Effects of the Replacement of Dietary Fish Meal with Poultry By-Product Meal on Growth and Intestinal Health of Chinese Soft-Shelled Turtle (Pelodiscus sinensis)

SIMPLE SUMMARY: Fish meal is widely used in aquaculture feed due to its high protein content, balanced amino acid composition, and low anti-nutritional factors. However, with the development of intensive aquaculture, fish meal resources are in short supply and prices are rising. In order to ensure the sustainable development of aquaculture, it is very important to find a low-cost, high-quality protein source to replace fish meal. In this study, substituting fish meal of Chinese soft-shelled turtle (Pelodiscus sinensis) diets with poultry by-product meal was carried out. The results showed that replacing fish meal with 15% poultry by-product meal had no adverse effect on the growth of Chinese soft-shelled turtle (Pelodiscus sinensis), and the 10% poultry by-product meal was beneficial to the growth performance, immunity, and digestive ability. Therefore, it is feasible to use poultry by-product meal as a protein source to replace fish meal in Chinese soft-shelled turtle (Pelodiscus sinensis) feed. ABSTRACT: To investigate the effect of poultry by-product meal (PBM) replacing fish meal on the growth and intestinal health of Chinese soft-shelled turtle (Pelodiscus sinensis). Four experimental diets were prepared. Fish meal was replaced by 0 (control group, PBM0), 5% (PBM5), 10% (PBM10), and 15% (PBM15) PBM. Compared to the control group, final body weight, weight gain, and specific growth rate were significantly increased, while feed conversion rate decreased significantly in the PBM10 group (p < 0.05). The PBM15 group significantly increased the moisture content and significantly decreased the ash content of the turtles (p < 0.05). The PBM5 and PBM15 groups significantly decreased the whole-body crude lipid (p < 0.05). The serum glucose content increased significantly in the PBM10 group (p < 0.05). The liver malonaldehyde content significantly decreased in the PBM5 group and in the PBM10 group (p < 0.05). Liver glutamic-oxalacetic transaminase and intestinal pepsin activity were increased significantly in the PBM15 group (p < 0.05). The expression of the intestinal interleukin 10 (IL-10) gene was significantly down-regulated in the PBM10 group and the PBM15 group (p < 0.05), the expression of the intestinal interferon-γ (IFN-γ), interleukin-8 (IL-8), and liver toll-like receptor 4 (TLR4) and toll-like receptor 5 (TLR5) genes were significantly up-regulated in the PBM5 group (p < 0.05). In summary, poultry by-product meal can be used as a protein source to replace fish meal in turtle feed. Based on quadratic regression analysis, the optimal replacement ratio is 7.39%.