Nutritional Immunology in Swine

Abstract Text: The immune system of pigs is vital as its proper functioning protects the pig from disease and health. It also causes inflammation, which contributes to the animal’s ability to fight off infection but also inhibits growth performance by reducing feed intake and diverting amino acids and nutrients away from growth to the immune response. It is now clear that reducing inflammation would benefit for pig health. We have shown that several plant extracts can do just that as shown here. Our in vitro study reported that several plant extracts (anethol, capsicum oleoresin, carvacrol, cinnamaldehyde, eugenol, garlicon, and turmeric oleoresin) suppressed (P < 0.05) pro-inflammatory cytokines’ secretion from lipopolysaccharide-stimulated porcine alveolar macrophages, which indicates the in vitro anti-inflammatory effects of these plant extracts. Results from an in vivo Escherichia coli (E. coli) challenge study showed that feeding capsicum oleoresin, garlicon, or turmeric oleoresin reduced (P < 0.05) diarrhea of E. coli-challenged pigs. Feeding these 3 plant extracts also decreased inflammatory responses of E. coli-challenged pigs, as indicated by reduced (P < 0.05) white blood cell numbers, serum pro-inflammatory cytokines, and acute phase proteins when pigs were fed plant extracts compared with pigs fed control diet. A potential mechanism of action is that plant extracts may enhance gut mucosa health and attenuate the overstimulation of the immune system. The microarray data from the same in vivo study indicated that these plant extracts counteracted (P < 0.05) the effects of E. coli by reducing the expression of genes involved in antigen presentation or other biological processes of immune responses. Another in vivo study was conducted with porcine reproductive and respiratory syndrome virus (PRRSV) challenge. The results of this study indicated that feeding these 3 plant extracts to nursery pigs enhanced the pigs’ immune responses to a PRRSV challenge and may help alleviate negative impacts of infection, as indicated by reducing (P < 0.05) viral load and serum concentrations of inflammatory mediators, and shortening (P< 0.05) the time of fever in PRRSV-infected pigs. In conclusion, feed additives, such as certain plant extracts, may potentially improve pig health and disease resistance by modulating inflammation.

Keywords: immunology, pigs, plant extracts