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A long‐term feeding trials were conducted to evaluate the effect substituting dietary fishmeal with a mixture of plant and animal protein sources on growth, body composition and economic efficiency of young Korean rockfish (Sebastes schlegeli). A fishmeal‐based diet was designated the control (Con). Three among the other six diets, respectively, had 30%, 40% and 50% of its fishmeal replaced by a mixture of plant and animal protein sources (designated as FS30, FS40 and FS50 respectively), while the remaining three diets were FS30, FS40 and FS50 diets supplemented with L‐lysine and L‐methionine (FS30AA, FS40AA and FS50AA respectively). Three replicated groups of fish (initial body weight, 86 ± 1.9 g) were fed one of the seven diets for 30 weeks. By the end of the feeding trials, the survival rate of all experimental groups was over 92%. The final mean weight, weight gain, feed efficiency, protein efficiency ratio and condition factor of fish were not significantly affected by dietary treatments. Incidence cost of FS50 diet was significantly lower than Con diet. FS50 and FS40AA diets exhibited significantly higher profit index than the Con diet. FS40AA and FS50 diets were the best economically, followed by FS40, FS50AA, FS30, FS30AA and Con diets. These results suggest that the dietary fishmeal could be substituted with a mixture of plant and animal protein up to 50% in the diet without a reduction in growth and feed utilization of young Korean rockfish. Taking account of economic efficiency, the FS50 diet is recommendable for young Korean rockfish farming. [ABSTRACT FROM AUTHOR]

Abstract: β‐Glucooligosaccharides (BGO), produced from barley β‐glucan, were used as a feed supplement (0.1%) for juvenile olive flounder (Paralichthys olivaceus) to identify and quantify its oral administration effects on innate immunomodulation and infectious disease protection. Juvenile flounders (14 ± 0.5 g) were divided into two groups fed either 0.1% BGO (treatment) or a standard diet (control) for 8 weeks. At the end of the experiment, investigation of the effects was carried out through systemic studies on growth performance, serum and mucus biochemical parameters, innate immunity, microvillus length, and relative pro‐inflammatory cytokine gene expression. The results demonstrated that the BGO diet produced slightly higher levels of growth performance, serum protein, microvillus length and pro‐inflammatory cytokine gene (tumour necrosis factor‐α, interleukin [IL]‐1β, and IL‐6) expression without any significant differences (p > .05). All innate immunity parameters were up‐regulated by BGO administration and, among these, respiratory burst, lysozyme and superoxide dismutase (SOD) were significantly different (p < .05). Fish in the both groups were challenged with Streptococcus iniae (1.35 × 108 CFU/ml), and BGO group was focused to confirm the promotion of innate immunity parameters. The results showed a significantly (p < .05) lower death rate compared with that of the control. Therefore, BGO could be used as a new prebiotic in future olive flounder aquaculture as well as to control streptococcosis. [ABSTRACT FROM AUTHOR]

This study was conducted to investigate the effects of different taurine levels on the conjugated bile acid composition and growth of juvenile rockfish. Five taurine level diets were made by the supplementation of taurine (0%, 0.5%, 1.0%, 1.5% and 2.0%) to a basal diet. Fish meal washed with 70% ethanol to exclude taurine was used for the sole protein source. Feeding experiments were accomplished at 15°C using juvenile fish (initial BW: 13.5 g). Fish were fed the experimental diets for 4 months. At the end of experiments, fish were weighed and stored at −80°C for analysis of free amino acids and conjugated bile acids contents. The growth performance and feed efficiency of Korean rockfish were improved by taurine supplementation in the experimental diets. The taurine contents of the whole body increased with the increase in the taurine supplementation. The primary conjugated bile acids in gall bladder were taurocholic acid (83.5-165.6 mg mL−1) and taurochenodeoxycholic acid (6.3-20.0 mg mL−1). Total bile acids increased with increases in dietary taurine. Taurocholic acid content was more than 95% of the total conjugated bile acids. This indicates that taurine is the sole amino acid to make conjugated bile acid in Korean rockfish. Dietary taurine levels improved the conjugated bile acid composition in juvenile Korean rockfish. [ABSTRACT FROM AUTHOR]