Search

The intestinal tract plays an important role in digestion and absorption, nutrient metabolism, and immune anti-stress. At the same time, the intestine is also the major site for pathogens and various harmful substances to invade. Probiotics, as living microbial agents, improve animal health by maintaining the microecological balance of the host's intestinal flora. To explore the protective effect of Clostridium butyricum (CB) on the gut, we investigated the changes in digestion, antioxidant, and gut microbiota in juvenile largemouth bass. The fish were fed with diets containing 0 (control, CB0), 4.3×108 (CB1), 7.5×108 (CB2), 1.5×109 (CB3), and 3.2×109 (CB4) CFU/kg Clostridium butyricum for 56 days. After 56 days of dietary supplementation with 4.3×108 and 3.2×109 CFU/kg of CB, significant growth promotion and feed utilization improvement were observed in largemouth bass (P < 0.05). The activities of digestive enzymes (trypsin, protease and amylase) and intestinal functional indicators (sodium-potassium ATP, γ-GT and CK) were significantly increased in the intestine of largemouth bass (P < 0.05). The contents of intestinal short-chain fatty acids (acetic acid, propionic acid, isobutyric acid, N-butyric acid and isovaleric acid) in largemouth bass were significantly increased (P < 0.05). CB significantly increased the activities of antioxidant enzymes (T-AOC, CAT, POD, GSH-Px and SOD) and decreased the content of MDA in the intestine of largemouth bass (P < 0.05). It was also observed that CB significantly increased the activities of immune-related markers lysozyme and alkaline phosphatase (P < 0.05). High-throughput sequencing of the 16 S rRNA gene in largemouth bass revealed a significant increase in gut microbial richness. KEGG pathway analysis showed that CB had significant effects on intestinal microbiota functions, such as nutrient metabolism and energy conversion. The results showed that CB could stimulate intestine to produce the organic product butyric acid, which was customized in the gut to enhance digestive performance, promote nutrient metabolism, and protect microbial homeostasis in the intestinal tract of largemouth bass. These results provide new insights into the protective effects of CB on the intestinal tract of aquatic animals.

The aim of this study was to investigate the effects of arginine supplementation on liver morphology, antioxidant capacity, inflammatory response, insulin signaling pathway and glucose metabolism in hybrid snakehead. Five experimental diets (2.31 %, 2.42 %, 2.72 %, 2.92 %, and 3.12 % arginine) were prepared by adding different levels of arginine to the basal diet containing high (27 %) level of carbohydrate. The results showed that the activities of superoxide dismutase (SOD), catalase (CAT), peroxidase (POD) and glutathione peroxidase (GSH-Px) of fish fed with arginine diets were significantly higher than those in control group (p

The effects of dietary tributyrin (TB) on growth, intestinal health, inflammatory response and antioxidant status in juvenile Pelteobagrus fulvidraco were investigated. The fish (initial weight 5.53 ± 0.02 g) were fed with diets containing 0 (control, TB0), 500 (TB1), 1000 (TB2) and 2000 (TB3) mg/kg tributyrin for 56 days. The results showed that significantly higher final weight, specific growth rate, protein efficiency ratio and protein retention were observed in fish fed with TB2 diet compared with those in TB0 (P

A 100-d feeding trial was conducted to evaluate the effects of replacing soybean meal (SBM) and rapeseed meal (RSM) with faba bean meal (FBM) on growth performance and muscle quality of tilapia. A total of 600 fish (initial body weight 500.2 ± 0.34 g) were randomly distributed into 4 groups with 3 replicates per group and 50 fish per replicate. Four diets were formulated to replace SBM and RSM with FBM at the rate of 0 % (R0), 25 % (R25), 50 % (R50) and 100 % (R100). Results showed that FBM substitute diets did not significantly alter (P > 0.05) the weight gain rate, specific growth rate, feed conversion ratio, feed intake and viscerosomatic index, but increased (P 0.05) essential amino acids, but increased (P

The effects of arginine on intestinal shape, digestive enzyme activity, antioxidant capacity, and intestinal flora of hybrid snakeheads Channa maculata♀×Channa argus♂. Five experimental diets were formulated to contain arginine with 2.31%, 2.42%, 2.72%, 2.92%, and 3.12% respectively, and recorded as G1 (control), G2, G3, G4, and G5. Five groups of 50 fish (22.02 ± 0.02 g) for each diet were fed to apparent satiation twice daily for 56 days. The results showed that significantly higher weight gain (WG), specific growth rate (SGR), protein deposition rate (PDR), intestinal somatic indices (ISI), lipase, trypsin, Na+/K+-ATPase, γ-glutamyl transpeptidase, and significantly lower feed coefficient rate (FCR) were observed in fish fed with 2.92% diet compared to 2.31% group (P

