Effects of the addition of Enteromorpha prolifera meal and its derivatives in diets on the growth performance, antioxidant capacity and immune ability of largemouth bass (Micropterus salmoides)

The research investigated the effects of Enteromorpha ( Ulva ) prolifera meal and its derivatives ( E. prolifera hydrolysate, E. prolifera protein, and E. prolifera polysaccharide) in diets on growth performance, liver antioxidant activity and immunity, largemouth bass ( Micropterus salmoides ). Five experimental groups were arranged, with the control group (CTRL, D1), adding the E. prolifera hydrolysate group (EPH, D2), adding the E. prolifera protein group (EPP, D3), adding the E. prolifera polysaccharide group (EPPS, D4), adding the E. prolifera meal group (EPM, D5). Five groups of largemouth bass were fed for 8 weeks. The addition of EPH, EPP and EPPS improved growth performance, final body weight, weight gain rate and specific growth rate of largemouth bass and reduced feed conversion ratio, 17 % increase in WG of EPH group. Meanwhile, the addition of EPH and EPPS could improve the histomorphological health of the liver of largemouth bass, enhance the antioxidant properties of the liver (T-SOD, CAT, GSH), reduce the content of MDA in the liver, and reduce oxidative damage. The inflammation-related genes of the liver showed that the addition of EPH and EPPS could increase the expression level of anti-inflammatory factors and decrease the expression level of pro-inflammatory factors, which indicated that two E. prolifera products could effectively reduce the level of inflammation in largemouth bass, and the apoptosis-related genes in the liver showed that the addition of EPH and EPPS could decrease the expression level of pro-apoptotic genes, and cell apoptosis was reduced. This study suggests that EPH and EPPS can be used as potential functional additives to improve growth performance and liver health in aquatic animals. • EPH and EPPS supplementation significantly improved growth performance in largemouth bass. • EPH and EPPS enhanced liver health by improving tissue morphology, boosting antioxidant capacity, and reducing inflammation. • EPH and EPPS show promise as functional feed additives for aquaculture species.