Aquaculture Nutrition最新文献

The present global trade of endemic ornamental fishes is heavily relied wild-caught species that concerns long-term sustainability. This study examined the effects of dietary melatonin on the reproductive performance and health of Devario aequipinnatus (giant danio). A basal diet of 35% protein (basal diet as control) was supplemented with four different doses of melatonin (2 mg [M1], 10 mg [M2], 50 mg [M3] and 100 mg [M4] per 100 g of feed) given to experimental groups in triplicate. Fish (average weight: 1.13 ± 0.15 g) was stocked in tanks (n = 10) and fed 5% of body weight twice daily. After 60-day feeding, key reproductive metrics such as the gonadosomatic index (GSI), fecundity, egg diameter and histological changes were analysed along with growth and physiological status. The GSI was observed to be better with the increase in dosage and was higher in M3 (3.05 ± 0.03%) (p  < 0.05). Histological examination revealed the presence of advanced oocyte stages IV and V in M3, while higher (>50 mg) melatonin levels suppressed the GSI. Egg diameter increased with the dosage of melatonin up to 50 mg/100 g (1.18 ± 0.6 mm). Testicular development was most advanced in 50 mg (M3) dose of melatonin with significant higher appearance of stage II spermatids or spermatozoa. In addition, M3 exhibited markedly elevated levels of vitellogenin (VG) (3.38 ± 0.22 nmol/L) in female fish and testosterone (16.4 ± 1.11 nmol/L) in male fish compared to the control. Broken-line regression analysis indicates that the optimal dose for improved growth performance was identified at 63 mg/100 g of diet. Melatonin supplementation significantly increased (p  < 0.05) haematological indices such as haematocrit value, leucocyte count, haemoglobin (Hb) and packed cell volume (PCV) compared to the control, except for the 100 mg group (M4). Although stress markers such as glucose and cortisol were similar to the control, there was a plausible rise in the amount of antioxidant enzyme (p  < 0.05) in the melatonin groups. Overall findings of the study demonstrate the potential of melatonin improving the reproductive and physiological status of endemic ornamental fish for accelerating the captive breeding programme for sustainable trade.

The present study investigates the effects of dietary phosphatidylcholine (PC) deficiency and its addition on growth and physiological and biochemical indicators of juvenile Eriocheir sinensis under different oil sources. There were no significant differences in the growth and feed utilization between the vegetable oils and fish oil (FO) groups under PC-devoid conditions. In contrast, the FO and perilla oil (PO) groups showed better growth-promoting effects and higher feed utilization than the safflower oil (SO) and olive oil (OO) groups under 3% PC-added condition. Both dietary PC and oil sources (FO or PO) could inhibit lipid accumulation of the whole crab, and dietary PC also observably facilitated whole-body protein deposition. In addition, dietary FO and PO increased the burden of the antioxidant system and the risk of lipid peroxidation in juvenile E. sinensis. Meanwhile, diets supplemented with PC effectively alleviated oxidative stress and lipid peroxidation caused by dietary FO and PO. The composition of fatty acids in muscle and hepatopancreas was positively associated with that in diets. Compared with SO and OO, FO and PO significantly reduced the lipid deposition in the hepatopancreas at 3% PC supplementation, possibly because FO and PO formed new physiological-active PC contained n-3 polyunsaturated fatty acids (PUFAs) with dietary PC through activating PC remodeling reaction, and promoting fatty acid utilization, and finally inhibiting the lipid accumulation in the hepatopancreas. This study indicates that FO and PO are better lipid sources (LSs) for E. sinensis, providing alternative oil sources in the crab diet in combination with PC supplementation.

Feed strategies such as compensatory growth and protein restriction have been applied to optimize growth and feed efficiency in aquatic species. The effects of protein restriction (from 1 to 4 weeks of feeding with dietary 35% protein) and 1 week of fasting on growth, body composition, hemolymph parameters, digestive enzymes, serological enzymes, immune and antioxidant system, and relative gene expressions in whiteleg shrimp (Litopenaeus vannamei) (0.30 ± 0.03 g) were investigated. Treatments were experienced in 1 out of 8 weeks of fasting but not in the Control and 35%P groups. Other groups were 7P40 (1-week fasting), 6P40 (1-week feeding dietary 35% protein), 5P40 (2-week feeding with dietary 35% protein), 4P40 (3-week feeding dietary 35% protein), and 3P40 (4-week feeding dietary 35% protein). The results indicated that there was no difference in weight gain among Control (10.22 g), 7P40 (9.37 g), and 6P40 (9.27 g) groups. Feed efficiency in 35%P was significantly lower than in Control. The 5P40, 4P40, 3P40, and 35%P treatments had lower protein and lipid contents in the body, protease, total protein, and cholesterol compared with the Control. Immunity and antioxidant systems were suppressed by the application of fasting and protein restriction simultaneously so that acid phosphatase, lysozyme, superoxide dismutase, glutathione peroxidase, and lysozyme gene in 4P40, 3P40, and 35%P treatments were lower, and also, these groups had higher alanine aminotransferase levels than the Control. In conclusion, this study suggests that applying both protein restriction and fasting impairs the growth and health of whiteleg shrimp, and at least 6 out of 8 weeks, whiteleg shrimp should be fed with a dietary 40% protein.

