Antimicrobial effect of dietary nitrate in weaning piglets challenged or not with Salmonella enterica serovar typhimurium

Summary

The maintenance of a beneficial bacteria balance in the gut is important to increase the animal’s resistance to diseases. Nitrite may kill gut pathogens representing a non-immune defence mechanism. Nitrite can be derived from dietary nitrate that is reduced under the acidic conditions of the oral cavity.
An in vivo study was designed in order to establish the antimicrobial effects of dietary nitrate on the gut microbiota and on the health of 96 weaning piglets. The pigs were fed a diet containing high levels of nitrate (15 mg/kg feed and 150 mg/kg feed) and then challenged with Salmonella enterica serovar typhimurium. Changes of the intestinal microbiota composition were assessed by analysing the stomach and jejunum contents from all the pigs.
Results showed that nitrate only affected the population levels of Lactic Acid Bacteria (LAB) in both segments. Pigs challenged with Salmonella showed a reduction in the levels of E. coli and clostridia in the jejunum suggesting a mechanism of competition for niches or for active sites. The time from challenge significantly decreased the number of LAB in stomach and jejunum. It also decreased the population density of clostridia in the stomach. The supplementation of feedstuff with high dietary nitrate intake contemporarily to the challenge with Salmonella did not affect the degree of ulceration in the pigs.