There are many diseases in the pork industry that are invasive, as well as expensive for producers. When looking on a global scale one of the most intrusive and invasive diseases is porcine reproductive and respiratory syndrome (PRRS). Even though PRRS is not occurring on every farm, it is still one of the biggest disease problems in the swine industry.

E. coli has also been a problem historically and continues to be on an industry-wide basis, said James Pettigrew, a researcher with the University of Illinois. Either one of the diseases can sweep through a farm so their alleviation would substantially reduce production costs. Although, many management practices have been used in the swine industry, these practices can’t guarantee freedom from disease for pigs, he said.

Consumer concerns about bacterial resistance to antibiotics have prompted the swine industry to seek additional methods to protect the health of pigs, including special feed additives. This interest led Pettigrew and his team to explore the potential benefits of selected plant extracts

The researchers conducted two experiments to test the beneficial effects of adding plant extracts to pig diets to combat PRRS and E. coli. In both experiments, researchers used four diets in weanling pigs, including a control diet and three additional diets that included garlic botanical extracted from garlic, turmeric oleoresin extracted from ginger, or capsicum oleoresin from pepper. In both experiments, half of the pigs in each dietary treatment were challenged with either E. coli or PRRS virus while the other half of the pigs were non-challenged.

It’s been known for a long time that plant extracts, also called essential oils or botanicals have certain biological actions, mentioned Yanhong Liu, a doctoral student who led the studies.

Liu noted that the oils can act as antioxidants or as antimicrobials, so her research team wanted to test whether or not individuals could get a benefit from feeding those products in very low doses to pigs that may be challenged with specific diseases, such as PRRS and E. coli.

E. coli, a bacterial illness of the gut, is marked by diarrhea, decrease in appetite, decrease in body weight, and in some cases, a higher mortality rate. E. coli is especially dangerous post-weaning as pigs adapt to new feed and new environments, Pettigrew said.

The pigs in the study challenged with E. coli that had been fed any of the three plant extracts had a lower frequency of diarrhea (20 percent) than the pigs fed the control diet (40 percent). The pigs fed plant extracts were more efficient (40 percent) in feed use than the pigs fed the control diet in the E. coli-challenged group, and challenged pigs fed plant extracts had sounder gut morphology compared with the challenged pigs fed the control diet.

 

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Liu noted that even the pigs in the non-challenged group, with a low frequency of mild diarrhea, benefited from the plant extracts. Typically, there is a relatively high diarrhea rate in post-weaning pigs when they are moved from their mom and started on all solid feed, she mentioned that the extracts could also be used to help reduce this occurance.

Common symptoms of PRRS, a viral infection of the lung, include fever, lethargy, trouble breathing, loss of appetite, and decreased growth performance. The disease can also lead to spontaneous abortions and higher pre-weaning mortality rates in pigs.

After feeding the pigs challenged with the PRRS virus the three plant extracts, the researchers observed that the pigs were more efficient in week 1 (55 percent) and week 2 (40 percent) than the pigs fed the control diet. The pigs continued eating and gaining weight. They found this to be especially true with turmeric, Liu said.

When they checked blood samples from the pigs with the PRRS virus, they found that the pigs fed plant extracts also had a lower blood viral load (13 percent) and lower concentrations of inflammatory mediators than pigs fed the control diet. These observations also suggest that feeding plant extracts could suppress ongoing inflammation and prevent secondary infections.

The researchers believe the benefits resulted from the effects on the pigs’ immune systems because feeding plant extracts reduced the inflammation caused by E. coli and the PRRS virus.

When dealing with production animals, inflammation is quite costly, because inflammation reduces feed intake, and it diverts nutrients away from growth to the animal’s immune system, Pettigrew said.

If the aide of the extract can help bring the inflammation back down to normal quickly, than it helps can bring that quickly than that helps in production.

Although previous studies have looked at using plant extracts in pig diets, Pettigrew said Liu’s study, which looked at the effects of three different extracts on two different diseases, had not been done previously. He also added that the low concentration of the extracts used while still producing beneficial results set this study apart.

The researchers will continue to study the mechanisms behind the beneficial effects they observed, including conducting gene expression studies. They are looking to see the big picture Liu said, including how the plant extracts affected the challenged and non-challenged pigs.

“Dietary plant extracts alleviate diarrhea and alter immune responses of weaned pigs experimentally infected with a pathogenic Escherichia coli” was published in the November 2013 issue of Journal of Animal Science and can be accessed online at http://www.journalofanimalscience.org/content/91/11/5294.full. Co-authors of the study were Liu, Pettigrew, M. Song, M. Che, J.A.S. Almeida, J.J. Lee, D. Bravo, and C.W. Maddox.

“Dietary plant extracts improve immune responses and growth efficiency of pigs experimentally infected with porcine reproductive and respiratory syndrome virus” was published in the December 2013 issue of Journal of Animal Science and can be accessed online at http://www.journalofanimalscience.org/content/91/12/5668.full. Co-authors of the study were Liu, Pettigrew, T.M. Che, M. Song, J.J. Lee, J.A.S. Almeida, D. Bravo, and W.G. Van Alstine.

Pancosma SA, Geneva, Switzerland, provided funding for the research.

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