A 114-day feeding trial was used to investigate the influence of vitamin A (VA) on growth performance, nonspecific immune responses and shell microbiota in juvenile sea urchin (Strongylocentrotus intermedius). Graded levels of VA (0, 4000, 8000, 16,000, 32,000 and 64,000 IU/kg) were added to make six experimental feeds. Each feed was allocated to three parallel tanks of sea urchins (initial weight 0.87 ± 0.05 g and initial test diameter 1.83 ± 0.57 mm). The data revealed that the weight gain rate (WGR) and gonadosomatic index (GSI) rose markedly as VA addition level increased from 0 to 4000 IU/kg and then reached a plateau with further increase of dietary VA levels. As VA addition level increased, nonspecific immune response of S. intermedius first increased and then decreased, with those fed diets with relatively higher addition of VA (32,000 IU/kg) exhibiting significantly greater phagocytic activity (PA) and acid phosphatase (ACP) activities, as well as upregulated expression of several immune-related genes such as tumour necrosis factor α (TNF-α), antimicrobial peptides (AMPs), toll-like receptors (TLRs) and lysozyme (LYZ). The abundance of Firmicutes, Bacteroidota, Bacteroides and Faecalibacterium increased, but that of Proteobacteria and Leucothrix decreased in the shell of S. intermedius as VA addition level increased. The percentage of sea urchins with severe red spotted disease decreased from 64.44% to13.33% as VA addition level increased to 32,000 IU/kg and subsequently increased to 42.22% with further increase of VA addition level. On the contrary, the percentage of sea urchins with mild red spotted disease increased from13.33% to 55.55% as VA addition level increased to 32,000 IU/kg and subsequently decreased to 31.11% with further increase of VA addition level. These results demonstrated that a low addition level of VA (4000 IU/kg) can help S. intermedius achieve ideal growth performance. However, relatively higher addition levels of VA (32,000 IU/kg) enhanced nonspecific immunity and red spotted disease resistance of S. intermedius, which could be accomplished by promoting immune gene expression and optimizing the shell microbiota composition.

Enterococcus faecium inhabits animal gastrointestinal tracts and has been demonstrated to benefit livestock and poultry, but its effects on soft-shelled turtles remain unexplored. The present work investigates the effects of probiotic E. faecium on intestinal microbiota and barrier structure, immune function, and antioxidant capacity of the soft-shelled turtle. Twenty-four juvenile Pelodiscus sinensis were divided into two groups: control (fed a basal diet) and treatment (fed a diet supplemented with E. faecium, 3.3 × 10⁸ CFU/g feed), over a period of 6 weeks. We found that E. faecium did not promote the growth of turtles at the present feeding level, but the treatment resulted in significant alterations in the intestinal microbial community structure, with increased abundance of Enterococcus, Romboutsia, and Clostridium_sensu_stricto_1, and a reduction in Aeromonas (p  < 0.05). E. faecium notably enhanced villus height/crypt depth, villus width, and villus density in the intestine. The treatment group exhibited a 1.50-fold increase in goblet cells count and a 1.18-fold higher in the muscular layer thickness compared to the control group. E. faecium also improved the immune function, with an increase in the ratio of plasma neutrophils and lymphocytes to the total number of leukocytes after feeding probiotics, and upregulation of the levels of toll-like receptor 4 (TLR 4), lysozyme, interleukin 1β (IL-1β), tumor necrosis factor α (TNF-α), and immunoglobulin A (IgA) in the intestine, as well as the level of hepatic immunoglobulin M (IgM). Additionally, E. faecium supplementation boosted antioxidant capabilities, including a significant increase in catalase (CAT) and glutathione peroxidase (GPx) activity and reduced glutathione (GSH) levels in the intestine and GSH levels in the spleen. Our study demonstrates the beneficial effects of supplemental E. faecium on the intestine and overall health of soft-shelled turtles, particularly in enhancing their immune function and antioxidant capacity.

