Dietary Exogenous α-Amylase Modulates the Nutrient Digestibility, Digestive Enzyme Activity, Growth-Related Gene Expression, and Diet Degradation Rate of Olive Flounder ( Paralichthys olivaceus )

• Published in: Journal of microbiology and biotechnology 2023-10, Vol.33 (10), p.1390-1401
• Main Authors: Hasan, Md. Tawheed, Kim, Hyeon Jong, Hur, Sang-Woo, Jeong, Seong-Mok, Kim, Kang-Woong, Lee, Seunghan
• Format: Article
• Language: English
• Subjects: Research article
• ISSN: 1017-7825; 1738-8872
• DOI: 10.4014/jmb.2303.03033

In this study, a 12-week feeding experiment was conducted to characterize the effects of exogenous α-amylase on the growth, feed utilization, digestibility, plasma α-amylase activity, feed degradation rate, and fecal particle size of olive flounder ( Paralichthys olivaceus ). Diet was supplemented with 0 (AA 0 ; control), 100 (AA 100 ), 200 (AA 200 ), or 400 (AA 400 ) mg/kg of α-amylase, respectively. Fish (273.1 ± 2.3 g) were stocked into 12 tanks (25 fish/1,000-L tank) and 3 tanks were randomly selected for each diet group. As a result, α-amylase was found to have no significant effects ( p ≥ 0.05) on the growth, feed utilization parameters, and whole-body proximate compositions. α-Amylase-treated fish exhibited only a significant increase in the apparent digestibility coefficient of carbohydrates compared to the controls. In addition, in vitro analyses revealed that α-amylase dose-dependently increased ( p < 0.05) the feed degradation rate, while photographs of the intestinal content after 2, 4, and 8 h of feeding demonstrated an improved degradation rate in the α-amylase-treated groups. Plasma α-amylase content was higher in the AA 200 and AA 400 groups, whereas the control group produced significantly larger-sized fecal particles (90% size class) than these two groups. In the intestine, no changes were observed in the expression levels of the immune-related TNF-α, IL-1β, IL-2, immunoglobulin-M, HSP-70, lysozyme, and amylase alpha-2A. However, growth-related genes IGF-1, IGF-2, TGF-β3, and growth hormone genes were upregulated in muscle tissues. Collectively, exogenous α-amylase has positive roles in the modulation of the digestibility coefficient, blood α-amylase concentration, growth-related gene expression, and diet degradation for improved digestion in olive flounder.