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Mandarin fish (Siniperca chuatsi) can adapt to artificial diets, with the improvement of domestication level. However, the effects of artificial diets on the muscle health of fish are unclear. In this study, 480 homogenous-sized mandarin fish (initial weight of 25.1 ± 0.1 g) were randomly divided into two groups and fed with artificial diets or live prey fish for eight weeks. The transcriptome sequencing analysis identified that artificial diets primarily affected glucose metabolism, lipid metabolism, and immune system in the muscle. Furthermore, artificial diets induced excessive glycogen accumulation in the muscle by increasing the mRNA expression of gluconeogenesis-related genes and decreasing the mRNA expression of glycolysis-related genes. Meanwhile, artificial diets significantly increased triglyceride accumulation in the muscle by upregulating the activity of fatty acid synthetase and the mRNA expression of lipid synthesis-related genes, including srebp1, fas, and plin2. Artificial diets significantly increased the level of malondialdehyde, leading to oxidative stress in the muscle. Besides, artificial diets also upregulated the mRNA expression of pro-inflammation cytokines, including il-1β, ifn-γ, and tnfα. In conclusion, artificial diets disrupted glucose and lipid metabolism and induced oxidative stress and inflammation in the muscle of mandarin fish.

This study investigated the effects of substituting fish meal (FM) in practical diet by chlorella meal on the growth, feed utilization, and flesh quality of Pacific white shrimp (Penaeus vannamei). First, a basal diet was prepared with 200 g/kg FM inclusion (FM-20), and then chlorella meal was used to reduce FM inclusion to 150 g/kg (FM-15), 100 g/kg (FM-10), 50 g/kg (FM-5), and 0 g/kg (FM-0), corresponding to the replacement levels of 25%, 50%, 75%, and 100% of dietary FM, respectively. Shrimp (1.37 ± 0.10 g) were fed with the five isonitrogenous and isolipidic diets for 56 days. No significant difference was observed in feed conversion ratio (FCR) and weight gain (WG) between FM-20 and FM-15 group (P>0.05), but when chlorella meal substituted 50% of dietary FM, WG, protein and lipid retention, and n-3/n-6 PUFAs in flesh were significantly reduced with significant increase in FCR (P0.05). When dietary FM was totally substituted by chlorella meal, the body yellowness and redness and essential amino acid content in flesh, including Lys and Met, were significantly reduced (P0.05). To sum up, in a practical diet with 200 g/kg FM inclusion, chlorella meal successfully replaced 25% of dietary FM without adverse impacts on the growth and feed utilization, and the substitution of 75% of dietary FM did not negatively affect the flesh quality of Pacific white shrimp.

The present study aimed to evaluate the dietary effects of Clostridium butyricum culture (CC) or sodium butyrate (SB) on the growth, feed utilization, serum indicators, intestinal histology and microbiota of largemouth bass (Micropterus salmoides). CC and coated SB (50%) were supplemented to a low fish meal diet (245 g/kg) (control diet) at the inclusion levels of 1 g/kg and 2 g/kg, to form five iso-nitrogenous and iso-lipidic diets (control, CC-1, CC-2, SB-1, and SB-2). Then, the five diets were fed to largemouth bass with initial body weight of 70.2 ± 0.1 g. After 8 weeks of feeding, dietary supplementation of 1 g/kg CC increased the weight gain (WG) by 7.4% (P 0.05), when compared to the control. The muscle composition was not significantly affected by the inclusion of CC or SB (P > 0.05). Dietary inclusion of CC or SB significantly reduced serum diamine oxidase activity and increased lysozyme activity (P