Diseases, overfishing, and habitat loss are constantly reducing oyster populations. Moreover, environmental pollution and natural disasters also hinder offshore shellfish cultivation. Therefore, filter-feeding bivalves could be cultivated on land-based system to maintain the culture condition and secure food safety. Four different diets including Chaetoceros gracilis (CG), Tetraselmis chuii (TC), mixture of CG and TC (CG/TC), and fresh seawater without feed (Con) were trialed for Crassostrea belcheri spat in this research. After 35 days of culture, the highest survival rate (SR), volume, and weight increment (WI) of oyster and improved water quality appeared in CG/TC. In the same manner, CG/TC diet exhibited greater lipase (LPS), pepsin (PES), catalase (CAT), alkaline phosphatase (AKP), and hydrogen peroxide (H₂O₂) activity. Conversely, amylase (AMS), acid phosphatase (ACP), superoxide dimutase (SOD), malondialdehyde (MDA), and lysozymes (LZMs) activities were substantially higher in CG diet compared to TC, CG/TC, and Con. No significant differences were observed among CG, TC, and CG/TC for antioxidant capacity (AOC). In this investigation, mixed algal diet had excellent results for the growth and development of oyster, whereas unialgal diet improved immunity and AOC to survive in unfavorable conditions. This observation help elucidates the knowledge on microalgal diet influenced immune modulation and health of marine bivalves in the scenario of land-based farming.

Two types of bile acids (BAs), named fermented bile acids (FBAs) and 170HDa, were produced by a biological approach to assess their effects on growth performance, metabolism, and intestinal health in white shrimp. In this study, five experimental diets were prepared with varying levels of FBAs (0.02% for A1, 0.03% for A2, 0.04% for A3, 0.05% for A4, and 0.06% for A5) and five diets containing different concentrations of 170HDa (0.02% for B1, 0.03% for B2, 0.04% for B3, 0.05% for B4, and 0.06% for B5). Additionally, positive diets (P) with commercial BAs at a level of 0.04%, along with and negative diet (N) without BA supplementation, were included as controls. FBAs and 170HDa were found to improve the growth performance including final weight, weight gain, and specific growth rate and reduce the activities of aspartate aminotransferase and alanine aminotransferase in hemolymph. The alkaline phosphatase (AKP) activity of hemolymph in shrimp treated with FBAs was generally higher than in groups treated with 170HDa and the control groups. However, the acid phosphatase (ACP) activity of hemolymph in shrimp treated with FBAs showed similar levels to those treated with 170HDa and the control groups. The gene expression levels of antilipopolysaccharride factor (ALF) and proPO were significantly lower in most FBAs and 170HDa-treated groups compared to the control groups (p < 0.05). Additionally, the gene expression levels of α2M in hepatopancreas were significantly higher in the 170HDa-treated groups compared to those in the FBAs-treated group (p < 0.05). The FBAs and 170HDa significantly enhanced the intestinal health by boosting the proinflammatory capacity and increasing the diversity of the intestinal microbiota, thereby combating pathogenic microorganisms. Notably, there was a significant increase (p < 0.05) in the abundance of Proteobacteria, Firmicutes, Tenericutes, and Cyanobacteria at the phylum level, as well as Vibrio, Rhodobacter, and Shewanella at the genus level, respectively. These findings indicate that dietary FBAs and 170HDa have positive effects on growth performance and intestinal health by modulating lipid metabolic profiles, immune responses, the integrity of intestinal wall, and the diversity of intestinal microbes in white shrimp. This study suggests that FBAs and 170HDa could serve as effective dietary supplements to enhance shrimp production and health management in aquaculture, providing a promising strategy for sustainable aquaculture practices.

Whitefish fisheries’ side-stream biomass is an abundant underutilized resource that can be valorized to benefit future aquaculture sustainability. Four novel ingredients based on side-streams from Atlantic cod (Gadus morhua) fileting were produced. FM-hb, a fish meal (FM), and FPH-hb, a fish protein hydrolysate based on heads (h) and backbones (b); FM-hbg, a FM based on heads, backbones, and viscera/guts (g); and FPC-g, a fish protein concentrate based on viscera preserved in formic acid. Four diets were prepared containing one of the ingredients replacing 50% of the dietary FM protein, in addition to a positive (FM10) and a negative (FM5) control. The six diets were fed to triplicate tanks with Atlantic salmon (Salmo salar L.; 113 ± 1 g) over 8 weeks. Besides general performance, gut and brain gene expression for selected hormones and key neuropeptides involved in the control of appetite and digestive processes were studied during feeding and postprandial, and possible reference levels for Atlantic salmon were established. All side-stream-added diets performed well, with no significant differences in performance and biometrics between the treatments. Some gene expression differences were observed, but no well-defined patterns emerged supporting clear dietary effects related to digestive performance or appetite. However, in the brain, a short-time upregulation of agouti-related protein-1 (agrp1), corresponded to higher cumulative feed intake (FI) for the FM10 diet supporting notions that this may be a candidate biomarker for appetite in salmon. Expression of stomach ghrelin-1 (ghrl1) was higher than ghrelin-2 (ghrl2) and membrane-bound O-acyltransferase domain-containing 4 (mboat4), and midgut peptide YYa-2 (pyya2) and glucagon-a (gcga) were higher than peptide YYb-1 (pyyb1). A comparison showed that midgut peptide YYa-1 (pyya1), pyya2, and gcga expressions were higher than in the hindgut, which is opposite of what is found in mammals. In conclusion, this study shows that sustainable side-stream raw materials with different characteristics can partly replace high-quality commercial FMs giving similar performance.

