Effects of dietary ESTAQUA® yeast culture supplementation on growth, immunity, intestinal microbiota and disease-resistance against Vibrio harveyi in hybrid grouper (♀Epinephelus fuscoguttatus×♂E. lanceolatus)

This study investigated the effects of dietary supplementation of ESTAQUA® yeast culture (YC) on the growth, immunity, intestinal microbiota, and disease-resistance against Vibrio harveyi in hybrid grouper (♀Epinephelus fuscoguttatus×♂E. lanceolatus) at 0% (C0), 2% (N1), and 4% (N2). After 8 weeks of the feeding trial, the results indicated that the survival rate (SR), weight gain rate (WGR), and specific growth rate (SGR) of hybrid grouper were significantly higher in the N1 (2%) and N2 (4%) group than those in the control group (P < 0.05). Serum superoxide dismutase (SOD), catalase (CAT), total protein (TP), alkaline phosphatase (AKP), acid phosphatase (ACP), and immunoglobulin (IgM) activities were significantly higher in the N2 (4%) group (P < 0.05). Contrary to the control, aspartate aminotransferase (AST), alanine aminotransferase (ALT), malondialdehyde (MDA), and glucose (GLU) were notably decreased in the N2 (4%) group (P < 0.05). The activity of intestinal digestive enzymes was significantly higher in the experimental groups than that in the control group (P < 0.05). Furthermore, at the phylum level, the relative abundance of Actinobacteria and Bacteroidetes was remarkably higher in the N2 (4%) group than that in the control group (P < 0.05). The relative abundance of Blautia and Lactobacillus was notably higher in the N2 (4%) group at the genus level (P < 0.05). Hybrid grouper in the N1 (2%) and N2 (4%) groups effectively improved intestinal villus height and width (P < 0.05). Lastly, the protection against V. harveyi challenge in hybrid grouper was enhanced in the YC treatment group, while N2 (4%) experienced the highest cumulative SR of 80%. In conclusion, the N2 (4%) treatment group is suggested as the best to improve the growth and immunity of hybrid grouper.