No abstract

No abstract

Wheat gluten meal (WGM) was evaluated as a replacement of fish meal (FM) for juvenile Larimichthys crocea．FM was replaced by 0%, 25%, 50%, 75%, and 100% of WGM (WGM0, WGM25, WGM50, WGM75, and WGM100, respectively). In addition, all diets except the control group were supplemented with amino acids. Fish were fed twice daily for 56 days. There were no significant differences in survival and feed conversion ratio (FCR) among all treatments (P>0.05). WGM25, WGM50, and WGM75 groups had significantly higher specific growth rate (SGR) and weight gain ratio (WGR) than those fed with WGM0 (P<0.05). There were no significant differences in mucosal thickness (MT), lamina propria width (LW), mucosal fold height (MH), and goblet cell quantity of single hair (GC) for all the diets (P>0.05). The indexes of Chao1, Shannon, Simpson, and Good coverage in fish fed with WGM0, WGM50, and WGM100 were not significantly affected (P>0.05). Firmicutes (81.03~94.03%) were the dominant bacterial community in juvenile large yellow croaker. Compared with the WGM0 group, the abundance of Firmicutes increased significantly, and Proteobacteria decreased significantly in the WGM100 group (P<0.05). These results suggested that WGM could replace 366.3 g kg-1 FM of the juvenile large yellow croaker diet.

A trend in large yellow croaker (Larimichthys crocea) aquaculture is to establish production sites suitable for extreme weather conditions. However, continuous and strong currents can harm fish welfare. To determine a suitable site location, the swimming ability of large yellow croakers must be assessed. This study aims to provide novel insights into the physiological characteristics of large yellow croaker swimming and a reference for fishing and cage site selection. Currently, research on large yellow croakers has focused on behavior analysis. Herein, we investigate the effects of swimming on large yellow croakers’ metabolites by examining the preferred speed of the group and the sustained swimming ability of single-tailed fish. We evaluated factors that influence the large yellow croaker’s swimming fatigue by quantifying the metabolite contents and constructing a sustained swimming model. The results showed that large yellow croaker populations tend to grow in low-velocity environments, similar to their traditional habitat. The samples were taken at different swimming times at a flow velocity of 0.35 m/s. According to the results of the metabolite content analysis, blood glucose levels are closely associated with the swimming ability in large yellow croakers. The content of liver glycogen, which regulates blood glucose concentration, decreased in a certain linear relationship. The sustained swimming model of the large yellow croaker was constructed according to the changes in liver glycogen content. Based on our findings, we recommend the following: (1) for large yellow croakers with a size of approximately 13.5 cm (approximately 1 year old), the water velocity inside the cage should not exceed 2.6 BL/s; (2) the concentration of liver glycogen limits the sustained swimming ability of the large yellow croaker, providing a reference for studying the swimming ability of other fish.

This study investigated the effects of Setipinna taty protein peptides on the growth, body composition, antioxidant ability and intestinal flora of juvenile Nibea albiflora. The results of this study indicated that there were no significant differences between the control and experimental groups regarding survival, specific growth rate (SGR), feed conversion rate (FCR) and body composition (p > 0.05). Also, there were no significant differences among the control and experimental groups regarding the superoxide dismutase (SOD), glutathione peroxidase (GSH‐PX) and malondialdehyde (MDA) contents of juvenile Nibea albiflora (p > 0.05). For catalase (CAT), the contents of the 42 mg/ml and 21 mg/ml groups were significantly higher than that of the control group (p < 0.05). Regarding lysozyme (LYZ), the content of the 42 mg/ml group was significantly higher than those of the control and 21 mg/ml groups (p < 0.05). The alpha diversity did not exhibit significant differences between the control and experimental groups (p > 0.05). At the phylum level, the dominant intestinal flora in the experimental groups were Tenericutes and Proteobacteria, which accounted for approximately 90.94% of the total flora. At the genus level, Mycoplasma was more abundant in the control group, and Marivita and Qidonghai fungi were the dominant genera in the experimental groups. The results of this study demonstrated that the Setipinna taty protein peptides can change the abundance of the dominant community in the intestine of juvenile Nibea albiflora.