Aquaculture Nutrition最新文献

Nile tilapia, Oreochromis niloticus, (2.00 ± 0.02 g) were reared in 16 70-L tanks (40 individual/tank) and fed diets (approx. 345 g/kg protein, approx. 87 g/kg crude fat) containing 0 (CTL), 75 (PH-75), 150 (PH-150), and 300 (PH-300) mg/kg phytol (n = 4). After 60 days of feeding (4% daily), growth performance, humoral immune parameters, and gut bacteria were analyzed. Also, hepatic antioxidant parameters were determined before and after the fish were transported in plastic bags for 6 hr. The results showed that PH-75 exhibited the highest final weight (P < 0.001), weight gain (P < 0.001), feed intake (P < 0.001), feed efficiency (P = 0.015), plasma lysozyme activity (P = 0.004), and intestinal Lactobacillus sp. population (P = 0.017), among the treatments. The highest plasma alternative complement activity (P = 0.006) and the lowest intestinal total viable bacteria (P = 0.027) were observed in PH-75 and PH-150. The highest plasma alkaline phosphatase activities were observed in PH-75 and PH-300 (P = 0.014). The highest blood leukocyte (P = 0.008), monocyte (P = 0.010), and eosinophil (P < 0.001) were observed in PH-300, while the highest blood neutrophil was observed in all phytol treatments (P < 0.001). The highest hepatic lipid peroxidation was observed in PH-300, whereas PH-75 and PH-150 showed the lowest values (P < 0.001). The highest hepatic reduced glutathione was observed in PH-75, also PH-150 exhibited significant elevation in this parameter, compared to CTL (P < 0.001). Transportation led to significant elevations in the hepatic antioxidant enzymes’ activities in CTL, PH-75, and PH-150; the highest activities were related to PH-75 and PH-150 treatments, which had also the highest post-transportation survivals (P < 0.001). In conclusion, phytol is a suitable feed supplement for Nile tilapia, improving growth performance and welfare, particularly at 75 mg/kg.

Lysophospholipids (LPLs) and bile acids (BA) are commonly used as emulsifiers in aquaculture. This study investigated the effects of dietary supplementation of LPLs or BA on the growth performance, lipid deposition, and intestinal health of largemouth juveniles. Fish were randomly allotted into three groups in quadruplicate and fed with a basal diet (CON) or diets containing 300 mg/kg LPLs (LPLs), or 300 mg/kg commercially available BA product (BA) for 8 weeks. The results showed that compared with the control group, LPLs and BA supplemented groups showed a higher weight gain trend, and LPLs supplementation promoted the protein deposition in fish body. Both BA and LPLs supplementations helped to maintain liver health by decreasing the activities of aspartate aminotransferase and alanine aminotransferase in serum. Besides, LPLs supplementation decreased overall lipid deposition in terms of mesenteric fat index and liver lipid content. Furthermore, LPLs supplementation showed unique advantage in improving intestinal barrier, as characterized by the increased villus length and higher expression of the tight junction protein zo-1 expression. LPLs supplementation also increased the alpha diversity index and the abundances of Proteobacteria in the intestinal microbiota which is positively correlated with the abundance of SCFA in the gut. These findings will promote the application of novel feed additives and especially provide a basis for the rational selection of emulsifiers in the aquaculture industry.

