Aquaculture Nutrition最新文献

Ornamental fish sector is one of the fastest growing industries in the world with an estimated market value of 18–20 billion USD. Despite its global economic significance, it suffers from several issues notably, high-cost carotenoids, inadequate seed production and antimicrobial resistance (AMR). The existence of multifaceted problems needs an integrated multifunctional solution. The phytobiotics of Murraya koenigii (PMK), also called as curry leaf is known for its diverse bioactive compounds with rich flavonoids and carotenoids, and can be a silver bullet in dealing with the multidimensional issues in ornamental fish sector. The multifunctionality of the selected phytobiotics was assessed in drapefin barb, Oreichthys crenuchoides which is known for its non-chromatic nature with prominent reticulate melanin patterns. The PMK was administered orally at 0, 5, 10, 15 and 20 g/kg diet for 60 days. At the end of the trial, a significant difference was noted in the growth performance and feed utilisation efficiency in PMK-administered groups. The protease and lipase activities were increased significantly by the action of PMK, with the highest enzyme activity recorded at 5 g/kg group and the amylase activity was dropped in all PMK groups, facilitating an improved nutrient assimilation. The PMK regulated liver health, which was evident by the declined levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST) and alkaline phosphatase (ALP) activities in the liver and muscle. Further, haematological profile reflected the enhancement of aerobic metabolism and immunity by PMK. PMK also exhibited antimicrobial activity against selected pathogens. Despite the carotenoid content and mild greenish-yellow tinge on the skin, no significant skin colour changes were observed in chromaticity analysis. Instead, the reticulate patterns in O. crenuchoides became prominent due to the rich flavonoid content in PMK. Finally, the performance index and integrated biomarker response (IBR) index pointed out that 10 g/kg PMK as an effective dose of administration to O. crenuchoides considering its efficacy.

Alternative sources of dietary fish oil (FO) are necessary for the growth of the aquaculture industry. This study investigated the potential benefits of black soldier fly larvae oil (BSFLO) as a feed ingredient in the diets of African catfish hybrids (Clarias gariepinus × Heterobranchus longifilis). Three isonitrogenous and isolipidic diets—a control diet (CTR) containing a FO and rapeseed oil (RO) mixture (50:50), IO50 containing BSFLO replacing 50% of FO and RO mixture and IO100 containing 100% BSFLO—were formulated. A total of 900 fish juveniles (average initial weight: 29.1 ± 1.69 g) were randomly distributed into three dietary groups, each replicated three times and reared in a recirculation aquaculture system for 7 weeks. Results showed similar fish growth between dietary groups (final body weight: CTR, 155.27 ± 4.45 g; IO50, 162.47 ± 0.19 g; IO100, 160.87 ± 3.78 g). In addition, nutrient utilisation parameters and whole-body crude protein, lipid and ash content were similar between groups. The levels of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in the whole body decreased while that of arachidonic acid (ARA) increased with IO inclusion. Similar trends in ARA and EPA levels were observed in the liver, the DHA/EPA ratio being highest in fish fed IO100 diet. The hepatic expression of pparα (peroxisome proliferators activated receptor alpha), hnf4α (hepatocyte nuclear factor 4α) and hadh (hydroxyacyl-CoA dehydrogenase) followed quadratic trends being lowest in fish fed IO50 and highest in fish fed IO100. The lpl (lipoprotein lipase, LIPA) gene was significantly upregulated in fish fed IO100. The liver malondialdehyde (MDA) content was lowest in fish fed IO50. In addition, plasma myeloperoxidase (MPO) activity linearly increased with IO inclusion. These results demonstrate that potential benefits are achieved when BSFLO is supplemented in diets of African catfish hybrids, contributing to the development of sustainable alternatives to fish and vegetable oils (VOs) in aquafeeds.