To investigate the impact of dietary inclusion of ferulic acid (FA) on growth performance, physiological and biochemical functions and hepato-intestinal health, three iso-nitrogenous and iso-lipidic diets supplemented with 0 mg/kg, 100 mg/kg, and 200 mg/kg FA were fed to Megalobrama amblycephala (9.75 ± 0.04 g) for 8 weeks. The growth performance, physiological and biochemical parameters, antioxidant capacity and the expression of genes were assessed on 4th and 8th week. The results indicated that 100 mg/kg FA inclusion significantly enhanced the weight gain rate (on week 4 and 8), feed intake (on 4th week), protein efficiency ratio (on week 8) and condition factor (on week 4) (P

The aim of this trial was to investigate the effects of dietary protein and lipid levels on growth performance and flesh quality of largemouth bass (Micropterus salmoides). A 3 × 3 two-factor design was used, including three crude protein levels of 46%, 50%, 54% (P46, P50, P54) and three crude lipid levels of 8%, 12%, 16% (L8, L12, L16). Thus, a total of nine diets (P46/L8, P46/L12, P46/L16, P50/L8, P50/L12, P50/L16, P54/L8, P54/L12 and P54/L16) were prepared and fed to large-size largemouth bass with initial body weight of 109.7 g for 84 days. At the same dietary protein level, weight gain rate (WGR), protein efficiency rate (PER), viscerosomatic index and polyunsaturated fatty acids (PUFAs) percent in flesh showed an increasing trend with increasing the dietary lipid level, while feed conversion ratio (FCR) showed a decreasing trend. At P46 and P50, whole fish crude protein, muscle crude protein, total collagen content, hardness, springiness, chewiness and shear force increased, and steaming loss and freezing loss decreased with increasing the dietary lipid level, while the above indicators showed an opposite trend at P54. At P50, the protein retention (PR) of 16% crude lipid group was significantly higher than that in the 8% and 12% crude lipid groups (P 0.05). The P50/L16 group showed the highest PER, PR, whole fish protein, muscle protein, total collagen, PUFAs, muscle hardness, springiness, chewiness, shear force and the lowest steaming loss. In conclusion, based on growth performance and flesh quality, the appropriate dietary protein and lipid requirements for large-size largemouth bass were 50% and 16%, respectively.

Yeast culture (YC) is a yeast-fermented product of enzymolysis soybean protein with plenty of small peptide and nucleotide. This study aimed to investigate the effects of YC as a substitute for fish meal (FM) on the growth, serum biochemical parameters, intestinal histology and microorganisms of hybrid snakehead (Channa argus ♂ × C. maculate ♀). In a basal diet containing 250 g/kg FM, YC was included at the levels of 0, 40, 80, 120 g/kg to replace 0, 29.5, 59.0 and 88.5 g/kg FM to form four isonitrogenous diets (CON, YC-40, YC-80 and YC-120). The four diets were fed to hybrid snakehead with initial body weight (9.2 ± 0.1 g) for 70 days. The results showed that there were no significant differences in weight gain (WG), feed conversion ratio, protein efficiency ratio (PER), protein retention (PR) and lipid retention (LR) among the three groups of CON, YC-40 and YC-80 groups (P > 0.05). However, the WG, PER, PR and LR in YC-120 group were significantly lower than those in the CON group (P 0.05). In serum biochemical parameters, superoxide dismutase activity and total antioxidant capacity in YC-40 and YC-80 groups were significantly increased, and total cholesterol content in YC-120 group was significantly decreased when compared to the control (P 0.05). Intestinal microbial analysis showed that the major intestinal microorganisms in all groups were Firmicutes, Spirochaetota, Proteobacteria and Actinobacteria. The relative abundance of Brevinema in YC-120 group was significantly higher than that in CON group (P

