Dietary taurine impairs intestinal growth and mucosal structure of broiler chickens by increasing toxic bile acid concentrations in the intestine

Three experiments were conducted to determine the effect of taurine on the intestinal development, bile acid concentrations, and hormonal status of chickens. In experiment 1, a total of 250 one-day-old broilers were randomly allocated to 5 treatments and supplemented with 0, 0.25, 0.50, 1.00, and 2.00 g/kg of taurine, respectively. Growth performance, weight and length of the small intestine, and intestinal morphology were measured on d 7, 22, and 44. The gene expression levels of several hormones, including epidermal growth factor and cholecystokinin, were also evaluated. In experiment 2, 60 one-day-old broilers were supplemented with 0, 1.0, and 5.0 g/kg of taurine to assess cell proliferation in the jenunal crypt. In experiment 3, 100 newly hatched broilers were assigned randomly to 5 treatments (0, 0.10, 0.50, 2.00, 8.00 g/kg of taurine) to evaluate the bile acid concentrations in the jejunal mucosa. Our results indicated that dietary taurine decreased the length and weight of small intestine, the villus width, surface area, and crypt depth in the duodenum and jejunum (P < 0.05). Taurine also increased the expression of cholecystokinin and epidermal growth factor on the jejunal mucosa (P < 0.001). Taurine has little effect on stimulating the proliferation of intestinal crypt cells, except for 5 g/kg of taurine supplementation on d 14 (P < 0.05). Additionally, a linear increase in the jejunal concentrations of taurocholic acid, taurochenodeoxycholic acid, and taurolithocholic acid was observed on d 7 in broilers fed increasing levels of taurine. In conclusion, we suggested that taurine impairs intestinal mucosal development partly through generation of toxic bile acids.