Abstract
Simple SummaryPlant-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.
Highlights
Fish culture is subject to considerable constraints on fish production due to frequent disease occurrence and low survival rates [1]
Traditional aquaculture management approaches can increase the occurrence of antibiotic-resistant strains, destroy or alter the natural microbial community of the environment, and leave residues in fish products [4,5]
These factors have contributed to an urgent demand for aquaculture production free from antibiotics and chemicals, raising interest in the development of plant-derived feed additives as alternatives to traditional chemotherapy and antibiotics for improving fish growth and immunity [6]
Summary
Fish culture is subject to considerable constraints on fish production due to frequent disease occurrence and low survival rates [1]. Fish farmers use synthetic antibiotics or chemotherapy to manage pathogens, reduce stress, improve immunity, and increase fish resistance to disease [2,3]. Traditional aquaculture management approaches can increase the occurrence of antibiotic-resistant strains, destroy or alter the natural microbial community of the environment, and leave residues in fish products [4,5]. These factors have contributed to an urgent demand for aquaculture production free from antibiotics and chemicals, raising interest in the development of plant-derived feed additives as alternatives to traditional chemotherapy and antibiotics for improving fish growth and immunity [6]. High production costs, unavailability, and short-term effectiveness limit the practical application of these immunostimulants [7,8]
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