In previous study, we found that the cholesterol requirement of Eriocheir sinensis was 0.27%, to further investigate the effects of cholesterol on health status, ovarian maturation, and lipid metabolism of female Eriocheir sinensis broodstock. Two diets containing 0% and 0.25% (actually 0.05% and 0.27%) cholesterol were fed to the female crabs (average weight: 49.21 ± 0.11 g) for 4 months and sampled once a month. The results showed that the body weight (BW), survival rate (SR), meat yield (MY), condition factor (CF), hepatosomatic index (HSI), and gonadosomatic index (GSI) of Eriocheir sinensis were significantly affected by treatment time and compared with the cholesterol deficient group, supplementing cholesterol significantly increased BW, HSI, and GSI (P < 0.05). In addition, long-term lack of cholesterol will lead to a significant decrease in the activity of ACP, AKP, and SOD and a significant increase in the content of MDA. The histological results showed that cholesterol significantly increased the volume of oocytes (P < 0.05). Further studies found that 0.27% cholesterol significantly increased the transcription levels of vtg and vgr in hepatopancreas and ovaries, which may be the main reason for the increase of oocyte size (P < 0.05). When fed with 0.27% cholesterol diet, the contents of nutrients in hepatopancreas and ovaries increased significantly, especially lipids and cholesterol (P < 0.05). Through the analysis of mRNA expression level of genes related to lipid metabolism, it was found that cholesterol enhanced the transcription level of genes related to lipid synthesis and transport in hepatopancreas, thereby promoting the accumulation of lipid in the organism. Furthermore, compared with control group, the levels of juvenile hormone (JH), 17β-estradiol (E₂), methyl farnesoate (MF), and ecdysone in the organism were significantly increased after feeding a diet with 0.27% cholesterol (P < 0.05). In summary, supplementing an appropriate amount of cholesterol in the diet can improve the growth performance of Eriocheir sinensis broodstock, enhance the body’s antioxidant and immune system, and promote the accumulation of nutrients in the ovaries, thereby promoting ovarian maturation.

A 60-day feeding trial was conducted to evaluate the impact of dietary Antarctic krill meal on the reproductive performance and embryo quality of the Chinese mitten crab, Eriocheir sinensis. Three diets were formulated, incorporating varying levels of Antarctic krill meal at 0% (Diet K0), 10% (Diet K10), and 20% (Diet K20), with a control group fed razor clam Sinonovacula constricta. Each diet was randomly assigned to three replicate tanks, each stocked with 5 males and 10 females. Male and female weights were 145.38 ± 8.01 and 102.57 ± 9.73 g, respectively. The results revealed no significant differences in weight gain rate, specific growth rate, and survival rate. However, the hepatopancreatic weight and hepatopancreas index of female crabs in each group decreased, while gonadal weight and gonadosomatic index increased significantly after 60 days, with Diet K20 showing the highest values. Egg production and fecundity of female crabs reached their peak in Diet K20, with no significant differences in reproductive indices among all groups. The phospholipid content in Diet K20 was significantly higher than in the other groups (P < 0.05). Cholesterol contents in Diet K0 and the control group were significantly higher than in Diet K10 and K20 (P < 0.05). No significant differences were observed in egg diameter, egg weight, moisture, crude protein, and crude fat between the groups. The content of C20 : 2 and C20 : 4n6 was highest in Diet K0, with a significant difference compared to Diet K10 (P < 0.05). However, no significant differences were found in the total content of saturated fatty acids, monounsaturated fatty acids, and polyunsaturated fatty acids among all groups. Based on the research findings, it is recommended that the optimal level of Antarctic krill meal in diets is 20%.

Seven graded levels of sodium propionate (SP) diets with 0 (SP1), 0.2% (SP2), 0.4% (SP3), 0.6% (SP4), 0.8% (SP5), 1.0% (SP6), and 1.2% (SP7) were prepared to feed Trachinotus ovatus (initial body weight: 8.64 ± 0.08 g) for 56 days. The results showed that increasing dietary SP levels quadratically increased significantly final body weight (FBW), weight gain rate (WGR), and specific growth rate (SGR) of T. ovatus but linearly and quadratically decreased significantly viscerosomatic index (VSI) and hepatosomatic index (HSI) of T. ovatus (P < 0.05). In the SP4 treatment, FBW, WGR, and SGR presented the highest values. Both positive linear and quadratic trends were detected between crude lipid content of whole fish, adhesiveness of dorsal muscle, white blood cell (WBC), red blood cell (RBC), hemoglobin (HGB), blood performance, high-density lipoprotein cholesterol (HDL-c), intestinal villus height, and dietary SP level, while negative linear and quadratic trends were found between firmness of dorsal muscle, triglyceride (TG), glucose (GLU), and dietary SP level (P < 0.05). The increasing SP led to quadratic increases in lymphocyte (Lym), complement 3 (C3), chymotrypsin, villus number, and muscle layer thickness, and a quadratic decrease in hepatic malondialdehyde (MDAP < 0.05). A significant negative linear trend was found between the content of glutamic-pyruvic transaminase (GPT) and dietary SP level, while significant positive linear trends were presented between C4, immunoglobulin M (IgM), α-amylase and dietary SP level (P < 0.05). The increasing SP resulted in linear and quadratic increases in superoxide dismutase (SOD), total antioxidant capacity (T-AOC) of livers and C3, C4, IgM of head kidney (P < 0.05). The expression levels of tumor necrosis factor alpha (TNF-α) and interleukin-8 (IL-8) were linearly and quadratically decreased, while the mRNA levels of growth factor beta (TGF-β) were linearly and quadratically increased with the increasing SP level (P < 0.05). In conclusion, SP could be considered as a beneficial feed additive for enhancing growth and immunity of fish. And dietary SP level at 0.6% is optimal for the growth of Trachinotus ovatus based on a quadratic regression model of WGR.

