Aquaculture Nutrition最新文献

This study was to investigate the in vitro antimicrobial activity of fish protein hydrolysate (FPH) against Vibrio harveyi, V. anguillarum, and V. scophthalmi, as well as the nonspecific immunity, intestinal microbiota, and disease resistance to V. harveyi in turbot. FPH was prepared from Pollock. The antibacterial activity of FPH was measured by the agar well diffusion, turbidometric assay, and plate count. The feeding trial was performed to study the effect of FPH on the resistance against V. harveyi in turbot after feeding three diets containing a high level of fish meal (FM), a high level of soybean meal (SM), and 100 g/kg FPH. Agar well diffusion showed the clearest inhibition zone of FPH was observed against V. harveyi, followed by V. scophthalmi. The bacterial growth curve and plate count showed a slight antibacterial effect of FPH against V. anguillarum. Results of the feeding trial showed that FPH enhanced antioxidant and immune responses before V. harveyi challenge as modulating immunoglobulin M (IgM), catalase (CAT), and myeloperoxidase (MPO) activities in serum, as well as the number of goblet cells in the intestine. Meanwhile, the expression of some pro-inflammatory cytokines (interleukin-1β [il-1β], il-6, and il-8) was downregulated in the FPH group after the V. harveyi challenge. Survival probability in the FPH group increased after challenging to V. harveyi based on the Kaplan–Meier analysis. Results of intestinal microbiota showed the relative abundance of Vibrio in the SM group was the highest, followed by the FPH and control groups. Similarly, the relative abundance of distal intestinal V. harveyi was significantly reduced in the FPH group by analyzing the vhhp2 gene. In conclusion, the present FPH against Vibrio strains was species-specific, with stronger antibacterial activity to V. harveyi. Dietary FPH enhanced the nonspecific immunity and antibacterial activity of turbot, increasing the resistance to V. harveyi.

Long-chain polyunsaturated fatty acids (LC-PUFA) play key roles in sex steroid hormone synthesis in fish. Regarding docosahexaenoic acid (DHA), currently the regulating effects were mostly evaluated in female fish rather than males. This study aimed to investigate the DHA effects on the sex steroid hormone production in male Chinese tongue sole. Three experimental diets were prepared, containing different DHA levels: a control (C) group (5.16% DHA of total fatty acids [TFA]), a low DHA group (DHA-L, 8.93%), and a high DHA group (DHA-H, 16.47%). A 58-day feeding experiment was conducted, and each diet was fed to triplicate tanks of fish. Additionally, an in vitro study with Leydig’s cells of this species was conducted to validate the in vivo results. The concentration of testosterone (T) and 11-ketotestosterone (11-KT) in the serum increased with increasing levels of dietary DHA. Dietary DHA significantly upregulated the expression of steroid hormone biosynthetic genes p450c17, hsd17b1, hsd3b1, aromatase, hsd11b2, and p45011b in the testis. The protein expression of Hsd17b1 in the testis of the DHA-H group was significantly higher compared to the other two groups, while the expression level of P450c17 showed an increasing trend with increasing dietary DHA levels. However, the in vitro results confirmed that the final concentration of DHA at 50 μmol/L could significantly increase the gene expression of p450c17 in Leydig’s cells. In conclusion, dietary DHA may promote the synthesis of T and 11-KT through the regulation of protein (Hsd17b1 and P450c17) and gene (p450c17, hsd17b1, hsd3b1, aromatase, hsd11b2, and p45011b) expression of a series of key steroid hormone biosynthetic enzymes in male Chinese tongue sole.