In aquaculture, the use of probiotics to improve growth, immunity, and stress resistance in crustaceans has gained increasing attention. This study examined the effects of incorporating different levels of Rhodotorula mucilaginosa (0.0, 0.1, 1.0, and 10.0 g/kg) into the diet on growth performance, antioxidant capacity (AOC), immune function, Toll/Imd, and JAK-STAT signaling pathways in red claw crayfish (Cherax quadricanatus). The investigation was conducted through a 56-day feeding trial. The main results are as follows: Compared with the control group (0.0 g/kg), different R. mucilaginosa levels significantly increased (p < 0.05) the specific growth rate (SGR) and weight gain rate (WGR) of red claw crayfish, significantly increased (p < 0.05) the activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX), glutathione S-transferase (GST), total AOC (T-AOC), and acid phosphatase (ACP) in hepatopancreas of red claw crayfish, and significantly upregulated (p < 0.05) the relative expression levels of tumor necrosis factor receptor-associated protein 6, akirin, immunodeficiency homolog, interferon regulatory factor 4, Toll-like receptor (TLR) 6, TLR 2, Janus kinase, signal transducer activator of transcription, tumor necrosis factor α, interleukin-1β, transforming growth factor-β1 genes in the hepatopancreas of red claw crayfish. In conclusion, R. mucilaginosa significantly enhanced red claw crayfish’s growth, AOC, and immune function, and activated the Toll/Imd and JAK-STAT signaling pathways. In this experimental context, the ideal addition level of R. mucilaginosa is 1.0 g/kg.

The present study aims to develop a more valuable innovative aquaculture feed for the sustainable Lates calcarifer aquaculture industry. An experiment with a completely random design was developed with five groups containing 0% immunostimulant and 0.5% ginger, 1.0% garlic, 0.15% palm carotene alone or in combination. Each diet was randomly assigned to triplicate groups of 30 fish (10.06 ± 0.09 g) per tank. The fish were fed once daily to apparent satiation. Throughout the 56-day feeding trial, the results suggest that although no significant differences were observed among almost all experimental groups in growth performance, feed efficiency, fish composition and disease resistance, the palm carotene supplementations downregulated intestinal tumor necrosis factor alpha (TNF-α) and interleukin (IL)-6 expression, decreased sum scores of liver pathological changes, increased intestinal villus surface (VS) compared with the control group. Moreover, the combined treatment shows more promising immune gene expression (intestinal IL-1 beta (IL-1β) was also downregulated compared to the control), liver and intestinal protection (lower sum scores of liver pathological changes and larger intestinal VS than palm carotene alone supplementation, goblet cell (GC) number per intestinal villus was also increased compared to the control) effects on L. calcarifer infected with Vibrio parahaemolyticus. Therefore, a combination of 0.5% ginger, 1.0% garlic, and 0.15% palm carotene in the diet of L. calcarifer can be used as an immune booster due to fishmeal substitution to obtain better immunocompetence.

Glucoside is the main antinutritional factor (ANF) of rapeseed meal. In the present study, a bacterium with high efficiency in degrading rapeseed glucoside was screened from pond water. The initial concentration of 1.0 × 10⁷ CFU/mL bacterial solution was added to rapeseed meal and fermented for 48 h with a degradation rate of glucoside and isothiocyanate of 67% and 54%, respectively. BSY82 was identified by PacBio third-generation sequencing, and its biology was analyzed. Results showed that BSY82 belongs to Bacillus subtilis. The total length of genome was 4,242,094 bp, among which 89% was coding genes (3,777,298 bp). No virulence factors were predicted, based on a comparative analysis of the strain’s coding genes against known virulence factor databases. Functional analysis showed that BSY82 had the ability to produce myrosinase. The activity of myrosinase in the crude enzyme solution of the strain was 1.67 and 2.12 μmol/min by spectrophotometry and high-performance liquid chromatography (HPLC). The results indicated that BSY82 strain could be used as the optimal material in rapeseed meal fermentation detoxification process.