Diet Supplements May Boost Pig Immunity

Feeding pigs mannan oligosaccharides helped combat porcine reproductive and respiratory syndrome virus, a study shows.

by Dani Yokhna
Adult pigs and piglets in barnyard
Courtesy Jupiterimages/Bananastock/ Thinkstock
Feeding pigs a diet with mannan oligosaccharides could help regulate the animals’ immune response to diseases.

A new study at the University of Illinois suggests that feeding pigs mannan oligosaccharides, common nutritional supplements found in livestock feed, can fine-tune their immune systems.

“When it comes to keeping pigs healthy, there are some potentially powerful tools we can use in the diet besides antibiotics,” says James Pettigrew, professor of animal science at UI. “We have a tendency to think that we can administer health through a needle, by giving pigs antibiotics, and even through systems like all-in/all-out pig flow. These are important, but there are also many health benefits we can realize through the diet.”

MOS is a product made from the cell wall of yeast. It contains carbohydrates that might provide special benefits to pigs, Pettigrew says. Previous research shows that MOS increased the growth rates in newly weaned pigs and changed the microbial populations in pigs’ digestive tracts.

Tung Che, a postdoctoral research associate in Pettigrew’s laboratory, led two studies looking at MOS and its effect on pigs experimentally infected with porcine reproductive and respiratory syndrome virus.

In these studies, researchers evaluated how feeding MOS can regulate immune responses in pigs infected with PRRSV.

“We found MOS can enhance immune responses in pigs, but it can also alleviate the overstimulation of the immune system,” Che says. “MOS increases the total number of immune cells, such as leukocytes and lymphocytes, in the blood at the early stage of infection.”

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This could be quite a benefit for pork producers fighting PRRSV, a respiratory disease that causes a reduction of immune cells.

“This is important because the increase in leukocytes and lymphocytes can help the animal to fight not only PRRSV but also secondary bacterial co-infections that are common with PRRSV,” Che says.

Seven days after the PRRSV inoculation, pigs experienced reduced fevers and had a better feed efficiency, indicating a reduction of ongoing inflammation.

“We wanted to find out why MOS enhances the immune system but at the same time alleviates the overstimulation of the immune system as observed by reduced fever,” Che says.

The results were consistent with the clinical signs and showed that in non-challenged pigs, MOS increased the expression of genes for cell receptors and those involved in immunity.

However, in the PRRSV-infected pigs, MOS reduced the expression of cytokine and chemokine genes involved in inflammatory responses. This combination of responses explains the enhanced immune response and the reduction of fever, Che says.

“MOS stimulates the immune system and enhances the immune response, except when the immune system is already challenged,” Pettigrew explains. “MOS actually reduces the inflammatory response in pigs with challenged immune systems. This may be how the product improves growth performance because it redirects nutrients to growth rather than the immune system.”

Che says MOS also improves pigs’ feed efficiency from day seven to day 14 after inoculation with PRRSV.

“PRRSV interferes with the immune response and makes pigs more susceptible to bacterial infections,” Pettigrew says. “This product seems to counteract this effect. It may even reduce bacterial infections associated with PRRSV, although we did not test that specifically.”

The research team is repeating this experiment with a second generation of MOS-like products to learn more about how this mechanism in MOS works.

“We are increasingly concerned about the importance of keeping pigs healthy, so we direct much of our research program to looking at things we can do in the diet to improve the health of pigs,” Pettigrew says.

“Mannan oligosaccharide modulates gene expression profile in pigs experimentally infected with porcine reproductive and respiratory syndrome virus” and “Mannan oligosaccharide improves immune responses and growth efficiency of nursery pigs experimentally infected with porcine reproductive and respiratory syndrome virus” were both published in the Journal of Animal Science. 

Researchers involved in the study include Tung Che, Rod Johnson, Keith Kelley and James Pettigrew of the University of Illinois; Bill Van Alstine of the Animal Disease and Diagnostic Laboratory at Purdue University; and Karl Dawson and Colm Moran of Alltech. Funding was provided by Alltech.

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