Teams around the United States are hard at work trying to decipher why healthy-looking nursery pigs are starving out.

A puzzling pig-wasting problem spreading across the country has researchers and producers alike searching for answers.

About 10 months ago, producers started reporting nursery fallout problems, says Mike Tokach, Extension swine specialist, Kansas State University (KSU). Newly weaned nursery pigs appeared to be eating quite well, then a couple of days later they quit eating.

In affected barns, 2-10% of pigs have either died or wasted away. “They go through a very long-term starvation period and either die or have to be euthanized,” Tokach reports.

KSU swine researcher and graduate student John Bergstrom completed one trial comparing four similar nursery diets to determine if there is a dietary component. The trial showed surprisingly big differences in ingredient quality, sourcing and processing — but so far nothing that proves that diet is playing a role, Tokach reports.

The next trial will evaluate the potential role of porcine circovirus and mycoplasma vaccines in producing feed depression.

“What I think we are going to find is that in this postweaning period there are several factors involved: management issues, feed ingredient quality and possibly timing of Mycoplasmal pneumonia and circovirus vaccines that we weren't as concerned about a couple of years ago,” Tokach says.

Multifactorial Syndrome

At the 2008 Leman Swine Conference in St. Paul, a veterinary team presented a report on Postweaning Catabolic Syndrome.

The team demonstrated this syndrome is a multi-factorial industry problem involving postweaning pigs that fail to thrive. The team consisted of Luc Dufresne, DVM, Seaboard Foods; Thomas Fangman, DVM, Boehringer Ingelheim Vetmedica, Inc., and Steve Henry, DVM, Abilene (KS) Animal Hospital.

Their findings were that normal, well-grown pigs begin a progressive decline in body condition within the first five days after weaning. “Even with early detection and immediate supportive nutrient and antimicrobial intervention, affected pigs catabolize fat and muscle tissue over the ensuing 2-3 weeks and deteriorate to become emaciated and require euthanasia,” they explain. “Catabolize” refers to a metabolic imbalance and release of energy that results in a breakdown of complex materials within the organism.

Kansas Field Observations

In swine veterinarian Henry's experience with client herds, weaned pigs at 3-10 days postweaning, with good frame and condition, suddenly become gaunt and anorexic, yet active and alert. “But (they) progress to thin-as-rails by 14 days postweaning and usually die by 17 days postweaning,” he says.

Field necropsies reveal a breakdown of fat in organs and a depletion of fat reserves in most parts of the body. “The gastrointestinal tract is void of ingested feed, feces are pasty and scant, and many pigs appear not to have eaten since being weaned,” he states.

Henry stresses this “catabolic syndrome” is a feature of the well-conditioned, well-framed pig at weaning. These are pigs typically weaned at 21-24 days of age weighing 13-16 lb., carrying impressive body fat stores and appearing vigorous and active.

Tale of Two Syndromes

Dufresne says the Seaboard production system has stuck with weaning pigs at 16-18 days of age, but clinical signs and necropsy results of “failure to thrive” pigs mimic Henry's observations.

“These animals show severe anorexia/cachexia (general physical wasting and malnutrition) with no apparent infectious agent involvement. The syndrome is observed most often in normal or large piglets.

“What has changed, lately, is the increase in prevalence of the condition,” he says. “The combined results of six, system-wide necropsy audits, performed between March 2003 and May 2006, and involving several thousand pigs, show that failure to thrive was the fourth most important cause of mortality behind pneumonia, polyserositis and colitis.” See Figure 1.

Moving to source-specific necropsy audits, two different patterns of the syndrome emerged, Dufresne adds. One is a high incidence of failure to thrive with a high rate of colitis and pneumonia. (Figure 2). “In these cases, diagnostics implicate salmonella and rotavirus, and we suspect that the failure to thrive was initiated by one or both of these pathogens,” he continues.

The use of vaccination, strategic antibiotic treatment and partial depopulation has greatly reduced mortality in those flows. “Although we have been successful at controlling the pathogens, failure-to-thrive pigs remain, but at much lower levels,” Dufresne counters.

In contrast, a different trend has emerged in the last year in some of Seaboard's production flows. “Necropsy results shown in Figure 3 indicate that failure to thrive is the first- or second-highest cause of mortality with no major lesions of colitis or enteritis,” he asserts. In these cases, the catabolic syndrome seems to play a major role by itself. Dufresne offers three major clinical observations:

  • The severity of the syndrome is sow-farm dependent. When pig sources are combined in the same nursery barn, the prevalence of failure-to-thrive pigs can be four to five times higher in one source vs. the others.

  • Porcine reproductive and respiratory syndrome (PRRS) can be involved, but not always. In one case, when two sow farms combined pigs in nurseries in source-specific rooms, the syndrome results were worse in the offspring coming from a PRRS-stable farm than the offspring from a PRRS-unstable farm.

  • Males are more affected than females. In farms experiencing this syndrome, death loss in barrows is usually twice as high as in gilts. In the necropsy audit results shown in Figure 3, out of 236 piglet necropsies, 152 were barrows and 84 were gilts, Dufresne points out.

Nutritional Considerations

Henry says the inability to obtain whey with predictable quality has led to modifying feed budgets based on wean weight, with less plasma protein included in starter diets.

Henry resolves there are six points impacting nutrition in the current syndrome, based on talks with Tokach:

  • The lactose and lactalbumin in whey are key to predictable response of starter diets. The industry is now using more whey permeate, where the whey protein is removed (used for human markets).

  • Fish meal has also been a critical component in weaned pig diets. The quality and quantity of fish meal has seriously declined, and along with it, the performance of diets in weaned pigs. A number of recent trials show fish meal sources have poorer performance than pigs fed diets with soybean meal replacing the fish meal.

  • Cost-saving moves add to problems. Reducing feed budgets in older, heavier pigs means less plasma and whey to start the pigs.

  • An increase in ingredients in weaning pig diets to improve performance and reduce costs could actually increase quality problems.

  • It can be difficult to identify and solve this syndrome in a normal research setting because it's tough to replicate what's happening in the field. Providing extra care in the research barn to carry out the trial often results in improved performance.

“The greatest frustration is that we have learned much about ingredients to increase consumption, help the immune system, reduce villus atrophy, alter pH, etc., and yet, getting pigs started on feed is a bigger issue today than in years past,” Henry comments.

Health, Treatments

The team agrees that infections with PRRS, swine influenza virus, circovirus, salmonella and rotavirus can certainly compromise the pig, and combined with a lack of feed consumption, lead to a failure to thrive and ultimately death.

The environmental stress of chilling, plus the competition associated with establishing dominance during postweaning, places these challenged nursery pigs more at risk.

Specific efforts to improve pig performance have included hand-feeding pellets, the use of milk products and milk replacer, dextrose/electrolyte preparations and multi-day supplementation with concentrated glucose/glycine solutions. Diets have also been supplemented with nutrient-dense feeds and complex protein and lactose.

The results are sometimes beneficial, but more often confusing. These compromised pigs return to feed consumption, yet fail to grow normally and muscle deposition does not rebound normally, according to the team report. Most of these pigs end up being classified as non-growers and are euthanized prior to the move to finishing.

In conclusion, the veterinary team says the postweaning catabolic syndrome has led to a great deal of speculation, yet little data beyond clinical and pathological evaluations. Neither approach has yielded a greater understanding of the cause, processes or appropriate intervention.