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Abstract: An 8‐week feeding trial was conducted to evaluate the optimum dietary protein‐to‐energy (P/E) ratio in juvenile whiteleg shrimp, Litopenaeus vannamei. Six diets were formulated with two protein levels (30% and 35%) and three digestible energy levels (16, 17.5 and 19 kJ/g diet) at each protein level (30P16, 30P17.5, 30P19, 35P16, 35P17.5 and 35P19). Fifty shrimp averaging 0.97 ± 0.03g (Mean ± SD) were randomly distributed in biofloc tanks and fed one of the experimental diets. Weight gain (WG), specific growth rate (SGR) and feed efficiency (FE) of shrimp fed the 35P17.5 diet were significantly higher than those of shrimp fed 30P16, 30P17.5 and 30P19 diets (p < .05). Results for non‐specific immune responses showed that diet 35P17.5 caused higher lysozyme activity in shrimp comparing to lower protein diets. Thiobarbituric acid reactive substances (TBARS) of plasma were lower for shrimp fed on diets consisting of higher protein and energy levels than shrimp fed on the 30P19 diet. Analyses of digestive enzyme activities showed higher trypsin activities for shrimp fed on 35P17.5 and 35P19 diets comparing to 30P16 and 30P17.5 diets. Also, hepatopancreatic lipase activity of shrimp fed 35P16, 35P17.5 and 35P19 diets were significantly higher than those of shrimp fed the other diets. In conclusion, based on the results for growth performance, biochemical parameters, immune responses, oxidative stress and enzyme activities, 35% protein and 17.5 kJ/g digestible energy (35P17.5) could be considered as the optimum protein‐to‐energy ratio in the diet of juvenile whiteleg shrimp reared in a biofloc system. [ABSTRACT FROM AUTHOR]

A 12-wk feeding trial was conducted to evaluate the effects of the dietary fishmeal analogue ( FMA) adding 2% shrimp soluble extract ( SSE) on growing rainbow trout, Oncorhynchus mykiss. Fish averaging 146 ± 3.8 g (mean ± SD) were randomly distributed into 500-L aquaria as groups of 20 fish per tank. Fish were fed the experimental diets in triplicate groups to apparent satiation twice a day on a dry matter basis. Each group was fed one of the four experimental diets: control (FM100% + FMA0%), FMA0 (FM100% + FMA0% + SSE2%), FMA12 (FM88% + FMA12% + SSE2%), and FMA24 (FM76% + FMA24% + SSE2%). After the feeding trial, weight gain and specific growth rate of fish fed the FMA0 and FMA12 diets were significantly higher than those of fish fed the FMA24 diet ( P < 0.05). Feed efficiency and protein efficiency ratio values of fish fed the control, FMA0, and FMA12 diets were significantly higher than those of fish fed the FMA24 diet ( P < 0.05). The values of superoxide dismutase activity showed significantly higher amounts for the FMA0, FMA12, and FMA24 groups than the control group ( P < 0.05). Lysozyme activity in the FMA12 group was significantly higher than in the control group ( P < 0.05). Therefore, according to our results, FMA with additive SSE can be used up to 12% as a substitute of fishmeal for growing rainbow trout. [ABSTRACT FROM AUTHOR]

A feeding trial was conducted to determine the optimum level and effect of incremental dietary levels of docosahexaenoic acid ( DHA, 22:6n-3) on growth and non-specific immune responses in juvenile rock bream, Oplegnathus fasciatus. A basal diet without DHA supplementation was used as a control, and six other diets were prepared by supplementing with 4, 8, 12, 16, 20 or 40 g kg−1 DHA. These diets included no eicosapentaenoic acid and/or arachidonic acid contents. The actual DHA concentrations of the diets were 1, 4.8, 8.9, 13.1, 17.6, 21.2 and 41.4 g kg−1 diet ( DHA1.0, DHA4.8, DHA8.9, DHA13.1, DHA17.6, DHA21.2 and DHA41.4 respectively). At the end of feeding trial, final body weight, weight gain, specific growth rate and feed efficiency of fish fed the DHA13.1, DHA17.6, DHA21.2 and DHA41.4 diets were significantly higher than those fed the other diets ( P < 0.05). The broken-line analysis of weight gain indicates that the optimum dietary DHA level is 11.9 g kg−1. Fish fed DHA1.0 had the highest hepatosomatic index, an increase in plasma cholesterol, triglyceride, low-density lipoprotein and aspartate aminotransferase levels, as well as a decrease in high-density lipoprotein. Superoxide dismutase activity of fish fed DHA13.1 and DHA17.6 diets was significantly higher than that of fish fed DHA1.0, DHA4.8 and DHA8.9 diets. Fish fed the DHA17.6, DHA21.2 and DHA41.4 diets showed significantly higher lysozyme activity than those fish fed DHA1.0, DHA4.8 and DHA8.9 diets. Therefore, the optimum dietary DHA level could be greater than 11.9 g kg−1 but less than 13.1 g kg−1 in diet. [ABSTRACT FROM AUTHOR]