Yeast culture is a complex fermentation product consisting of fermentation substrate, yeast cells and their metabolites. This study investigated the potential of yeast culture in replacing fishmeal in the diet of yellow catfish (Pelteobagrus fulvidraco). First, a basal diet was formulated to contain 160 g/kg fishmeal (CON), and then the dietary fishmeal was decreased to 120, 80, 40 and 0 g/kg via yeast culture inclusion, respectively, to form another four isonitrogenous and isolipidic diets (YC-12, YC-8, YC-4 and YC-0). Yellow catfish (3.00 ± 0.10 g) were fed with the above five diets with triplicates per treatment and 40 fish per replicate. After 8 weeks of feeding, the weight gain (WG), protein efficiency rate and protein retention in the YC-12 group and the feed conversion ratio (FCR) in the YC-12 and YC-8 groups showed no significant differences to the CON group (p > 0.05), but the WG in the YC-8, YC-4 and YC-0 groups was significantly lower, and the FCR in the YC-4 and YC-0 groups was significantly higher than in the CON group (p < 0.05). In terms of the whole-body composition, only the crude lipid content in the YC-0 group decreased significantly (p < 0.05). Compared with the CON group, the aspartate aminotransferase and alanine aminotransferase activities and D-lactic acid content in the YC-0 group were significantly increased, and the total cholesterol content was significantly reduced (p < 0.05). The activities of catalase, superoxide dismutase, and alkaline phosphatase, as well as the content of complement C3 and immunoglobulin M, were significantly increased, while the MDA content was significantly reduced in the YC-12 and YC-8 groups (p < 0.05). There were no significant differences in the intestinal amylase and lipase activity among all the groups (p > 0.05), while the trypsin activity in the YC-12 and YC-8 groups, as well as the diamine oxidase in the YC-4 and YC-0 groups, were significantly higher than those in the CON group (p < 0.05). In the intestine histology, there was a significant decrease in the intestinal villus height in the YC-4 and YC-0 groups as well as in the villus width in the YC-0 group (p < 0.05). In the hepatopancreas histology, lipid droplets appeared in the YC-4 and YC-0 groups, and severe cell vacuolation was observed in the YC-0 group. As a summary, in a practical diet containing 160 g/kg fishmeal, yeast culture can effectively replace 40 g/kg fishmeal without negatively affecting the growth performance, nutrient utilization, serum immune and antioxidant, intestinal and hepatopancreas histology of yellow catfish.

The purpose of this study was to analyze the affecting mechanism of Chlorella sorokiniana meal replacing fish meal on the growth performance and immune function of Pacific white shrimp, Litopenaeus vannamei by transcriptomics analysis. In a control diet containing 560 g % /kg fish meal, chlorella was used to replace 0 %, 20 %, 40 %, 60 %, 80 % and 100 % of dietary fish meal to form six iso-nitrogenous and iso-lipidic diets (C0, C20, C40, C60, C80, C100). The six diets were fed to white shrimp (1.37 ± 0.02 g) for 8 weeks. Compared to the control group, the final body weight (FBW), specific growth rate (SGR) and feed efficiency (FE) of the C20 group were significantly improved (P 0.05). When the replacement level of fish meal by chlorella was ≥ 60 %, the FBW, SGR and FE of shrimp were significantly decreased (P

Abstract This study investigated the effects of yeast culture (YC) substituting fishmeal (FM) on growth, nonspecific immunity, intestinal and hepatopancreatic histology of Litopenaeus vannamei. Based on the control diet with an FM content of 200 g/kg, YC was used to decrease dietary FM to 200, 160, 120, and 80 g/kg (FM20, FM16, FM12, FM8), respectively. Then, the four diets were fed to shrimp (2.78 ± 0.10 g) for 8 weeks. The results indicated that the FM8 group had poorer weight gain and higher feed conversion ratio than the control (p .05). Protein and lipid retention in the FM12 and FM8 groups were decreased (p