The effects of plant protein sources (PPSs) on the health of the liver and intestine of the largemouth bass, Micropterus salmoides, were compared to verify the potential damaging effects of dietary fiber (DF). A diet containing 55% fish meal (FM) was used as the control. The test diets contained 25% soybean meal (SBM), rapeseed meal (RSM), cottonseed meal, or peanut meal, and the FM content was decreased to 30%. The protein and lipid contents of these five diets were balanced by casein and oil. Fish were raised for 8 weeks. The fish fed the diet containing PPS showed a trend of decreasing growth and apparent digestibility coefficients. The contents of total bile acid, lipid, and collagen in the liver were increased, and the mRNA expression levels of genes encoding inflammatory factors and enzymes involved in de novo fatty acid synthesis and bile acid synthesis were upregulated. Both the lipid and collagen contents in the liver were positively correlated with the DF content in the diet significantly. Morphology and histology showed reduced liver size, hepatic steatosis, and fibrosis in fish fed diets containing PPS. The lowest hepatosomatic index was observed in fish fed the SBM diet, and the most severe damage was observed in fish fed the RSM diet. No obvious histological abnormalities were observed in the hindgut. The bile acid profile in the liver could be used to distinguish the types of PPS very well by Fisher discriminant analysis. These results indicated that 25% of each of the four PPSs in the diet exceeded the tolerance range of largemouth bass and caused liver damage, which might be mediated by bile acid. DF in PPS might be an important agent contributing to liver damage.

A 56-day feeding trial assessed the effects of black soldier fly larvae meal (BSFLM) on the growth performance and hepatopancreas health of juvenile Eriocheir sinensis. Six isoproteic and isolipidic diets with 0% (FM), 10% (BSFLM10), 20% (BSFLM20), 30% (BSFLM30), 40% (BSFLM40), or 50% (BSFLM50) replacement of fish meal by BSFLM were formulated. Compared to FM, replacing 10%–40% of fish meal with BSFLM did not significantly affect the weight gain rate (WGR) or specific growth rate (SGR), while BSFLM50 significantly decreased the WGR and SGR. Crabs fed BSFLM50 had significantly lower T-AOC activity than those fed other diets, and crabs fed BSFLM30, BSFLM40, or BSFLM50 had significantly lower activities of antioxidant enzymes (SOD and GSH-Px) in the hepatopancreas than those fed FM or BSFLM10. Compared to FM, BSFLM10, BSFLM20, and BSFLM30 did not affect the relative expression of genes related to the nonspecific immunity, while BSFLM40 and BSFLM50 upregulated the relative expression of these genes. Furthermore, histological analysis showed that the hepatopancreas was deformed in the BSFLM50 group, with widened lumens and loss of basal membrane integrity. In summary, BSFLM replacing 50% of fish meal reduced growth and structural damage to the hepatopancreas. An immune response was activated when the replacement level was over 30%. Therefore, the replacement level of dietary fish meal by BSFLM is recommended to be not more than 30% of the juvenile E. sinensis feed.

