SODIUM BUTYRATE ADDITION IN HIGH-LIPID DIET ON GROWTH, DIGESTIVE ENZYMES ACTIVITY, IMMUNITY, AND ANTIOXIDANT CAPACITY OF HETEROPHILIC SILVER CARP (CARASSIUS AURATUS GIBELIO)

In order to investigate the effects of adding sodium butyrate to high-lipid diet on growth, digestive enzymes activity, immunity, and antioxidant capacity of juvenile <italic>Carassius auratus gibelio</italic>, this experiment selected 450 healthy juvenile <italic>C. auratus gibelio</italic> with an initial body weight of (20.41±0.44) g as the research subjects. The high-lipid diet (crude lipid content of 7.31%) with different sodium butyrate supplemental levels [0 (SB0), 0.1% (SB0.1), 0.3% (SB0.3), 0.6% (SB0.6), and 1.2% (SB1.2)] were fed to <italic>C. auratus gibelio</italic> for 8 weeks. The results showed that: (1) In terms of growth, the weight gain rate (WGR) and specific growth rate (SGR) of the SB0.3 and SB0.6 groups were significantly higher than those of the other groups (<italic>P</italic>&lt;0.05), with SB0.3 group showing the highest values (120.63% and 1.41%/d, respectively). The feed conversion ratio (FCR) decreased first and then increased with sodium butyrate addition (<italic>P</italic>&lt;0.05), reaching a minimum of 1.60 at 0.3% supplementation. The addition of sodium butyrate to high-lipid diet significantly increased the protein deposition rate (<italic>P</italic>&lt;0.05); (2) Compared with the control group, intestinal lipase and amylase activities in SB0.1, SB0.3, SB0.6, and SB1.2 groups were significantly increased (<italic>P</italic>&lt;0.05), while protease activity was significantly higher in the SB0.3 group (<italic>P</italic>&lt;0.05), and there was no significant difference between the control group and the other sodium butyrate addition groups (<italic>P</italic>&gt;0.05); (3) In terms of immunity and antioxidant status, serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activities exhibited a trend of first decreasing then increasing with the increase of sodium butyrate supplemental level (<italic>P</italic>&lt;0.05); The hepatopancreas antioxidant enzyme activity increased first and then decreased (<italic>P</italic>&lt;0.05), while malondialdehyde (MDA) content showed the opposite trend (<italic>P</italic>&lt;0.05). This experiment confirms that adding an appropriate amount of sodium butyrate to high-lipid diet can significantly improve the digestive capacity, enhance immunity and antioxidant functions, and promote growth in juvenile <italic>C. auratus gibelio</italic>. Quadratic regression analysis of growth performance combined with the activity of digestive enzymes, immunity and antioxidant capacity, suggests an optimal sodium butyrate dosage range of 0.3%—0.67%.