LOW FISH MEAL DIET ON GROWTH PERFORMANCE, HEPATOPANCREAS-INTESTINAL HEALTH, AND MUSCLE QUALITY OF RED SWAMP CRAYFISH (PROCAMBARUS CLARKII)

In order to reduce feed costs, commercial diets for Procambarus clarkii mostly use high-level plant protein to replace fish meal, resulting in diets containing less than 5% fish meal. This study evaluated the effects of low fish meal diets on the survival, growth, muscle quality, and health of P. clarkii by comparing a control diet with 10% fish meal to an experimental diet with 2% fish meal (replacing fish meal with a 1﹕1 soybean meal–rapeseed meal mixture). P. clarkii with an initial weight of (3.90±0.01) g were used as the experimental subjects, and an 8-week aquaculture experiment was conducted in an indoor circulating water aquaculture system. The results showed that low fish meal diet did not significantly effect the survival rate, growth indicators (including weight gain rate, specific growth rate, intestine-somatic index, hepatopancreatic index, gonadosomatic index, and condition factor), apparent digestibility, digestive enzyme activity, antioxidant capacity, and non-specific immunity of P. clarkii. There is no significant impact on the basic nutritional components or amino acid composition of muscles. Compared with high fish meal feed, low fish meal (2%) diet significantly increased meat yield (P<0.05), increased the muscle content of oleic acid, linoleic acid, alpha linolenic acid, eicosaenoic acid, monounsaturated fatty acids, and n-6 polyunsaturated fatty acids (P<0.05), and reduced cadmium content in the hepatopancreas (P<0.05), thus improving the nutritional quality of crayfish. In addition, low fish meal diet induced morphological changes in hepatopancreas and intestinal tissues, significantly decreasing the relative abundance of Bacteroides vulgatus and increasing iron-reducing bacteria in the intestinal microbiota (P<0.05). Although these changes did not have a negative impact on the survival, growth, digestion, antioxidant levels, or non-specific immunity, they also indicate that low fish meal content in feed may be detrimental to the hepatopancreas and intestinal health of P. clarkii.