The present study was conducted to evaluate the efficacy of phytogenic extract on growth and health of tilapia. Three experimental diets were designed as the basal diet (Con) and phytogenic extract (Flourishing, F) supplemented diets at 0.5 and 1 g/kg inclusion (F-1 and F-2), which the phytogenic additive was extracted from Eucommia ulmoides, Astragalus membranaceus, Lonicera japonica and Codonopsis pilosula. The three diets were fed to juvenile tilapia (14.0 ± 0.1 g) with 30 fish per cage, and three replicate cages from the three groups were placed in one indoor concrete pool (a total of three pools were used). After 8 weeks of feeding, the weight gain was significantly increased, and feed conversion ratio was decreased in F-2 group (P < 0.05) when compared to the control. Both levels of phytogenic extract significantly promoted the retentions of protein and lipid and the apparent digestibility coefficient of dry matter and protein (P < 0.05). The activity of superoxide dismutase and the levels of white blood cells, haemoglobin and glutamic pyruvic transaminase were also significantly increased by the supplementation of phytogenic extract (P < 0.05). The villus height in anterior intestine was significantly enhanced in F-1 and F-2 groups (P < 0.05). After challenging with Aeromonas hydrophila, the cumulative mortality was significantly declined in F-1 and F-2 groups (P < 0.05). In summary, the dietary supplementation of phytogenic extract at 1 g/kg feed could provide positive efficiency on growth, nutrient utilization, immunity, gut morphology and disease resistance of tilapia under the present conditions.

The present study aimed to investigate the dietary effects of replacing fishmeal (FM) with cottonseed protein concentrate (CPC) on the growth, flesh quality and gossypol residue of Pacific white shrimp (Litopenaeus vannamei). Based on a diet containing 560 g/kg FM, CPC was used to replace 0%, 20%, 40%, 60%, 80% and 100% of dietary FM with CPC inclusion of 0, 130.2, 260.4, 390.7, 521 and 651.3 g/kg, respectively (CPC0, CPC20, CPC40, CPC60, CPC80 and CPC100). Then, the six isoproteic diets were used to feed shrimp with initial body weight of 1.20 ± 0.05 g in low salinity water (0.5–1.0‰) for 56 days. The results showed that the growth performance of shrimp was not significantly affected by the replacement of 20%, 40% of dietary FM with CPC (P > 0.05). Compared to the control, the weight gain was decreased by 15.1%, 21.7% and 33.8% (P 0.05), 0.18（P

This study was conducted to investigate the effects of adding bile acids to low fishmeal diet on the growth, nutrient utilization and serum biochemical parameters of Pacific white shrimp, Litopenaeus vannamei. First, a positive and a negative control diet were formulated to contain 200 g/kg fishmeal (FM20) and 140 g/kg FM (FM14), respectively. Then, bile acids were added to FM14 diet at the inclusion levels of 75 (BA75), 150 (BA150) and 300 (BA300) mg/kg. The five isoproteic and isolipidic diets were fed to shrimp with initial weight of 1.09 ± 0.01 g for 56 days. The results showed no significant difference in survival among all the groups (>90 %). Compared to FM20 group, the weight gain (−12.9 %), body crude protein content, apparent digestibility of dry matter and protein, bile acid content in hepatopancreas and serum were decreased significantly, while feed conversion ratio (FCR) was increased by 0.17 in FM14 group (P 0.05), reaching the similar levels to FM20 group (P > 0.05). Especially, the FCR of BA150 group was significantly lower (−0.16) than that of FM14 group (P

This study investigated the effects of replacing soybean meal (SM), corn gluten meal (CGM), and fish meal (FM) with fermented soybean meal (FSM) on growth performance, flesh quality, and intestinal microbiota of largemouth bass. In a diet with 400 g/kg FM inclusion (FSM-0), FSM was used to substitute 120 g/kg SM, 120 g/kg SM + 80 g/kg CGM, and 65 g/kg FM at the inclusion of 100 g/kg (FSM-10-SM), 200 g/kg (FSM-20), and 100 g/kg (FSM-10-FM), respectively. Then, largemouth bass weighing 225.7 ± 2.6 g was fed the four diets for 60 days. The WG of FSM-20 group was increased by 11.8% (P

