Effects of protease supplementation in low fish meal pelleted and extruded diets on growth, nutrient retention and digestibility of gibel carp, Carassius auratus gibelio

• Published in: Aquaculture 2016-07, Vol.460, p.37-44
• Main Authors: Shi, Ze, Li, Xiao-Qin, Chowdhury, M.A. Kabir, Chen, Jia-Nan, Leng, Xiang-Jun
• Format: Article
• Language: English
• Subjects: Aquaculture; Carassius auratus gibelio; Carp; Diet; Extruded diet; Freshwater; Gibel carp; Growth; Nutrient retention; Pelleted diet; Protease; Proteases; Proteins
• ISSN: 0044-8486; 1873-5622
• DOI: 10.1016/j.aquaculture.2016.03.049

The present study was conducted to evaluate the effects of exogenous protease supplementation in low fish meal pelleted and extruded diets on growth, nutrient retention and digestibility, and serum biochemical indices of gibel carp, Carassius auratus gibelio. A high-fish meal (HF) diet containing 90g/kg fish meal and a low-fish meal (LF) diet containing 30g/kg fish meal (60g/kg fish meal was isonitrogenously replaced by soybean meal) were designed as the positive and negative control diet, and 125, 150 and 175mg/kg exogenous protease were supplemented in the LF diet, respectively. The five formulas were then processed with pelleting and extruding, respectively, to obtain ten diets. After the pelleting and extruding, the retention rate of the protease activity was 77.98% and 37.65%, respectively. The diets were fed to gibel carp with an initial body weight of 35.0±0.2g for 12weeks. In pelleted diets, the supplementation of 150 and 175mg/kg protease in LF diet significantly improved weight gain, nutrient apparent digestibility coefficients (dry matter and crude protein), nutrient retention (crude protein and crude lipid) and decreased feed conversion ratio (FCR) when compared to negative control (P