Dietary baicalein improves growth performance, antioxidant activity, and intestinal flora of koi carp (Cyprinus carpio)

Abstract

Baicalein is a flavonoid that is widely found in plants. Studies have shown that baicalein has growth promoting, antioxidant, antitumor, and antibacterial effects. The objective of this study was to evaluate the effect of baicalein on growth, antioxidant capacity, and intestinal flora of koi carp (Cyprinus carpio). A total of 216 koi weighing 15.34 ± 0.21 g were divided into four treatment groups, with three replicates of 18 fish per group. Baicalein was supplemented to the basal diet at 0 % (control), 0.1 %, 0.3 %, or 0.5 %. Fish were fed at 1–2 % of initial body weight per day for eight weeks. Blood and tissue samples were collected at the end of the trial to determine immune and intestinal bacterial communities. The results showed that dietary supplementation with 0.1 % and 0.3 % baicalein significantly increased the weight gain rate (P < 0.01), specific growth rate (P < 0.01), and liver-to-body ratio (P < 0.01), and the fatness was significantly increased in the 0.3 % group (P < 0.01). The activities of liver catalase (CAT) and superoxide dismutase (SOD) were significantly increased in the 0.3 % and 0.5 % groups (P < 0.01). The activity of liver malondialdehyde (MDA) was significantly decreased, and the activity of liver lysozyme (LZM) was significantly increased in the 0.3 % group (P < 0.01). The activity of renal lysozyme (LZM) was significantly increased in the 0.3 % and 0.5 % groups (P < 0.01), and IL-1α was significantly decreased in the 0.3 % group (P < 0.01). LEfSe analysis showed that at the genus level, Mycobacterium and Streptococcus were enriched in the 0.1 % baicalein-treated group, and Polynucleobacter and Burkholderia-Caballeronia-Paraburkholderia were enriched in the control group. In summary, baicalein significantly improved the growth performance, antioxidant index, immune response, and intestinal flora of koi, and the optimum inclusion rate of baicalein was 0.3 %.