Wild stocks of lake whitefish (Coregonus clupeaformis) are declining in the Great Lakes, and there is a lack of information on their nutritional requirements and gut health indicators to effectively culture them in an aquaculture setting. The aim of this study was to evaluate the growth performance, nutrient utilization, and gut microbiome of lake whitefish fed varying protein:lipid ratios with and without the inclusion of insect meal from black soldier fly (BSF). In total, 450 lake whitefish (301 ± 10 g) were fed one of five diets with differing protein-to-lipid ratios (high-protein 54%, low-protein 48%, high-lipid 18%, or low-lipid 12%), and an additional commercial control rainbow trout diet (Bluewater commercial control [BCC]). High-protein diets included 5% BSF meal to explore its potential to partially replace fishmeal in the diet. After 16 weeks at 8.5°C, growth performance and nutrient digestibility were the highest for lake whitefish fed the high-protein–high-lipid (HPHL) and BCC diets, while the feed conversion ratio (FCR) was numerically lowest for the HPHL. Protein and energy retention, and lipid digestibility were highest for fish fed the HPHL and BCC diets, while the BCC diet had the highest lipid retained, concomitant with high viscerosomatic index (VSI). High lipid in fish, especially in the viscera that is removed during processing, is not desirable, thus the HPHL diet is recommended. The gut microbiome was dominated by Proteobacteria, specifically by the genera of Shewanella and Aeromonas, although feeding high-lipid diets resulted in the lowest alpha diversity, but was not significant. These results are novel for this species, and we recommend that lake whitefish diets should be formulated to have a minimum 54:18 protein-to-lipid ratio. The results from this study provide baseline information on the nutrition and gut microbiome of lake whitefish, which can be used to develop a species-specific feed rather than feeding them rainbow trout feed. However, further work on targeted breeding and genetic selection of broodstock, together with diet optimization, is needed to improve the growth performance and nutrient utilization in order to enable an effective, economical, and environmentally sustainable culture of lake whitefish.

Biofloc technology (BFT) has recently attracted great attention due to minimal water exchange and reduced feed intake. This study aimed to recognize daily changes in the digestive physiology of Oreochromis niloticus between a traditional system and BFT. The enzyme activity of trypsin (try), chymotrypsin (chy), leucine aminopeptidase (lap), alkaline proteases (alk), lipase (lip), and amylase (amy), along with the gene expression of trypsin (try), chymotrypsin (chy), pepsin (pep), amylase (amy), and phospholipase (pla) were measured throughout a daily cycle. Samples were taken every 4 h in a 24 h cycle under a 12:12 L:D photoperiod. During 60 days, fish were feed three times a day (zeitgeber time, ZT: 0, 4, and 8) with a fishmeal-based diet containing 32% of crude protein and 5% of lipid, where molasses was added as a carbon source in BFT. No significant differences were found in fish performance among treatments at the end of the experiment. The activity of all tested enzymes significantly (p < 0.05) increases during the dark period in both treatments, where the same activity pattern was found in try and lip. The maximum expression levels of digestive gene enzymes between treatments show a marked effect dependent on the presence of light and dark phases. The cosinor analysis showed an activity in try, lap, and lip with a significant rhythmicity (p < 0.05). Our results demonstrate that some processes related to the digestive physiology of tilapia that respond directly to daily rhythmicity are modified under the constant presence of feed in BFT. These findings should be considered when establishing new optimized culture protocols.

This study was carried out to search for the protein requirement of a new strain of preponderant amphitriploid Carassius clone, which integrated genomes partly from white crucian carp (C. auratus cuvieri). Seven groups of fish (body weight: 9.73 ± 0.03 g) were fed with seven isolipidic and isocarbohydrate diets containing 21.38%, 25.82%, 27.94%, 31.36%, 34.23%, 37.87%, and 40.70% crude protein (P21, P24, P27, P30, P33, P36, and P39), respectively. After 8-week feeding, weight gain rate (WGR) and specific growth rate (SGR) were lower in the P30 group than those in the P39 group, but no difference was found in final body weight (FBW), survival, condition factor (CF), or hepatosomatic index (HSI) between different groups. Increased dietary protein decreased feeding rate (FR) and viscerosomatic index (VSI) while improved feed efficiency (FE). Decreased protein retention efficiency (PRE) and improved activity of liver alanine aminotransferase (ALT) and content of plasma ammonia suggested intensified fish amino acid catabolism in high dietary protein groups. The dietary protein requirement of the new Carassius clone was as low as 21.38% for growth. The optimal dietary protein for high FE was 39.62% and should be less than 30.56% to maintain the maximum protein retention. High dietary protein might be harmful to the fish due to the increased contents of liver malondialdehyde (MDA) and plasma cortisol. Dietary protein level altered fish body and muscle flavor substance composition. Low dietary protein could obtain high muscle fatty acid, free amino acid, and lipid accumulation, including whole body and muscle crude lipid, plasma total triglyceride (TG), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-c), and low-density lipoprotein cholesterol (LDL-c). Therefore, the recommended dietary protein for this new Carassius clone juvenile should be 21.38%–30.56%.

