We aimed to investigate the effect of xylooligosaccharides (XOS) on the growth performances and lipid metabolism of common carp fed high-fat diets. 192 fish were randomly distributed into 24 tanks into six groups (four replicates) and were fed with control diet, high-fat diet (HFD) and HFD supplemented with 5, 10, 20 and 30 g/kgXOS respectively for 8 weeks. Fish fed HFD supplemented with 10 g/kg XOS obtained higher final body weight, weight gain, specific growth rate and protein efficiency ratio compared to those fed control diet and HFD, while feed conversion ratio showed the opposite trend. Fish fed HFD obtained higher hepatosomatic index, abdominal fat, energy intake compared to other groups, whereas the opposite was true for nitrogen retention. High plasma levels of cholesterol, triglycerides, low-density lipoprotein and low high-density lipoprotein were observed in fish fed HFD; opposite was true for fish fed HFD supplemented with 10–20 g/kg XOS. The transcription of lipoprotein lipase was up-regulated, whereas that of carnitine palmitoyltransferase I, peroxisome proliferator-activated receptors alpha, acyl-CoA oxidase and CD36 were down-regulated in fish fed HFD. Opposite trend was observed in fish fed HFD supplemented with 10–20 g/kg XOS as well as the control group. In conclusion, XOS inclusion can benefit the growth performance and lipid metabolism of common carp fed HFD.
An 8-week feeding trial was performed to investigate effects of dietary selenium (sodium selenite, Na2SeO3; selenium nanoparticle, Nano-Se; selenium yeast, Se-yeast) on the growth, selenium status, antioxidant activities, muscle composition and meat quality of blunt snout bream. Na2SeO3 and Nano-Se were supplemented at 0.2 mg Se kg−1, and Se-yeast was supplemented at 0.1, 0.2, 0.4 and 0.8 mg Se kg−1 in basal diet; no Se was added as a control. The results indicated that groups of 0.2 and 0.4 mg kg−1 Se-yeast had significantly higher weight gain and Nano-Se, 0.2, 0.4 mg kg−1 Se-yeast had significantly lower feed conversation ratio compared with the control group. The Se concentrations of whole body, muscle and liver linearly increased with increasing dietary Se-yeast levels. Group of 0.4 mg kg−1 Se-yeast significantly increased activities of catalase and glutathione peroxidase. Muscle colour of Nano-Se, 0.2, 0.4 mg kg−1 Se-yeast groups, the water-holding capacity of 0.4, 0.8 mg kg−1 Se-yeast groups showed significant differences compared with the control group. The results suggest that Se-yeast and Nano-Se had a better growth performance than Na2SeO3 at 0.2 mg Se kg−1, and supplementing appropriate Se-yeast in diet can increase antioxidant activities and enhance meat quality of blunt snout bream.
A 60-day feeding experiment was conducted to evaluate the effects of fishmeal (FM) replacement with cottonseed meal protein hydrolysate (CPH) on growth, digestion and intestinal histology of juvenile Chinese soft-shelled turtle (Pelodiscus sinensis). Five diets were formulated to replace 0, 50, 100, and 150 g/kg fishmeal protein by CPH (CPH0, CPH5, CPH10, CPH15) and CPH15L (CPH15 with micro capsule-L-lysine). Weight gain, feed conversion rate and protein efficiency ratio showed no significant differences compared to control group (p > .05). The highest feed intake indicated in CPH15 (p < .05). The composition of whole-body varied slightly in each groups (p > .05). The trypsin activity significantly elevated when dietary fishmeal protein was replaced by CPH at 30–90 g/kg (p < .05). A significantly higher lipase activities in CPH5 than control group (p < .05). The CPH5-10 groups showed higher villus height than the other groups (p < .05). The microvillus length in turtles with CPH showed a significant increasing length (p < .05). The results indicated that replacing up to 90 g/kg of dietary fishmeal protein with CPH did not hamper growth or reduce feed intake of turtles. Moreover, CPH replaced 60 g/kg FMP can increase intestine digestive enzymes activities and improve intestinal development.
This study aimed to determine the optimal dietary niacin requirement of juvenile Megalobrama amblycephala. Fish, with an average weight of 3.62 ± 0.02 g, were randomly divided into six groups and fed six purified diets with graded levels of niacin (0, 10, 20, 30, 40 and 50 mg/kg) three times daily for 8 weeks. The survival rate, weight gain (WG), feed conversion ratio, protein efficiency and protein retention all significantly improved (p < .05) as the dietary niacin level increased from 0 to 30 mg/kg but showed no significant difference (p > .05) with further increases in niacin levels. The supplementation of 30 mg/kg niacin also led to a significant (p < .01) reduction in the viscerosomatic index, hepatosomatic index and mesenteric fat index. The dietary niacin levels exhibited minimal effects on whole-body moisture and ash content (p > .05) but exerted a significant (p < .05) influence on protein and lipid contents and liver nicotinamide concentrations with high values obtained in fish receiving greater than 30 mg/kg of niacin. In addition, moderate levels of niacin lowered plasma triglycerides, non-esterified fatty acid and low-density lipoprotein cholesterol concentrations (p < .05). Based on the broken-line regression analysis of WG and liver nicotinamide content, the optimal dietary niacin requirement of juvenile blunt snout bream was 31.25 and 30.62 mg/kg, respectively.
