Effects of dietary carbohydrate types on growth performance, body composition and health status of juvenile Onychostoma macrolepis

In order to explore the optimal carbohydrate addition types in the dietary of juvenile Onychostoma macrolepis, five diets were prepared with glucose, maltose, dextrin, corn starch and cellulose as carbohydrate sources and the fish was cultured for 56 days. The results showed that, ① The terminal weight, specific growth rate, feed coefficient rate and protein efficiency rate were the best in the maltose group (P<0.05), while those in the cellulose group were the worst (P<0.05). ② The crude fat of whole fish in the cellulose group was the lowest (P<0.05), the crude ash content was significantly higher than that in the maltose group (P<0.05), the muscle glycogen content in the maltose and cellulose groups was the lowest (P<0.05), and liver glycogen in the dextrin group was the lowest (P<0.05). ③ Principal component analysis showed that the ratios of C16:0, SFA, MUFA and PUFA had a major effect on the overall fatty acid ratio of the liver. Among them, the ratios of C16:0 and SFA were significantly increased in the maltose group (P<0.05), while the ratio of MUFA in the dextrin group (P<0.05), and the ratio of PUFA in the cellulose group were also significantly increased (P<0.05). The proportions of C18:1n-9 and MUFA had the main effect on the overall fatty acid composition of muscle and adipose tissues, and the proportions of the two were significantly increased in the maltose group (P<0.05). ④ Glutamic pyruvic transaminase in serum of maltose and cellulose groups is the highest (P<0.05), while that of aspartate aminotransferase was the highest in maltose group (P<0.05). Alkaline phosphatase activity and globulin content of glucose and cellulose group were the highest, while that of blood glucose was the reverse (P<0.05). ⑤ The contents of catalase, total superoxide dismutase, glutathione peroxidase in the liver of the maltose group were the highest (P<0.05), while the malondialdehyde content in the cellulose group was the highest (P<0.05). In conclusion, maltose was the most suitable carbohydrate source for juvenile O. macrolepis, followed by dextrin and corn starch, and cellulose and glucose were not the suitable carbohydrate source for the fish; corn starch is recommended as a carbohydrate source in practical production, which will provide an important reference for research and development of its specific compound feed.