Improvement of growth, intestinal short-chain fatty acids, non-specific immunity and ammonia resistance in Pacific white shrimp (Litopenaeus vannamei) fed dietary water-soluble chitosan and mixed probiotics

This study was to explore the impacts of water-soluble chitosan and mixed probiotics on growth performance, intestinal short-chain fatty acids (SCFAs) and immunity and ammonia resistance in Litopenaeus vannamei. Shrimp were fed one of four experimental diets including basal diet (CON), 0.10% water-soluble chitosan diet (WSC), 0.30% mixed probiotics (MP) and 0.10% water-soluble chitosan +0.30% mixed probiotics (SYN) for 8 weeks. Results showed shrimp fed with dietary MP and SYN diets could significantly improve growth performance and feed utilization in comparison with those of shrimp fed with CON diet (P < 0.05). Acetic acid content was significantly higher in shrimp fed with all supplemented diets compared to that in shrimp fed with CON diet (P < 0.05). Compared to shrimp fed with CON diet, dietary WSC and MP significantly influenced the contents and/or activities of aspartate aminotransferase (AST), total protein (TP), superoxide dismutase (SOD), lysozyme (LZM) in serum, SOD, malondialdehyde (MDA), acid phosphatase (ACP) in hepatopancreas and SOD and MDA in intestine. In addition, the gene expression levels of prophenoloxidase (proPO), penaiedin 3a (Pen-3a), crustin (Crustin), serine proteinase (SP), GPX and SOD in hepatopancreas, were significantly upregulated compared to those in CON diet at some time points (P < 0.05). Significantly higher survival rate in all supplemented diets were observed after ammonia challenge (P < 0.05). Therefore, the above results indicated dietary WSC and MP or SYN could enhance intestinal SCFAs content, stimulated antioxidant capacity and immune responsdde, and increase the ammonia resistance of Litopenaeus vannamei. Besides, the growth performance was also improved by dietary MP and SYN.