.

North Carolina pork producer Mike Chase was at his wit's end. He thought he was doing a good job of following the McRebel system of reduced crossfostering, and still he was filling a pickup truck weekly with dead pigs from PRRS (Porcine Reproductive and Respiratory Syndrome).

Preweaning mortality was running 15-21%, with nursery mortality alone spiking to 6%. There were also some late-term abortions and early farrowings.

The Snow Hill, NC, producer saw productivity sinking as he became disenchanted with McRebel as he was using it.

McRebel (Management Changes to Reduce Exposure to Bacteria to Eliminate Losses) was developed in 1994 by Monte McCaw, DVM, North Carolina State University (NCSU). It calls for limiting crossfostering in the face of PRRS to the first 24 hours after farrowing. There are only two exceptions: when a sow is sick or dies and when the sow's udder is breaking down or dries up and the piglets need to be moved to a functioning teat.

When McCaw made his way to the 1,800-sow, farrow-to-feeder pig contract production unit managed by Chase for owner Joel Harrison, McCaw expected a cold reception from Chase. He knew Chase had been meticulous about limiting crossfostering, providing extra care for poor-doing pigs in the nursery and doing a top-notch job of sanitizing and disinfecting the eight farrowing rooms and seven nursery rooms operated strictly all-in, all-out (AIAO). The crossfostering protocol was started in January 1997 to try and control greasy pig disease.

System Flaw But when McCaw went to the Chase farm, he found an unexpected flaw in how Chase was using the McRebel system, which was now being expected to ward off an outbreak of PRRS. Crossfostering was indeed only being performed within 24 hours of birth. However, in sizing and sexing all litters at birth, more than 85% of piglets were being raised by a foster dam, meaning less than 15% of piglets were raised by their natural mothers, observes McCaw.

At the time of the McCaw visit, two months after the initial outbreak of PRRS, Chase agreed to change his approach to fully implement McRebel. He agreed to only crossfoster as few baby pigs as possible onto sows that had available functioning teats. Less than 15% of piglets were being moved between litters in the farrowing room. Normal practices of sorting by size and sexing of litters were disregarded when making fostering decisions, explains McCaw. Piglets were only fostered to other litters within the same farrowing room.

McCaw also made Chase get tough on marginal piglets. Those that did not respond to 5-6 days of antibiotic treatment or became thin or lethargic were euthanized. Thin, long-haired, gaunt and depressed pigs at weaning were also euthanized. All euthanasias counted as a mortality against their sow.

At weaning, pigs from two farrowing rooms were sorted by size and sex regardless of litter of origin and placed in a single nursery room.

Small, but apparently healthy (not gaunt) pigs were moved to the nursery and received special care such as easy access to water, heat lamps, pre-starter pelleted feed and broad-spectrum antibiotics as needed. This gave them a chance to grow without excessive stress at weaning, says McCaw.

McCaw explains that two to four pens per nursery room (total of 40 pens/room) were reserved for sick pigs for antibiotic therapy and reduced competition. Those that remained lightweights or sick by feeder pig sale time were euthanized rather than held back.

Performance Improves Within a short time of implementing the full McRebel management program to fight PRRS, preweaning mortality dropped to less than 10%, and nursery culls and mortality dropped to 3%. Feeder pigs were getting on the truck at 9-9.5 weeks of age weighing over 48 lb., on average, says McCaw. Combined preweaning mortality, nursery mortality and culls stayed under 12.5% throughout the 30-week study McRebel was observed. See Table 1 on page 38.

"These improvements in performance were achieved despite continued, clinical PRRS manifested as early farrowings, weak-born piglets and elevated numbers of mummified fetuses during the subsequent nine weeks after implementation of McRebel," he says.

In fact, the virus was still circulating in the nurseries 12-16 weeks after McRebel was started, during which nursery mortality and culls were held to only 3%, says McCaw.

"Those 7-to-10-day-old piglets weren't much to look at, but they were alive and I was taking that," Chase recalls. "By the time they were weaned at 18 to 21 days, they actually looked pretty decent."

Sure those disease-affected piglets were a little light at market time, but Chase still has been able to sell feeder pigs at record weights. "His average used to be 44-46 lb. pigs. Now he's selling 50-54 lb. feeder pigs regularly," McCaw says.

At the time, those old selling weights looked fairly good, but too many were dying, Chase admits.