This study was conducted to investigate the effects of fructooligosaccharide (FOS) and Bacillus licheniformis (B. licheniformis) on growth performance, body composition, intestinal enzymes activities and gut histology of Megalobrama terminalis. Nine experimental diets were formulated to contain three FOS levels (0, 3 and 6 g kg−1) and three B. licheniformis levels (0, 1 and 5 × 107 CFU g−1) following a 3 × 3 factorial design. Accordingly, diets were named as 0/0, 0/3, 0/6, 1/0, 1/3, 1/6, 5/0, 5/3 and 5/6 (B. licheniformis/FOS). At the end of the 8-week feeding trial, weight gain (WG) and specific growth rate (SGR) of fish fed 6 g kg−1 FOS were both significantly (P < 0.01 and P < 0.05) higher than that of the other groups in terms of dietary FOS levels. Besides, WG and SGR of fish fed 1 × 107 CFU g−1 B. licheniformis were significantly (P < 0.05) higher than that of the control group in terms of dietary B. licheniformis levels. In addition, a significant interaction (P < 0.05) between dietary FOS and B. licheniformis was observed in finial weight, WG, SGR as well as the survival rate with the highest values all observed in fish fed diet 1/3. Hepatosomatic index, carcass lipid content, lipase activities as well as microvilli length increased significantly (P < 0.05) from 0 to 1 × 107 CFU g−1, but no significant difference (P > 0.05) was observed in terms of dietary FOS levels. In addition, a significant (P < 0.05) interaction of FOS and B. licheniformis was observed in both protease and Na+, K+-ATPase activities with the highest value obtained in fish fed diet 1/3. The results indicated that the dietary applications of dietary FOS and B. licheniformis alone or in combination can significantly improve the growth performance, survival rate, intestinal enzymes activities as well as microvilli length of triangular bream. In addition, there is a significant interaction between dietary FOS and B. licheniformis. The best combination for this species is 3 g kg−1 FOS with 1 × 107 CFU g−1 B. licheniformis.
Five 2-week feeding trials were conducted to investigate five stimulants on P. sinensis. Two isonitrogenous and isoenergetic diets were formulated, one contained 600 g kg–1 fishmeal (FM diet) and the other contained 420 g kg–1 fishmeal and 225 g kg–1 animal protein blend (APB diet), and each tested one stimulant with four levels. The feeding stimulant candidates were betaine, 2-carboxy-ethyl dimethyl sulphonium bromide (DMPT), inosine-5′-monophosphate (IMP), taurine and squid extract. In the experiment on each stimulant, turtles (10.85 ± 0.10 g) were equally divided into FM and APB groups and fed with an equal mixture of corresponding diets containing four levels of stimulants, respectively. Each diet contained a unique rare earth oxide as inert marker. Turtles were fed twice daily (8:00 and 17:00), and faeces were collected. Preference for each diet was estimated based on the relative concentration of each marker in the faeces. In the FM group, only IMP showed the enhanced attraction. But in APB groups, all the stimulants, except IMP, showed higher preference than basal diets for at least one inclusion level, and the optimum level was 10 g kg–1 for betaine, 0.1 g kg–1 for DMPT, 0.1 g kg–1 for IMP, 5 g kg–1 for taurine and 10 g kg–1 for squid extract, and the squid extract had the strongest stimulating effect among the stimulants.
An 8-week feeding trial was conducted to evaluate the potential of partial replacement of fish meal with rendered animal protein blend (APB) [meat and bone meal (MBM): expanding blood meal (EBM) = 4 : 1] in the diet of juvenile Chinese soft-shelled turtle Pelodiscus sinensis. Seven isonitrogenous and isoenergetic practical diets replacing 0%, 10%, 20%, 30%, 40%, 50% and 60% fish meal protein by APB were formulated. Weight gain, feed efficiency, protein efficiency and the apparent digestibility coefficients (ADCs) of dry matter and gross energy in the experimental diets all exhibited no significant difference (P > 0.05) when dietary fish meal was replaced for 0–40%, but decreased significantly (P < 0.05) with further increasing substitution levels. However, relative feed intake, ADC of lipid as well as the contents of whole-body moisture, protein, lipid and ash all showed little differences (P > 0.05) among all the treatments. Nitrogen retention and the ADCs of protein and most amino acids all decreased significantly (P < 0.05) when fish meal was substituted by more than 30%. The results indicated that fish meal in the practical diet of juvenile Chinese soft-shelled turtle could be replaced by 30–40% using a combination of MBM and EBM without negative effects on growth performance, nutrients digestibility and body composition.
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