An 8-week feeding trial was conducted to evaluate the effects of dietary probiotics on growth, non-specific immune responses and disease resistance in juvenile rainbow trout, Oncorhynchus mykiss. Fish averaging 5.8 ± 0.8 g (mean ± SD) were fed one of the five experimental diets; one control (Cont), and four other diets were prepared by supplementing single probiotics 1 ( Bacillus subtilis; SP1, 0.5%), single probiotics 2 ( Bacillus licheniformis; SP2, 0.5%), multi-probiotics ( B. subtilis + B. licheniformis; MP, 0.5%) and oxytetracycline ( OTC) at 5 g OTC kg−1 diet. After 8 weeks of the feeding trial, weight gain and specific growth rate of fish fed SP1, SP2 and OTC diets were significantly higher than those of fish fed Cont diet ( P < 0.05). Superoxide dismutase ( SOD) and lysozyme activities of fish fed SP1, SP2 and MP diets were significantly higher than those of fish fed Cont diet ( P < 0.05). There were no significant differences in SOD and lysozyme activities among fish fed SP1, SP2, MP and OTC diets. In challenge test with Aeromonas salmonicida for 15 days, fish fed SP1, SP2 and MP diets showed significantly higher cumulative survival rate than those of fish fed Cont diet ( P < 0.05). However, there were no significant differences in cumulative survival rate among fish fed SP1, SP2, MP and OTC diets. Although there was a little advantage in fish fed MP diet in terms of non-specific immune responses, single or multi-probiotics are equally effective statistically. These results indicate that single or multi-probiotics had equal beneficial effects as an antibiotic replacer on growth performance, non-specific immune responses and disease resistance in juvenile rainbow trout. [ABSTRACT FROM AUTHOR]

Abstract This study evaluated the synergistic effects of dietary Bacillus subtilis WB60 and mannanoligosaccharide (MOS) in juvenile Japanese eel, Anguilla japonica. Seven treatment diets were formulated to contain three different levels of B. subtilis (0.0, 0.5, and 1.0 × 107 CFU/g diet denoted as BS 0 , BS 0.5 , and BS 1 , respectively) with two MOS levels (0 and 5 g/kg diet denoted as M 0 and M 5 , respectively), and one diet with oxytetracycline (OTC) at 5 g/kg diet. Each diet (BS 0 M 0 (CON), BS 0 M 5 , BS 0.5 M 0, BS 0.5 M 5, BS 1 M 0, BS 1 M 5 , and OTC) was fed to triplicate groups of 20 fish averaging 9.00 ± 0.11 g (mean ± SD) for eight weeks. Average weight gain, feed efficiency, specific growth rate and protein efficiency ratio of fish fed the BS 0.5 M 5 and BS 1 M 5 diets were significantly higher than those of fish fed CON, BS 0.5 M 0 and OTC diets (P < 0.05). Significant increases in the nonspecific enzymatic activities (e.g., lysozyme and myeloperoxidase) were detected from fish fed the BS 0.5 M 5 , BS 1 M 5 , and OTC diets compared to the CON, BS 0.5 M 0 , and BS 0 M 5 diets (P < 0.05). Whereas, immunoglobulin M expressions were recorded significantly higher for fish fed the BS 0.5 M 5 and BS 1 M 5 diets compared to those of fish fed the other diets (P < 0.05). Also, heat shock protein 70 mRNA levels of fish fed BS 0.5 M 5 and BS 1 M 5 diets were significantly higher than those of fish fed the CON diet (P < 0.05). Histological observations of the intestinal morphology showed healthier gut for fish fed BS 0.5 M 5 and BS 1 M 5 diets than those fed CON, BS 0 M 5 , and OTC diets. Additionally, resistance to bacterial challenge with Vibrio anguillarum was recorded significantly lower for fish fed the CON diet than those fed other diets (P > 0.05). Therefore, the results for growth performance, non-specific immune responses, intestinal morphology, and disease resistance demonstrated that supplementation of B. subtilis at 0.5 × 107 CFU/g diet and mannanoligosaccharide at 5 g/kg diet could have beneficial synergistic effects in Japanese eel. The isolated probiotic from eel and the selected prebiotic could lead to the development of a specific and potential synbiotic in Japanese eel aquaculture. Highlights •Higher growth and immunity could be achieved by the administration of Busilus subitlis and mannanoligosaccharide. •Dietary synbiotic could have more benefits than probiotic and prebiotic alone. •Specific synbiotic has the potential to replace chemical antibiotics in Japanese eel aquaculture. [ABSTRACT FROM AUTHOR]