The present study explored the effects of inositol on growth performance, body composition, antioxidant performance, and lipid metabolism of largemouth bass (Micropterus salmoides). Six isonitrogenous and isolipidic diets containing 0 mg/kg (G1, control), 125 mg/kg (G2), 250 mg/kg (G3), 375 mg/kg (G4), 500 mg/kg (G5), and 625 mg/kg (G6) inositol were prepared and fed to cultured fish (initial weight: 110 ± 1 g) for 8 weeks in recirculating the aquaculture systems. The results indicated that compared with G1 group, the weight gain rate (WGR), specific growth rate (SGR), and feed efficiency rate (FER) in the G3 group were significantly higher. The crude lipid content of the whole fish and the liver of cultured fish was significantly reduced with increasing dietary inositol inclusion. However, no significant effects on moisture, crude protein, and ash contents of fish were observed among the different groups. Dietary inositol supplementation significantly increased muscular crude protein. However, muscular total lipid contents were decreased when the inclusion level was higher than 250 mg/kg (G3–G6 groups). As dietary inositol supplemental level increased, serum triglyceride (TG), and cholesterol (TC) contents showed an increasing trend and reached the maximum value in the G3 group. Additionally, serum low-density lipoprotein cholesterol (LDL-C) in G2, G3, G4, and G5 groups was significantly upregulated by increasing inositol. While, there was no significant change in serum high-density lipoprotein cholesterol (HDL-C) among the treatments. Inositol inclusion also significantly reduced the serum alkaline phosphatase (AKP), glutamic–pyruvic transaminase (ALT), and glutamic–oxaloacetic transaminase (AST) activities as well as serum malondialdehyde (MDA) content but significantly increased serum catalase (CAT), superoxide dismutase (SOD) activities, and total antioxidant capacity (T-AOC). Compared with the control group, the activities of hepatic total lipase (TL) and lipoprotein lipase (LPL) were significantly elevated in the G3, G4, and G5 groups. Above all, dietary inositol supplementation could improve growth performance and antioxidant capacity, and reduce the liver fat content of largemouth bass, and the optimal supplementation level of inositol in feed is estimated to be 250.31–267.27 mg/kg.

We investigated the effects of dietary tannic acid (TA) supplementation of a high-carbohydrate diet on growth, feed utilization, whole-body proximate composition, serum biochemical indicators, antioxidant capacity, digestive enzyme activity, and liver and intestinal health of juvenile largemouth bass, Micropterus salmoides (initial mean weight: 8.08 ± 0.08 g). Five diets were prepared, including a positive control (dietary carbohydrate level, 16%, LC0), a negative control (dietary carbohydrate level, 21%, HC0), and three TA-supplementation diets based on the negative control diet with TA addition at 200, 400, and 800 mg/kg, respectively. After 8 weeks of feeding, the results showed that compared with the LC0 diet, 400–800 mg/kg dietary TA significantly improved the survival rate of largemouth bass (P < 0.05) while significantly reducing its weight-gain rate and specific growth rate (P < 0.05). Compared with the HC0 diet, 400 mg/kg dietary TA significantly increased serum catalase activity (P < 0.05), and significantly decreased serum malondialdehyde, liver glycogen, lightness (L ^∗), and yellowness (b ^∗) (P < 0.05). Moreover, compared with the HC0 diet, 200–400 mg/kg dietary TA effectively improved the vacuolation of hepatocytes caused by the high-carbohydrate diet and reduced the occurrence of intestinal epithelial cell vacuolation and necrosis. In turn, 800 mg/kg dietary TA significantly inhibited protease activity in the pyloric caecum and intestine (P < 0.05). In conclusion, dietary supplementation with TA inhibited protease activity, which resulted in decreased growth performance in largemouth bass. However, it was also found that 200–400 mg/kg TA enhanced the antioxidant capacity of largemouth bass in the case of the high-carbohydrate diet, reduced liver glycogen levels, and improved liver and intestinal health. Finally, it should be noted that, when the dietary TA level exceeded 800 mg/kg, TA appeared to play a pro-oxidation role in the liver, which may cause oxidative stress in the liver.