This study aimed to assess the impact of incorporating rapeseed meal (RM) as a partial substitute for fish meal (FM) in the diet of cultured hybrid sturgeon (Acipenser schrenckii ♀ × Acipenser baerii ♂). A total of 450 juvenile hybrid sturgeon with similar weights were randomly assigned to five dietary groups, each with triplicates of 30 fish per tank. For 12 weeks, FM was replaced with varying percentages of RM (0%, 25%, 50%, 75%, and 100%). Results indicated a decreasing trend in final body weight (FBW), weight gain, and survival rates (SRs) as the ratio of RM increased. Growth performance was less affected when the substitution ratio of FM was below 50%. The replacement of FM with RM showed a decreasing trend in crude protein and ash content of sturgeon body composition and no significant effect on moisture and crude lipid content (p > 0.05). Essential amino acids (EAAs) in whole fish, such as methionine (Met), threonine (Thr), and lysine (Lys), increased with higher substitution rates (p > 0.05). The lysozyme (LZM) activities in the pyloric cecum, duodenum, and valve intestine of the sturgeon showed a decreasing trend (p > 0.05). Nevertheless, at a 50% substitution level, sturgeon liver superoxide dismutase (SOD) and malondialdehyde (MDA) activities reached their peak. At 100% substitution, serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities were significantly higher than in other groups (p < 0.05). At 50% substitution, sturgeon valve intestinal protease activity reached its maximum, and the duodenal villus height (VH) was not significantly different from that of the control group (morphological and structural indices were lower in the treatment groups). Gene expression of pro-inflammatory factors IL-1β, IL-6, IL-8, and TNF-α increased with the substitution ratio, while anti-inflammatory factor IL-10 showed the opposite trend. NF-κB and myeloid differentiation factor 88 (MyD88) expression increased with substitution ratio, and Toll-like receptor 1 (TLR1) and Toll-like receptor 2 (TLR2) showed the opposite trend in the intestine. The results of this study suggest that replacing less than 50% of fishmeal with RM in hybrid sturgeon diets can reduce the amount of fishmeal used without compromising fish health.

Ricefield eel is an important economic fish in China. However, large-scale intensive breeding has increased the incidence of diseases in eels. In this study, we conducted an 8-week feeding trial to investigate the effects of β-glucan on the growth performance, intestinal health, and Aeromonas veronii resistance of Monopterus albus (M. albus). Three hundred healthy fish (initial body weight: 12.38 ± 0.50 g) were randomly divided into five groups: A1 (basal diet) was considered the control group, whereas A2, A3, A4, and A5 were the experimental groups. The fish in the experimental groups were fed a basal diet supplemented with 250, 500, 1000, and 2000 mg/kg β-glucan, respectively. The addition of 0.025%–0.2% β-glucan resulted in a notable enhancement of eel growth performance, with the most significant improvement observed in eels supplemented with 0.1% β-glucan (p < 0.05). Furthermore, 0.025%–0.2% β-glucan could significantly enhance the antioxidant properties of the eel intestinal tract (p < 0.05), and the addition of 0.1% β-glucan significantly improved trypsin (TPS), amylase (AMS), and lipase (LPS) activities in the intestine (p < 0.05). In terms of intestinal histology, the A3, A4, and A5 groups exhibited significantly greater villus height compared to the control group (p < 0.05). Concentrations of β-glucan at 0.1% and 0.2% enhanced the composition of the intestinal flora; specifically, the relative abundance of Proteobacteria increased, while the relative abundance of Firmicutes decreased. Moreover, the addition of 0.05%–0.2% β-glucan significantly improved the relative survival rate (SR) of A. veronii-infected eels and significantly decreased the bacterial load of the liver, spleen, and kidney (p < 0.05). In comparison to eels that did not receive β-glucan supplementation, eels supplemented with 0.2% β-glucan exhibited decreased intestinal structural damage. In summary, the addition of 0.1%–0.2% β-glucan can promote eel growth, improve intestinal digestion and antioxidant capacity, regulate intestinal flora, and enhance intestinal physical function and anti-infection ability.

