Growth performance, lipid metabolism, and health status of grass carp ( Ctenopharyngodon idella ) fed three different forms of sodium butyrate

Sodium butyrate (SB) can be coated with fatty acid matrix. In this study, the effects of three SB forms, being zero-lipid-coated (SB-A), half-lipid-coated (SB-B), and 2/3 lipid-coated (SB-C) (w/w), on growth, lipid metabolism, and health status of grass carp (Ctenopharyngodon idella) were investigated. The three forms of SB were added to a control diet to form three SB diets, Con., SB-A, SB-B, and SB-C, where the pure SB in each SB diet was kept at the same level (500 mg kg−1). A total of 216 C. idella (14.10 ± 0.60 g/fish) were allotted into four groups (triplicate per group) and fed the four diets respectively for 56 days, and then fish were sampled and determined. Fish growth was not affected by any of the three forms of SB. Viscerosomatic index, intraperitoneal fat index, and crude lipid of hepatopancreas and muscle were significantly decreased and villus height of intestine and mRNA expression of MyD88 and TLR22 in hepatopancreas were significantly improved in SB diets compared with control (p < 0.05), respectively. MiSeq sequencing of the V3–V4 region of bacterial 16S rRNA gene revealed that SB increased the relative abundances of intestinal healthy bacteria, Fusobacteria and Bacteroides, and the abundances of Cetobacterium decreased in the SB-C group. In conclusion, the present results showed that three forms of SB, without affecting the growth of fish, respectively decreased lipid accumulation and probably have a beneficial effect on health of C. idella.