Gastrointestinal health and function in weaned pigs: The role of low dietary crude protein

Post weaning diarrhea (PWD) is a major global threat to the swine industry and this disease has been managed in the past by supplementing starter diets with subtherapeutic levels of antibiotics. With the ban of in-feed antibiotics in the European Union and increasing interest to eliminate their usage in livestock diets around the world, the swine industry faces a major challenge of finding effective alternatives to in-feed antibiotics. A series of experiments were conducted to determine the effectiveness of low crude protein (CP), amino acid (AA)-supplemented diets as a nutritional strategy of enhancing gut health and mitigating PWD in piglets. The first experiment investigated the performance and gut health benefits of feeding low CP, AA-supplemented diets to piglets. Low CP diets reduced ammonia N concentration in cecal digesta, small intestine weight and crypt hypertrophy in piglets compared with the high CP diet. In the second experiment, the effect of dietary CP level on performance, immunological response and gut ecology of weaned pigs challenged with enterotoxigenic Escherichia coli (ETEC) K88 was evaluated. Compared with the high CP diet, the low CP diet reduced the impact of ETEC infection on growth performance, minimized the incidence of diarrhea, reduced ETEC count in the luminal content of the small and large intestine, increased the prevalence of butyrate producing bacteria in colonic digesta and protected against inflammatory-associated responses induced by ETEC. The third experiment was conducted to determine the effects of dietary CP level on intestinal development. The low CP diet did not impair jejunal brush border enzyme development of weaned pigs. The fourth experiment determined the effect of dietary CP level on intestinal response of piglet to ETEC K88 infection. The high CP diet increased the number of adherent ETEC and the expression of sodium-coupled glucose transporter 1 in jejunum of piglets compared with the low CP diet. Overall, the results demonstrated that low CP diets supplemented with crystalline AA according to the ideal protein pattern could be used as a dietary tool for enhancing gastrointestinal health and function in piglets. In addition, the results revealed evidence of novel mechanisms underlying gut health benefits associated with feeding low CP diets supplemented with AA to piglets.;...