The digestibility of defatted mealworm (DMW, Tenebrio molitor) and its substitution for fishmeal (FM) in rainbow trout (Oncorhynchus mykiss) diets was determined. In the first trial, a diet with 40% FM was considered as the control (Diet 1), and four other diets replaced 25% (Diet 2), 50% (Diet 3), 75% (Diet 4), and 100% (Diet 5) of FM with DMW. In the second trial, the in vivo digestibility of DMW was assessed. Results of the first trial showed no significant differences in fish growth and feed utilization performance among dietary groups (p  > 0.05). Fish fed the highest DMW level showed significantly higher whole-body lipid and energy composition compared to fish fed the control diet. Substitution of FM with DMW did not significantly affect hematological electrolyte, acid–base, and blood gas parameters, except for sodium (Na) concentration. The measured mean score of histopathological features did not show significant degradation of the distal intestine when FM was completely replaced. A significantly lower liver inflammation was observed in fish-fed Diet 3 compared to fish-fed Diet 5. Based on the results of the second experiment, the apparent digestibility coefficient of dry matter, protein, lipid, energy, and phosphorus were 80%, 87%, 100%, 84%, and 90%, respectively, and all essential amino acid digestibility coefficients were >90%. Overall, the highly digestible DMW can fully replace FM in the diet, up to 40% as fed, with little to no impact on the health, growth performance, feed efficiency, and fillet composition. When considering all parameters evaluated, an inclusion level between 20% and 30% (as fed) or 50%–75% of FM replacement was found to yield the best performance and fish health.

This experiment aimed to assess the dietary adaptation and utilization of high carbohydrate diets to Ying carp and scattered-scaled mirror carp (Cyprinus carpio), focusing on growth performance, muscle nutritive value, and nutrient metabolism. Ying carp (4.5 ± 0.2 g) and scattered-scaled mirror carp (5.01 ± 0.2 g) were fed isonitrogenous diets containing 20%, 30%, and 40% carbohydrates for 8 weeks; the nitrogen content of the three feeds was (5.12% ± 0.03%). After the trail, the final body weight, feed efficiency, and specific growth rate of both carp varieties were analyzed. Results showed that the final body weight, feed efficiency, and specific growth rate of both carp varieties were significantly higher at the 30% carbohydrate level compared to 20% and 40%, indicating improved growth performance (p < 0.05). Crude protein content in whole fish composition was significantly higher at the 30% carbohydrate level compared to the other two levels (p < 0.05) for both varieties. However, excessive carbohydrate intake (40%) led to pronounced liver fat deposition in both varieties, with scattered-scaled mirror carp showing less severe deposition than Ying carp. As the carbohydrate levels in the feed increased, the essential amino acid (EAA) and total amino acid (TAA) content in the muscle of both carp varieties significantly increased, while the content of unsaturated fatty acids in the muscle significantly decreased (p < 0.05). Gene expression analysis revealed enhanced glycolytic activity (pk1) and inhibited gluconeogenesis (g6p and pepck) in the liver with higher carbohydrate levels. In muscle tissue, high carbohydrate diets reduced expression levels of genes involved in polyunsaturated fatty acid (PUFA) synthesis (elovl5, elovl6, and rxrgb). The two carp varieties exhibited distinct adaptations to varying dietary carbohydrate levels. While a 30% carbohydrate diet enhanced the growth performance of both varieties, scattered-scaled mirror carp demonstrated higher growth efficiency, whereas Ying carp excelled in maintaining muscle nutrient quality, particularly regarding PUFAs and amino acid composition. These findings suggest that carbohydrate levels in feed should be optimized based on the specific goals of aquaculture, whether prioritizing rapid growth or improved muscle nutrition. Moreover, variations in the expression of genes related to carbohydrate metabolism between the two varieties influenced their metabolic responses, offering insights for designing variety-specific feeding strategies to support sustainable aquaculture practices.