Citric acid is an organic acid extensively used in feed industry, and AZOMITE is a hydrated aluminosilicate compound rich in rare earth elements and trace mineral elements. This study investigated the supplemental effects of AZOMITE and citric acid individual or in combination on the growth performance, intestinal microbiota, morphology, digestive enzyme activity, serum indexes, and disease resistance of juvenile largemouth bass. Six diets were designed, including the control diet (CON) and the five additive-supplemented diets with the addition of 4 or 8 g/kg citric acid (CA4, CA8), 3 g/kg AZOMITE (A3), and their combined addition as 4 g/kg citric acid + 1.5 g/kg AZOMITE) (C4A1.5) and 8 g/kg citric acid + 3 g/kg AZOMITE (C8A3). Juvenile largemouth bass with initial body weight of 22.01 ± 0.09 g were fed the six diets for 56 days. The results revealed that the combined addition of 4 g/kg citric acid and 1.5 g/kg AZOMITE (C4A1.5) increased weight gain by 7.99% (P

The study investigated the effects of dietary sodium butyrate (SB) on the growth performance, nutrient utilization, intestinal histology, and microbiota of rainbow trout (Oncorhynchus mykiss). A high fishmeal diet and a low fishmeal diet were formulated to contain 200 g/kg or 100 g/kg fishmeal, respectively. Coated SB (50%) was supplemented to each of the diets at levels of 0, 1.0, and 2.0 g/kg to create 6 diets. The diets were fed to rainbow trout with initial body weight of 29.9±0.2 g for 8 weeks. Compared to the high fishmeal group, the low fishmeal group showed significantly lower weight gain (WG), intestine muscle thickness, and significantly higher feed conversion ratio (FCR) and amylase activity (P0.05). The supplementation of 2.0 g/kg SB in low fishmeal diet significantly increased the villus height, villus width, and muscular thickness, while the supplementation of 2.0 g/kg SB in high fishmeal diet also significantly increased the intestinal villus height (P0.05). In conclusion, the addition of SB in diets containing 100 or 200 g/kg fishmeal did not enhance the growth performance and nutrient utilization of rainbow trout, but improved intestinal morphology and changed intestinal microbial flora.

This study compared the growth, flesh quality and metabolomics of largemouth bass (Micropterus salmoides) fed trash fish and formula feeds. Trash fish (TF), self-made feed (SF) and commercial feed (CF) were prepared with crude protein levels of 172.2 g/kg, 503.5 g/kg and 504.1 g/kg (666.2 g/kg, 547.3 g/kg and 535.1 g/kg based on dry matter), respectively. Then, the three diets were fed to largemouth bass with an initial body weight of 75.0 ± 0.1 g for 12 weeks. SF and CF groups presented significantly lower feed intake (FI), feed conversion ratio (FCR) and higher protein efficiency ratio (PER) than TF group based on dry matter basis without affecting the weight gain (P < 0.05). The yellowness (b*) in dorsal muscle, flesh heat-insoluble collagen and free flavor amino acids contents in SF group were significantly higher (P < 0.05), while drip loss were significantly lower (P < 0.05) than those of TF group. Compared to TF group, SF and CF groups showed significantly higher flesh polyunsaturated fatty acids (PUFAs), n-3 PUFAs and n-6 PUFAs contents, flesh hardness, shear force and muscle fiber density (P < 0.05), and lower flesh total free amino acids, essential amino acids, muscle fiber diameter, intestine villus height and muscular thickness (P < 0.05). The serum total protein, triglyceride and cholesterol levels in SF group were significantly lower than those in TF and CF groups (P < 0.05). In the muscle metabolomics, 177 differential metabolites were detected between SF and TF groups, which mainly enriched in pathways as biosynthesis of amino acid, histidine metabolism, glycine, serine and threonine metabolism, etc. Conclusively, feeding largemouth bass with formula feeds improved flesh fatty acid profile and flesh texture without negative effects on the growth, but the flesh free amino acids contents were lower than the fish fed trash fish.

