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Niacin is indispensable for the growth and development of aquatic animals. However, the correlations between dietary niacin supplementations and the intermediary metabolism of crustaceans are still poorly elucidated. This study explored the effects of different dietary niacin levels on the growth, feed utilization, energy sensing, and glycolipid metabolism of oriental river prawn Macrobrachium nipponense. Prawns were fed with different experimental diets containing graded niacin levels (15.75, 37.62, 56.62, 97.78, 176.32, and 339.28 mg/kg, respectively) for 8 weeks. Weight gain, protein efficiency, feed intake, and hepatopancreas niacin contents all maximized in the 176.32 mg/kg group with significance noted with the control group ( P < 0.05 ), whereas the opposite was true for feed conversion ratio. Hepatopancreas niacin concentrations increased significantly ( P < 0.05 ) as dietary niacin levels increased, and peaked at the 339.28 mg/kg group. Hemolymph glucose, total cholesterol, and triglyceride concentrations all maximized in the 37.62 mg/kg group, while total protein concentration reached the highest value in the 176.32 mg/kg group. The hepatopancreas mRNA expression of AMP-activated protein kinase α and sirtuin 1 peaked at the 97.78 and 56.62 mg/kg group, respectively, and then both decreased as dietary niacin levels increased furtherly ( P < 0.05 ). Hepatopancreas transcriptions of the genes related to glucose transportation, glycolysis, glycogenesis, and lipogenesis all increased with increasing niacin levels up to 176.32 mg/kg, but decreased significantly ( P < 0.05 ) as dietary niacin levels increased furtherly. However, the transcriptions of the genes related to gluconeogenesis and fatty acid β-oxidation all decreased significantly ( P < 0.05 ) as dietary niacin levels increased. Collectively, the optimum dietary niacin demand of oriental river prawn is 168.01-169.08 mg/kg. In addition, appropriate doses of niacin promoted the energy-sensing capability and glycolipid metabolism of this species.

Six diets were designed to investigate the effects of dietary docosahexaenoic acid (22:6n‐3; DHA) levels (0.5, 1.3, 2.3, 4.2, 8.1 and 15.9 g/kg diets) on growth performance, fatty acid profile and expression of some lipogenesis‐related genes of blunt snout bream (Megalobrama amblycephala). Fish (average weight: 26.40 ± 0.11 g) were randomly fed one of six diets for 8 weeks. Results indicated that the final body weight (FBW) and specific growth rate (SGR) of fish fed 1.3 g/kg DHA were significantly higher than other groups except for the 2.3 g/kg DHA (p

An 8-week feeding trial was conducted to evaluate the effects of fish meal (FM) replacement by rice protein concentrate (RPC) with supplementation of microcapsule lysine (ML) or crystalline lysine (CL) on growth performance, muscle development and flesh quality of blunt snout bream. Four isonitrogenous and isoenergetic diets were formulated, including FM diet (containing 50 g/kg FM), RPC diet (FM replaced by RPC), MRPC diet (FM replaced by RPC with ML supplementation) and CRPC diet (FM replaced by RPC with CL supplementation). Fish fed FM diet had significantly higher weight gain, feed efficiency, protein efficiency ratio and nitrogen and energy utilization than that of RPC group, but showed no statistical difference with other treatments. In addition, fish fed RPC diet showed higher muscle fibre frequency in the 20- to 50-μm class but lower >50-μm class and higher cooking loss than that of the other groups. Furthermore, no significant difference was found in whole-body proximate compositions, frequency distribution of

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.

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) with further increases in niacin levels. The supplementation of 30 mg/kg niacin also led to a significant (p .05) but exerted a significant (p

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) among all the treatments. Nitrogen retention and the ADCs of protein and most amino acids all decreased significantly (P

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 0.05) was observed in terms of dietary FOS levels. In addition, a significant (P

This study aimed to investigate the optimum dietary carbohydrate/lipid (CHO/L) ratio for fingerling blunt snout bream Megalobrama amblycephala (average initial weight: 6.61 ± 0.03 g). Six isonitrogenous and isoenergetic diets were formulated to contain various CHO/L ratios ranging from 1.62 to 24.20. Each diet was tested in four replicates for 10 weeks. Specific growth rate (SGR), feed conversion ratio and nitrogen and energy retention all improved significantly (P 0.05) as dietary CHO/L ratios ranged from 2.45 to 5.64. Hepatosomatic index increased significantly (P 0.05) among all the treatments, while liver glycogen content increased significantly (P