The efficiency of adding amino acid mixtures to a diet free of fishmeal and soybean meal as an attractant in yellow river carp (Cyprinus carpio var.)

Abstract

Five treatment groups were set up in the feeding experiment: the fishmeal diet (positive control, PC), fishmeal-free diet (negative control, NC), complex amino acid 1 (0.4% alanine, 0.5% arginine and 0.7% glycine, AA1), complex AA2 (0.4% alanine, 0.7% glycine and 0.2% histidine), and complex AA3 (0.5% arginine, 0.7% glycine and 0.2% histidine). Each treatment had 4 replicates with 40 fish (initial weight 12.81 ± 0.17 g). The results showed that compared with the NC group, the complex AA1 and AA2 attractants significantly increased the final body weight, weight gain rate, and specific growth rate and decreased the viscera index and hepatopancreatic index of yellow river carp, and the complex AA1 attractants performed better (P < 0.05). The specific growth rate of the complex AA1 attractants was significantly higher than that of NC group by 4.83%. The results of fish body composition showed that compared with the NC group, the complex AA1 attractants significantly increased the crude protein content of yellow river carp (P < 0.05). Blood biochemical indices showed that the contents of glucose and total protein in the AA1, AA2 and AA3 groups were higher than those in the NC group and lower than those in the PC group (P < 0.05). Compared with the NC group, the activities of serum lysozyme in the AA1, AA2 and AA3 groups increased by 10.36%, 13.21% and 8.86% respectively (P < 0.05). The complex AA1, AA2 and AA3 attractants increased the activities of the superoxide dismutase, catalase, glutathione peroxidase and total antioxidant capacity in the serum, liver, and gill tissue of the yellow river carp, and reduced the malondialdehyde content to a certain extent, among which the complex AA1 attractant was the best. Compared with the NC group, the addition of compound amino acid attractants in the fishmeal-free diet increased the height of the anterior intestinal fold of yellow river carp, and AA1 performed best. The thickness of the anterior intestinal muscle layer in the AA1, AA2 and AA3 groups was higher than that in the NC group to varying degrees (P < 0.05). In summary, the addition of complex amino acid attractants to a fishmeal-free diet can significantly improve the total antioxidant and immune capacity; additionally, the growth performance of yellow river carp was improved. At the same time, the addition of the complex attractant significantly increased the height of the anterior intestinal fold, indicating that the complex amino acid attractants can also promote intestinal digestion and absorption while also reducing intestinal injury. It can be concluded that the complex amino acid attractant combined with 0.4% alanine, 0.5% arginine and 0.7% glycine is more suitable when added to the fishmeal-free diet of the yellow river carp.