The study investigated the effects of replacing fish meal with cottonseed protein concentrate (CPC), Tenebrio molitor (TM) and Clostridium autoethanogenum protein (CAP) on physical pellet quality and growth, feed utilization of Pacific white shrimp (Litopenaeus vannamei). A control diet (FM) was designed to contain 200 g/kg fish meal, then, 60 g/kg CPC, TM and CAP were used to replace the same amount of fish meal, respectively, to form four diets by pelleting. After the evaluation of physical quality, the four diets were fed to shrimp with initial body weight of 7.72 ± 0.01 g for 6 weeks. The results indicated that pellet hardness and bulk density were significantly increased (P 0.05). In addition, the dissolution loss and powder content in CPC and CAP diets were significantly decreased (P 0.05). Hepatopancreas amylase activity in CPC and CAP groups was significantly higher than that in FM group (P 0.05). The hepatopancreas and intestinal histology were normal in all groups without obvious injury. In conclusion, in the pelleted feed containing 200 g/kg fish meal, the replacement of 60 g/kg fish meal with CPC and CAP improved the physical pellet quality and had no negative effects on growth performance and nutrient utilization, but the replacement of 60 g/kg fish meal with TM decreased the growth performance and nutrient utilization of Pacific white shrimp.

The study investigated dietary effects of replacing fish meal (FM) with Clostridium autoethanogenum powder (CAP) on growth, flesh quality and metabolomics of largemouth bass (Micropterus salmoides). The control diet contained 350 g/kg FM, and then dietary FM was decreased to 300 g/kg, 250 g/kg, 200 g/kg, 150 g/kg and 100 g/kg by CAP inclusion, respectively (FM-30, FM-25, FM-20, FM-15, FM-10). Then, the six diets were fed to largemouth bass with initial body weight of 110 g for 56 days. The high CAP inclusion (FM-10) decreased specific growth rate, flesh collagen, flesh hardness and increased feed conversion ratio (P

The purpose of this study was to develop the potential of cottonseed protein concentrate (CPC) and Clostridium autoethanogenum protein (CAP) in the diet of rainbow trout (Oncorhynchus mykiss) by evaluating the effects of substituting fishmeal with a CPC and CAP mixture on growth performance, nutrient utilization, serum biochemical indices, intestinal and hepatopancreas histology. In a basal diet containing 200 g/kg fishmeal (Con), the mixture of CPC and CAP (1:1) was used to reduce dietary fishmeal to 150, 100, 50 and 0 g/kg, to form five diets with the same crude protein and crude lipid contents (CON, FM-15, FM-10, FM-5 and FM-0). Then, the five diets were fed to rainbow trout (35.00 ± 0.05 g) for 8 weeks. The weight gain (WG) and feed conversion ratio (FCR) of the five groups were 258.72%, 258.82%, 249.90%, 242.89%, 236.57%, and 1.19, 1.20, 1.24, 1.28, 1.31, respectively. FM-5 and FM-0 groups showed significantly lower WG and higher FCR than the CON group (p < 0.05). In terms of whole-body composition, such as moisture, crude ash, and crude protein, no significant difference was observed among all the groups (p > 0.05), except that significantly higher crude lipid content was detected in the FM-0 group than in the CON group (p < 0.05). In the FM-5 and FM-0 groups, protein efficiency, protein retention, intestinal protease activity and amylase activity were significantly lower than in the CON group (p < 0.05). Compared to the CON group, the serum contents of glucose and total cholesterol in the FM-0 group as well as MDA in the FM-5 and FM-0 groups were significantly increased, and catalase, superoxide dismutase, and total antioxidant capacity were decreased (p < 0.05). In intestine and hepatopancreas histology, the intestinal villus height in the FM-5 and FM-0 groups and villus width in the FM-0 group were decreased significantly (p < 0.05), while no significant difference in hepatopancreas morphology was observed among all the groups except that some vacuolization was observed in the FM-0 group (p > 0.05). In summary, the mixture of CPC and CAP can effectively replace 100 g/kg fishmeal in a diet containing 200 g/kg fishmeal without adverse effects on the growth performance, nutrient utilization, serum biochemical, or intestinal and hepatopancreas histology of rainbow trout.

