Effect of β-Alanine Metabolite on Gut Integrity and Immunity in Commercial Broiler Chickens Infected with Eimeria maxima

(1) Background: In a metabolomics analysis conducted to investigate the mechanisms behind the growth-promoting effects of probiotics in broilers, β-alanine was found to be significantly elevated. This led to the hypothesis that β-alanine could also contribute to growth-promoting effects in infected broilers. (2) Methods: An in vitro culture system was developed to assess β-alanine's impact on proinflammatory cytokine response in chicken macrophage cells, gut integrity in chicken intestinal epithelial cells, and muscle differentiation in quail muscle cells and primary chicken embryonic muscle cells. In vivo animal feeding studies were then conducted to investigate the effects of dietary β-alanine on various disease parameters in <i>Eimeria maxima</i>-infected broiler chickens. (3) Results: In vitro, β-alanine treatment significantly decreased the gene expression of cytokines in chicken macrophage cells and increased occuldin expression in chicken intestinal epithelial cells. Dietary β-alanine increased the body weight of chickens following <i>Eimeria maxima</i> infection in the H-ALA group. Dietary β-alanine also suppressed cytokines and increased JAM-2 and occludin expression in the H-ALA group compared to the infected group without β-alanine supplementation. (4) Conclusions: These results strongly support the positive effects of dietary β-alanine on intestinal immune responses and gut barrier function in broiler chickens infected with <i>Eimeria maxima</i>.