The experimental trial was conducted to assess the effects of dietary pyridoxine on growth performance, physiological metabolics, intestinal enzymatic activities and antioxidant properties of Pelteobagrus fulvidraco. Six isonitrogenous and isolipidic diets (420 g/kg protein and 70 g/kg lipid) were formulated to contain 3.69 (control), 5.45, 7.31,11.17, 19.43 and 33.94 mg/kg pyridoxine. Four groups of 30 fish (3.85 ± 0.01 g) per tank (300-L cylindrical fiberglass tanks) for each diet were fed to apparent satiation twice daily for 63 days. Blood, intestine and hepatopancreas samples were obtained for metabolic, enzymatic activities and antioxidant properties analyses. The results showed that significantly higher weight gain (WG), specific growth rate (SGR), protein efficiency ratio (PER), protein retention efficiency (PRE), whole-body crude protein, intestinal protease, alkaline phosphatase, Na+/K+-ATPase, γ-glutamyl transpeptidase and significantly lower feed conversion ratio were observed in fish fed diet with 7.31 mg/kg compared to those in control group (P

Low-salinity tolerance and growth are crucial economic traits of shrimp in areas with low-salinity water. In the current study, an F1 full-sib family of Pacific white shrimp (Litopenaeus vannamei) was obtained by the “semidirectional cross” method, and 2 parents and 146 progenies were genotyped using double-digest restriction site-associated DNA sequencing technology (ddRAD-Seq). A total of 3335 high-quality markers were identified and used to construct a genetic linkage map. This genetic map comprised 48 linkage groups (LGs), and the total map length spanned 3954.462 centimorgan (cM) with an average marker interval of 1.186 cM. Three quantitative trait loci (QTLs) for low-salinity tolerance and 3 QTLs for growth (body weight) were detected under the condition of restricted logarithmic odds (LOD) score ≥ 2.50. With the assistance of the genome of L. vannamei and relevant annotations, 3 potential growth-related genes (sob, TJP1 and ZBTB24) and 3 low-salinity response candidate genes (Rnf168, CNOT2 and RPB3) were identified from the genomic scaffolds. Moreover, the qPCR results showed that the expression levels of the 3 candidate genes were significantly affected by low-salinity stress, indicating that they possibly play an important role in low-salinity stress. Here, we present the first report of mapping of low-salinity tolerance QTLs in the genetic mapping of L. vannamei, which will be beneficial for the selection of shrimp breeding markers and might help promote the study of the L. vannamei genome.

Although effects of dietary condensed tannins (CT) on growth and health of fish have been evaluated, limited information is available on shrimp. This study investigated the effects of CT on growth, nutrient digestibility, antioxidant response and intestinal histomorphology of Litopenaeus vannamei. A 56-day feeding trial was conducted by randomly distributing 600 shrimp into 15 tanks with 40 shrimp per tank and fed five diets containing 0 (G0), 0.5 (G0.5), 1 (G1), 2 (G2) and 4 (G4) g/kg of grape seed CT respectively. Shrimp were fed to apparent satiation during the entire feeding trial and feces were collected daily for the last 14 days to determine nutrient digestibilities. Hepatopancreas and intestine samples were collected to analyze antioxidant-related genes expression and histomorphology. Results indicated that dietary CT linearly increased final body weight, weight gain rate and specific growth rate (0.05 0.05). As compared with G0, dietary CT increased superoxide dismutase (G0.5, G1 and G2), glutathion peroxidase (G1 and G2) and nuclear factor erythroid 2-related factor 2 (G0.5, G1, G2 and G4) mRNA levels (P

Condensed tannins (CT) have been observed to be beneficial to maintain glucose homeostasis and improve carbohydrate utilization for livestock, whereas little information is available about the effects of CT on glycometabolism of fish. Three diets were formulated to contain approximately 15 % carbohydrate (G1), 39 % carbohydrate (G2), and G2 supplemented with 0.1 % CT. A total of 225 juvenile Lateolabrax japonicus were randomly assigned to 3 groups (triplicate tanks per group) with 25 fish in each tank and fed to apparent satiation during 56-d feeding trial. Results indicated that fish fed G2 had lower (p < 0.05) final body weight, weight gain rate, feed intake, specific growth rate and serum insulin concentration, but higher (p < 0.05) feed efficiency ratio and serum glucose, total antioxidant capacity, superoxide dismutase, immunoglobulin M and lipopolysaccharide than those fish fed G1 or G3. The activity of pyruvate kinase (PK) was lower (p < 0.05) but glucokinase (GK) was higher (p < 0.05) in G2 than in G1 or G3. Gene expression of insulin like growth factor Ⅰ and PK were down-regulated (p < 0.05), whereas GK was up-regulated (p < 0.05) in G2 than in G1 or G3. No difference (p> 0.05) in these gene expressions were observed between G1 and G3. It was concluded that L. japonicus fed diet with 39 % carbohydrate exhibited depressed growth performance, increased antioxidant and immune capacity, and hyperglycemia. Supplementation of 0.1 % CT resulted in improved growth performance and decreased serum glucose concentration, mainly due to the positive effects of CT on the activity and gene expression of hepatic glycolysis and gluconeogenesis enzymes of L. japonicus.