Effects of dietary supplementation with zinc methionine on gonadal development, growth, and intestinal microbiota in female giant river prawn Macrobrachium rosenbergii

This study investigated the effects of adding different levels of Zinc Methionine（Zn-Met）in feed on growth, gonadal development, and intestinal microbiota of female Macrobrachium rosenbergii . Five isonitrogenous and isolipidic experimental diets were formulated, with supplemented Zn-Met at levels of 0 (CON), 30 (ZM30), 60 (ZM60), 90 (ZM90), and 120 (ZM120) mg/kg, respectively. The actual Zn levels in the diets were 49.82, 80.21, 104.68, 137.97, and 164.01 mg/kg, respectively. Prawns (10.7 ± 0.4 g) were fed for 56 days. The results showed that the ZM60 and ZM120 groups had significantly higher survival rate ( P < 0.05). The weight gain and specific growth rate were significantly higher in the ZM60, ZM90, and ZM120 groups ( P < 0.05). The ZM90 group had significantly higher gonadosomatic index ( P < 0.05), and the proportion of ovarian stage IV reached 58.39%, which was significantly higher than CON group ( P < 0.05). The serum vitellogenin level in the ZM90 group was significantly higher than in the other groups ( P < 0.05). The serum levels of 17β-estradiol in the ZM90 and ZM120 groups were significantly higher than other groups ( P < 0.05), and the progesterone level in the ZM60 group was significantly higher than other groups ( P < 0.05). Gene expression analysis indicated that the ZM90 group significantly upregulated the expression of 17β-HSD , VgR, cyclin B, and cyclin E genes ( P < 0.05). Analysis of Intestinal microbiota revealed that Zn - Met supplementation significantly increased the abundance of Firmicutes and Lactococcus , inhibited Aeromonas . In conclusion, the optimal actual Zn level for female M. rosenbergii ovarian development is 114.62–150.68 mg/kg, which can enhance the growth performance, gonadal development, and microbial diversity of female M. rosenbergii . • Dietary Zn-Met increased gonadosomatic index in giant river prawn. • Dietary Zn-Met elevated serum sex hormones (E2, VTG, PROG). • Zn-Met upregulated gonadal development genes ( E75, 17β-HSD, VgR, cyclinB, cyclin E, AKT). • Zn-Met altered intestinal microbiota composition in giant river prawn. • Optimal dietary Zn: 114.62–150.68 mg/kg for ovarian development in female M. rosenbergii .