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Simple Summary: Garlic juice is one of the most popular health drinks in Asia. Garlic juice processing waste (GJPW) is a potential feed ingredient for aquaculture, because it is rich in bioactive chemicals, which makes it an attractive alternative to synthetic antibiotics and/or antioxidants. This study investigates the effects of various dietary levels of garlic juice processing waste on the growth performance and health status of juvenile black (Sebastes schlegelii). On the basis of the results, rockfish fed diets supplemented with GJPW show improvement in growth performance, digestive enzyme activity, and growth and antioxidant-related gene expression. Therefore, considering the effects on the overall performance of juvenile rockfish, GJPW is a promising useful additive, and 2.5 g kg−1 dietary GJPW was found to be a suitable dietary level for juvenile rockfish black rockfish. An 8-week feeding trial was conducted to evaluate the effects of various dietary levels of garlic juice processing waste (GJPW) on the growth, feed utilization, digestive and antioxidant enzyme activity, growth- and antioxidant-related gene expression, and resistance to Streptococcus iniae infection of juvenile black rockfish (Sebastes schlegelii). A total of 450 juvenile rockfish were randomly distributed into 30 L rectangular tanks (30 fish per tank). Five experimental diets were prepared in triplicate. The fish were fed experimental diets supplemented with GJPW at concentrations of 0 (GJPW0, control), 2.5 (GJPW2.5), 5 (GJPW5), 7.5 (GJPW7.5), and 10 g kg−1 (GJPW10) diet. All of the GJPW-supplemented treatments (2.5, 5, 7.5, and 10 g kg−1) significantly enhanced weight gain (WG), specific growth rate (SGR), feed efficiency (FE), protein efficiency ratio (PER), and digestive enzyme activity (amylase, trypsin, and lipase). A decreasing trend was seen in plasma aspartate aminotransferase (ALT), alanine aminotransferase (AST), and glucose (GLU) content with increasing dietary levels of GJPW. In contrast, plasma lysozyme and antioxidant enzyme activities were significantly increased with increasing dietary GJPW levels. Furthermore, GJPW administration significantly upregulated the expression of insulin-like growth factor-1 (IGF-1), superoxide dismutase (SOD), catalase (CAT), and glutathione S-transferase (GST) in the liver of rockfish. A challenge test with S. iniae showed significantly higher resistance in the GJPW-supplemented treatments than in the control. In short, dietary supplementation GJPW enhanced growth performance and antioxidant response in juvenile black rockfish, with suitable effects in fish fed with 2.5 g kg−1 GJPW for 8 weeks. [ABSTRACT FROM AUTHOR]

Simple Summary: Plant-derived feed additives are gaining interest as environmentally friendly and practical alternatives to antibiotics in fish aquaculture. In this study, we evaluated the efficacy of a ginger by-product generated from juice extraction as a feed additive for fish. We compared the effects of varying dietary levels of ginger residue from juice extraction (GRJE) on the growth performance and health status of black rockfish. GRJE diet supplementation had a positive influence on growth, feed utilization, non-specific immunity, and disease resistance and produced no adverse effects. Dietary supplementation of 0.75% GRJE is recommended for improving juvenile black rockfish performance. Plant-derived feed additives provide cost effective and environmentally friendly alternatives to antibiotics for improving fish performance in aquaculture. An 8-week feeding trial was conducted to evaluate the effects of dietary ginger residue from juice extraction (GRJE) on juvenile black rockfish (Sebastes schlegelii) growth performance, antioxidant enzyme activities, and resistance to Streptococcus iniae infection. Juvenile rockfish (n = 450; initial weight = 2.2 ± 0.01 g) were randomly distributed into 30 L rectangular tanks (30 fish per tank). Five experimental diets with GRJE concentrations of 0% (control), 0.25%, 0.5%, 0.75% and 1% were prepared in triplicate. Three groups of fish were randomly assigned to each diet and fed to apparent satiation twice daily. After the feeding trial, fish were challenged with S. iniae, and cumulative survival was observed for six days. Growth parameters, feed efficiency, and the protein efficiency ratio showed a quadratic correlation with the GRJE concentration in the fish diet. Proximate composition and plasma chemistry were not significantly affected. Plasma lysozyme, superoxide dismutase, glutathione, and catalase activities linearly increased with increasing GRJE supplementation levels. Moreover, survival in the S. iniae challenge test was significantly higher in fish fed diets supplemented with 0.75–1% GRJE. Our findings demonstrated that 0.75% GRJE dietary supplementation enhanced the growth performance, antioxidant activity, and disease resistance of juvenile black rockfish with no adverse effects. [ABSTRACT FROM AUTHOR]