In order to explore the effects of probiotics on the water quality, growth performance, nonspecific immunity, digestion, and intestinal flora of Macrobrachium rosenbergii in the biofloc culture system, three groups (six replicates in each group) were set up and divided into no bacteria (control group, Con), Bacillus subtilis (BS), and effective microorganisms (EM) in the current experiment. After dissolution of the water, the carbon source (glucose) was evenly sprayed in the aquaculture tank to construct a biofloc with a C/N of 15. A total of 1260 giant freshwater prawn (Macrobrachium rosenbergii) with an initial body weight of (2.09 ± 0.03) g were randomly assigned to 18 tanks (70 per tank). BS group and EM group significantly reduced total nitrogen concentration. Both BS and EM groups significantly increased final mean body weight, weight gain, and specific growth rate, but significantly decreased feed conversion rate of Macrobrachium rosenbergii. BS group significantly increased plasma superoxide dismutase, lysozyme, and acid phosphatase contents, but significantly decreased plasma malonaldehyde content. EM group significantly increased serum acid phosphatase content and intestinal trypsin activity but significantly decreased the Chao and ACE index of species richness. BS group and EM group significantly decreased the abundance of Chloroflexi and Verrucomicrobiota. BS group significantly increased the abundance of Bacillus. Overall, adding probiotics affected water quality, Macrobrachium rosenbergii performance, and microbial community. The results showed that Bacillus subtilis is a good biofloc probiotic additive.

To investigate the effect of poultry by-product meal (PBM) replacing fish meal on the growth and intestinal health of Chinese soft-shelled turtle (Pelodiscus sinensis). Four experimental diets were prepared. Fish meal was replaced by 0 (control group, PBM0), 5% (PBM5), 10% (PBM10), and 15% (PBM15) PBM. Compared to the control group, final body weight, weight gain, and specific growth rate were significantly increased, while feed conversion rate decreased significantly in the PBM10 group (p < 0.05). The PBM15 group significantly increased the moisture content and significantly decreased the ash content of the turtles (p < 0.05). The PBM5 and PBM15 groups significantly decreased the whole-body crude lipid (p < 0.05). The serum glucose content increased significantly in the PBM10 group (p < 0.05). The liver malonaldehyde content significantly decreased in the PBM5 group and in the PBM10 group (p < 0.05). Liver glutamic-oxalacetic transaminase and intestinal pepsin activity were increased significantly in the PBM15 group (p < 0.05). The expression of the intestinal interleukin 10 (IL-10) gene was significantly down-regulated in the PBM10 group and the PBM15 group (p < 0.05), the expression of the intestinal interferon-γ (IFN-γ), interleukin-8 (IL-8), and liver toll-like receptor 4 (TLR4) and toll-like receptor 5 (TLR5) genes were significantly up-regulated in the PBM5 group (p < 0.05). In summary, poultry by-product meal can be used as a protein source to replace fish meal in turtle feed. Based on quadratic regression analysis, the optimal replacement ratio is 7.39%.

Black soldier fly (Hermetia illucens) larvae meal (BSF meal) has emerged as a promising sustainable protein source in aquafeed formulation. This study examined the effects of graded BSF meal inclusion (0%, 20%, 40%, 60%, 80%, and 100% fishmeal replacement) and die head temperature (80 °C, 100 °C, and 120 °C) on the physical properties of extruded diets for Asian seabass (Lates calcarifer), with particular attention to their interactive effects. Both factors significantly affected most pellet quality parameters (p < 0.05), with the exception that no significant interaction effect was observed for moisture content (p = 0.2817). PDI increased progressively with BSF meal inclusion, peaking at 99.14% at 100% substitution and significantly exceeding the control. Higher BSF meal inclusion levels were associated with reduced expansion ratio (ER), bulk density (BD), and sinking velocity (SV). Notably, pellets produced at 80–100% BSF meal inclusion combined with moderate die temperatures (80–100 °C) achieved complete buoyancy (SV = 0.00 m/s). Processing at 80 °C yielded the highest ER and water absorption index (WAI), while 120 °C was associated with elevated water solubility index (WSI), indicating a higher risk of nutrient leaching. These results suggest that BSF meal can replace fishmeal at up to 100% without compromising pellet durability. Extrusion of BSF-based diets at 60–100% inclusion and 80–100 °C is recommended to achieve an optimal balance of structural integrity, hydration properties, and buoyancy for Asian seabass feeds.

This study evaluated the effects of dietary lipid sources and lysolecithin (LL) supplementation on the growth performance, lipid metabolism, hepatopancreatic histology, and intestinal microbiota of Macrobrachium rosenbergii . A 56‐day feeding trial was conducted using six isonitrogenous diets containing fish oil (FO), soybean oil (SO), or a 1:1 FO–SO blend (mixed oil [MO]), and each supplemented with or without 0.5% LL. Results indicated a significant interaction between dietary lipid sources and LL supplementation on growth performance ( p < 0.05). The MO diet supplemented with LL yielded the highest growth rates, while LL supplementation significantly improved feed efficiency ( p < 0.05). Regarding histological status, the dietary SO treatment induced a significant increase in hepatopancreatic lipid deposition ( p < 0.0001) and histological alterations, while LL supplementation reduced lipid deposition and improved hepatopancreatic morphology. Dietary lipid source significantly affected muscle n‐3 polyunsaturated fatty acids (PUFAs; p < 0.01). However, a significant interaction between dietary lipid source and LL supplementation was observed specifically for hepatopancreatic total n‐3 PUFA ( p = 0.0053). Gene expression analysis confirmed that LL modulates lipid metabolism in a source‐dependent manner, upregulating fatty acid oxidation pathways ( Pparα and Cpt1 ) in FO groups while influencing synthesis pathways ( FAS ) in SO groups ( p < 0.05). Furthermore, LL supplementation significantly altered the composition of intestinal microbiota, specifically enriching beneficial bacterial genera in dietary SO‐treatment ( p < 0.05). In conclusion, the dietary treatment combining MOs and LL showed beneficial effects on growth performance, lipid metabolism, and hepatopancreatic health in M. rosenbergii .