"We didn't know we were spreading around disease because we thought since we were crossfostering within the first 24 hours, we would be okay," he says. "But with the massive movement of pigs we would do, a sow might not get a single pig that she farrowed, which we found out was very bad, spread disease further and created more problems."

McRebel: More For Less The beauty of McRebel is that it has successfully been used in herds with endemic PRRS and in those apparently not helped by vaccine or other management programs, notes McCaw. It costs very little. It reduces labor, providing more time for sow management and nursery pig care.

"We are working less and we've got better pigs," Chase beams. "Sometimes we used to spend most of the day crossfostering baby pigs." Since McRebel, a staff person quit and a replacement was not hired. Still, all the work gets done, he says.

McCaw cites three reasons McRebel works to improve farrowing/nursery pig performance even while virus is circulating in thesow herd:

1. Researchers in several attempts at Iowa State University have shown that most field strains of PRRS in themselves don't kill pigs.

2. Piglets are born essentially bacterial disease free.

3. The majority of clinical signs and mortality associated with field cases of PRRS is a result of secondary bacterial infections.

The goal of severely limiting crossfostering to the 24-hour "rule" was devised "as a compromise between the desire to not move piglets among litters to limit spread of bacterial pathogens during PRRS outbreaks and the need of producers to use all sows' functional teats available," McCaw explains.

That's also the first rule of McRebel, to severely limit crossfostering.

Second, piglets should not be moved between different rooms to "nurse sows" (especially poor-doing or possibly diseased piglets to younger age groups attempting to save them).

Third, very sick, debilitated pigs that are non-responsive to therapy should be euthanized immediately.

Fourth, weaned and nursery pigs should only be moved AIAO, by room.

"The paradox in all of this is that the smaller the pigs are, the more likely they are to get moved, and the more they get moved, the more they are likely to end up being gaunt, poor-doing pigs," observes McCaw.

In fact, the reverse would be a better course of health management, he says. That means crossfostering the larger, healthier piglets. He points out that Dutch research indicates it's better not to have a litter or pen of all dominant or all submissive pigs because they do not perform well.

The goal of limiting crossfostering started out as a way simply to save pigs and create healthy pigs, says McCaw. But what has happened is that we've ended up keeping small pigs and big pigs in the same litter, probably creating the perfect pecking order.

The second, more surprising point is that most of these smaller pigs are simply that. They are smaller but not necessarily runts.

"Those small pigs can have great body condition at weaning, even when they've had to live in litters with larger brothers and sisters," McCaw says. "There's the really exciting thing about McRebel. It's the realization that baby pigs' body condition can be excellent across all sizes of pigs in the same litter, as long as each pig gets a functional teat to suckle.

"The limiting factor is not the amount of competition between the pigs, because that competition ends the first or second day when they have assigned themselves teats. The social order is decided," he adds.

The limiting factor, surmises McCaw, is man. By frequent crossfostering piglets in order to create equality in the litter, man is actually forcing piglets to fight again and again, miss meals and possibly spread disease.

Crossfostering is a long-standing management practice in the pork industry, he admits.

But by altering the practice, producers may finally have found a cheap way to reduce preweaning and nursery death losses initiated by PRRS virus.

Crossfostering is a good management practice that is abused on many farms," says Rick Tubbs, DVM, Green River Swine Consultation, Bowling Green, KY.

In order for the practice to be beneficial, colostral intake must be insured. Then the transfer of pigs should occur as soon as possible after farrowing, he says.

"I recommend that litters be evened out by transferring the larger pigs in a litter. They seem to compete better within a new litter."

Tubbs believes that creating a "runt" or "nurse" sow for the smaller pigs within a farrowing room may be a good idea.

But be sure to avoid "fostering disease," where the poor-doing pigs are transferred almost compulsively from sow to sow, he stresses. "This practice is not beneficial to the transferred pigs, and in the case of diseases such as PRRS (Porcine Reproductive and Respiratory Syndrome), these pigs may serve as a means of spreading the virus throughout all the litters in a room," he says.

Plus, manage the needs of the piglets the first three days of life, and in most cases, you will have preweaning mortality under control. That means make sure that piglets receive small meals from the sow every 1 to 2 hours (first colostrum should be within 12 hours of birth). The also should have a warm, draft-free environment with a temperature of about 86 "degrees" to 93 "degrees" F.