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Tryptophan (Trp) plays an important role in piglet growth and regulates the composition of the microbiota in the hindgut. However, it remains unclear how adequate and inadequate dietary Trp impact intestinal microbial ecology. The purpose of this study was to reveal the mechanism of the effects of insufficient, adequate, and excess Trp on the intestinal microflora and growth performance of weaned piglets. A total of 40 28-day weaned piglets were allocated to four groups with 10 barrows per group and one pig per replicate. Piglets were fed a corn and soybean meal-based diet with 0.14% (deficient), 0.21% (adequate), 0.28% (excess), or 0.35% (excess) Trp for four weeks. Growth performance was measured and five piglets from each diet group were euthanized, and blood and tissue samples were collected.
The average daily body weight gain, average daily feed intake, feed conversion ratio, spleen index, pancreas index, longissimus dorsi muscle index, plasma insulin, 5-hydroxytryptamine, kynurenine, and Trp concentrations of weaned piglets increased in a dose-dependent manner. Compared with the 0.14% Trp diet, the adequate-Trp diets (0.21%, 0.28%, or 0.35%) down-regulated the relative abundances of 12 genera including Turicibacter, Prevotella, Mitsuokella, Anaerovibrio, Megasphaera, Succinivibrio, Sutterella, Desulfovibrio, and Methanobrevibacter; up-regulated the abundances of Ruminococcaceae, Lactobacillus, and Muribaculaceae in the colon; and augmented the mRNA level and concentration of porcine β-defensin 2 in the small intestinal mucosa. Moreover, Trp-adequate diets increased the abundances of Trp hydroxylase, indoleamine 2,3-dioxygenase, porcine β-defensin 2, phosphorylated mammalian target of rapamycin, and phosphorylated protein kinase B in the small intestinal mucosa.
It was observed that a corn and soybean meal-based diet with 0.35% Trp may be a nutritional strategy to improve growth performance, intestinal mucosal barrier integrity, and intestinal microbial ecology in weaned piglets.
Rao Z, Li J, Shi B, Zeng Y, Liu Y, Sun Z, Wu L, Sun W, Tang Z. Dietary tryptophan levels impact growth performance and intestinal microbial ecology in weaned piglets via tryptophan metabolites and intestinal antimicrobial peptides. Animals. 2021; 11(3): 817. https://doi.org/10.3390/ani11030817