This study investigated the effects of replacing fish meal (FM) with fermented soybean meal (FSM) on the growth performance, serum biochemical indices, intestinal health, microbial community and disease resistance of largemouth bass (Micropterus salmoides). The basal diet was designed to contain 350 g/kg FM (control, FSM-0), and then, FM was decreased to 300 g/kg, 250 g/kg, 200 g/kg, 150 g/kg by the FSM inclusion of 75 g/kg (FSM-7.5), 150 g/kg (FSM-15.0), 225 g/kg (FSM-22.5) and 300 g/kg (FSM-30), respectively. The five diets were fed to largemouth bass with initial body weight of 21.2 ± 0.1 g for 8 weeks. The results showed that FSM-30 group presented lower weight gain, and FSM-22.5 and FSM-30 groups displayed higher feed conversion ratio than those of the control group (P 0.05). Compared with the control, the protein retention in FSM-30 group, the lipid retention in FSM-15, FSM-22.5 and FSM-30 groups, and serum superoxide dismutase activity and total antioxidant capacity in FSM-22.5 and FSM-30 groups were decreased (P

Clostridium autoethanogenum protein (CAP) is a new single-cell protein explored in aquatic feeds in recent years. This study investigated the dietary effects of CAP replacing fishmeal (FM) on the growth, intestinal histology and flesh metabolism of largemouth bass (Micropterus salmoides). In a basal diet containing 700 g/kg of FM, CAP was used to substitute 0%, 15%, 30%, 45%, 70% and 100% of dietary FM to form six isonitrogenous diets (Con, CAP-15, CAP-30, CAP-45, CAP-70, CAP-100) to feed largemouth bass (80.0 g) for 12 weeks. Only the CAP-100 group showed significantly lower weight gain (WG) and a higher feed conversion ratio (FCR) than the control (p < 0.05). A broken-line analysis based on WG and FCR showed that the suitable replacement of FM with CAP was 67.1–68.0%. The flesh n-3/n-6 polyunsaturated fatty acid, intestinal protease activity, villi width and height in the CAP-100 group were significantly lower than those in the control group (p < 0.05). The Kyoto Encyclopedia of Genes and Genomes analysis showed that the metabolic pathway in flesh was mainly enriched in the “lipid metabolic pathway”, “amino acid metabolism”, “endocrine system” and “carbohydrate metabolism”. In conclusion, CAP could successfully replace 67.1–68.0% of dietary FM, while the complete substitution decreased the growth, damaged the intestinal morphology and down-regulated the lipid metabolites.

Micropterus salmoides is one of the most economically valuable fish species in China. Currently, information in the effect of probiotics-supplemented feed on M. salmoides is rare. Present study investigated the impact of supplementary Lactobacillus casei K17 with six treatments on growth performance, gut digestion, absorption and non-specific immune, and gut bacterial biota and metabolomics of M. salmoides. A total of 450 M. salmoides (114 day of age, average 33.0 ± 0.5 g) were randomly allocated into six groups for a 69-day rearing experiments. M. salmoides was given commercial feed supplemented with: 1) live L. casei K17 (1 × 109 CFU/g), 2) live L. casei K17 protected by skim milk powder (10 %), 3) heat-killed dead L. casei K17, 4) its fermentation supernatant, 5) skim milk powder (10 %), and 6) normal saline (0.85 % NaCl), designated as LB, MB, DB, FS, MG, and SG, respectively. MB and DB diets significantly increased body weight and growth rate, but decreased feed conversion ratio of M. salmoides (p