Aquaculture plays a critical role in global food security, with Nile tilapia (Oreochromis niloticus) recognized for its adaptability and robust growth. However, traditional feeds, heavily reliant on fishmeal (FM) and soybean meal, face economic and environmental challenges. In response, black soldier fly larvae meal (BSFLM) has emerged as a promising, nutrient-dense alternative. This review synthesizes existing literature on BSFLM’s nutritional profile and its suitability for Nile tilapia diets, while acknowledging that the data come from diverse independent studies conducted under varying environmental conditions and husbandry practices. BSFLM consistently provides high-quality protein (29.9%–48.2%), aligning with tilapia’s requirements, and is rich in essential minerals and fatty acids. While its lipid content (25.69%–28.43%) may require processing adjustments, the overall profile supports tilapia health and growth. Trends from case studies suggest that certain systems, such as hapas placed in ponds, have reported favorable growth and feed conversion efficiencies at 50% FM replacement levels. However, these findings cannot be directly compared across all studies due to differences in methodologies, culture conditions, and inclusion rates. Instead, they collectively indicate that BSFLM can effectively replace traditional protein sources and enhance sustainability. As research and production scale up, careful consideration of context, system design, and feed formulations will be essential. Collaborative efforts among researchers, industry, and policymakers will further refine the use of BSFLM, ultimately advancing the environmental and economic sustainability of Nile tilapia aquaculture.

Soybean meal (SBM) remains a primary protein source in aquafeeds. This study investigated the potential of winged bean (Psophocarpus tetragonolobus) meal as a SBM replacement in diets for butter catfish (Ompok bimaculatus) juveniles (mean weight: 1.24 ± 0.23 g). A response surface methodology (RSM) optimized processing conditions to minimize antinutritional factors (ANFs) in winged bean meal (WBM), resulting in minimized tannin (4.14 ± 0.018 mg/g at 40 min, 110°C), phytate (0.414 ± 0.0009 mg/g at 31.67 min, 104.5°C) and trypsin inhibitor activity (70.8 ± 0.06% inhibition at 20 min, 90°C). Experimental diets containing 30% crude protein and varying levels of WBM substitution (0%, 25%, 50%, 75% and 100%) were fed for 70 days. Growth performance, measured by weight gain, was significantly higher in the 25% substitution group (p < 0.05) but not significantly different from the control at 50% substitution. Quadratic regression analysis predicted an optimal inclusion level of 15.10% for maximizing weight gain. Survival rates did not differ significantly among treatments (p > 0.05). Feed utilization was most efficient in the 25% substitution group. Haematological and immunological parameters indicated improved fish health at the 25% substitution level. Flesh quality attributes, including texture profile analysis, pH and antioxidant activity, were superior in the 25% group compared to other treatments. However, colour enhancement was more pronounced at higher inclusion levels (≥50%). While flesh pH and antioxidant activity suggested potential stress at higher winged bean inclusion levels, the 25% group showed improved values compared to the control. These findings suggest that WBM can potentially replace up to 50% of SBM in butter catfish diets, offering a promising alternative protein source. This study provides preliminary data on the feasibility and prospects of utilizing WBM in O. bimaculatus diets.

Butyrate-producing bacteria (BPB) benefit the health of aquatic animals. This current study aimed to isolate BPB from the intestines of Nibea coibor and assess their probiotic potential. The results showed that nine isolates were obtained in vitro from the gut of N. coibor, including six Clostridium butyricum, two Proteocatella sphenisci, and one Fusobacterium varium. The representative bacteria, C. butyricum CG-3 and P. sphenisci DG-1, which produce high butyrate levels, were further studied for short-chain fatty acid (SCFA) production and antibiotic susceptibility. The effects of BPB singly (CB: basal diet + CG-3 and PS: basal diet + DG-1, at 10⁷ CFU/g) or in combination with galactooligosaccharides (GOS) (0.5%) and inulin (0.5%) (CBIG) or D-sorbitol (0.5%) (PSGS) on the growth and health status of N. coibor were investigated. Results showed an increase in growth parameters in the CB, CBIG, and PSGS groups, except for the PS group. Alterations in intestinal microbiota (including diversity, abundance, and function) were observed in four experimental groups (CB, CBIG, PS, and PSGS groups). SCFA contents increased in treated groups; butyrate production was positively related to bacterial abundance. Compared to control, levels of complement C3, complement C4, immunoglobulin M (IgM), transforming growth factor-β (TGF-β), interleukin (IL)-10, IL-1β, and lysozyme (LZM) increased, while malondialdehyde (MDA) decreased in treated groups. Contents of IL-6 (PS and PSGS groups), tumor necrosis factor-alpha (TNF-α) (CB, PS, and PSGS groups), total antioxidant capacity (T-AOC) (CB and PS groups), total superoxide dismutase (T-SOD) (PS group), catalase (CAT) (CB and PSGS groups), and activities of amylase (PS and PSGS groups), trypsin (CB group), and lipase (CBIG group) were increased. Our results suggested the potential use of C. butyricum CG-1 or P. sphenisci DG-1 singly or in combination with prebiotics improved growth and health conditions in N. coibor.