Nuclear factor erythroid 2-related factor 2 (Nrf2) is an important transcription factor in the regulation of redox homeostasis, which plays a vital role in metabolism, the cell cycle, and cell protection. In this study, the complete cDNA sequence of Nrf2 gene of grass carp was obtained by rapid amplification of cDNA ends-polymerase chain reaction (RACE-PCR), and the characteristics of Nrf2 proteins predicted from gene sequencing were analyzed by bioinformatics methods. Tissue differential expression patterns were also detected by Real-time Fluorescence quantitative PCR (qRT-PCR). Then, Eucommia ulmoides (EU), a traditional Chinese medicine, was added into diet with an inclusion of 2% to feed grass carp for 3 months to investigate the effects on the expression of Nrf2 gene in tissues. The results showed that the full-length of Nrf2 gene of grass carp is 2760 bp, encoding 593 amino acids, and the predicted Nrf2 protein is a hydrophilic and non-secretory protein. Grass carp Nrf2 gene showed higher expression in kidney, gill, liver, spleen, and blood tissues than in other tissues. In the feeding trial, dietary EU significantly promoted the Nrf2 mRNA expression in kidney, gill, and liver tissues after three months feeding. The results suggest that Nrf2 plays an important role in the anti-oxidative capacity of grass carp and its expression is enhanced by dietary EU. Keywords: Grass carp, Nrf2, RACE, Bioinformatics analysis, Eucommia ulmoides

Two trials were conducted to evaluate the effects of positively buoyant dietary materials on growth, intestinal health, and fecal properties of tilapia. In trial 1, ten diets containing 0 (control) 1%, 2% or 3% cork, expanded and vitrified microball or expanded vermiculilite fine particles (250–450 μm) were fed to tilapia fry (5.0 ± 0.1 g) for 30 days to evaluate the effects on the growth and feeding efficiencies. In trial 2, the three buoyant materials with coarse particles (450–830 μm) were included in diets at 0 (control), 3%, 4% or 5% supplementation levels to feed tilapia juveniles (55.0 ± 1.0 g), and the growth, feed efficiencies, evacuation velocity, fecal floatability and intestinal histology were examined after 21 days feeding. In trial 1, the weight gain (WG) of the fish significantly decreased with the supplementation of 2%, 3% cork, 3% microball or 3% vermiculite (P

We previously demonstrated that Lactobacillus casei K17, isolated from Korean kimchi, has high antioxidant levels in vitro and in vivo. However, its effect on Micropterus salmoides is unknown. In this study, we investigated the impact of L. casei K17 supplementation on the lipid metabolism, antioxidant response, liver histology, and fillet quality of M. salmoides. We randomly assigned 450 M. salmoides (33.0 ± 0.5 g) to six diet groups for 69 days. The diets were as follows: 0.85% normal saline; 10% skim milk powder; 1 × 108 CFU/g live L. casei K17 (LB); 1 × 108 live L. casei K17 protected by skim milk powder (MB); 1 × 108 dead L. casei K17 (DB); and L. casei K17 fermentation supernatant. MB significantly improved the crude protein, total collagen, alkaline-insoluble collagen, fiber numbers, hardness, chewiness, and gumminess of M. salmoides fillets (p < 0.05). LB significantly improved crude protein and fiber numbers (p < 0.05). Furthermore, dietary supplementation with LB, MB, and DB maintained normal liver histology, preserved liver function, and increased hepatic and hemal antioxidant status by enhancing antioxidant enzyme activities. Meanwhile, the three diets also promoted lipid metabolism by increasing HDL-C effectiveness and reducing total cholesterol, triglyceride, and low-density lipoprotein cholesterol levels in serum and liver tissues, indicating that dietary supplementation with DB, LB, and MB had hypolipidemic effects on M. salmoides. MB and LB significantly improved fillet quality and LB, MB, and DB improved hemal and hepatic lipid metabolism and antioxidant response and reduced reactive oxygen species production, protecting M. salmoides hepatic cells from injury.