Effects of Caulerpa lentillifera on Growth Performance, Antioxidant Capacity and Intestinal Microbiota of Litopenaeus vannamei.

To investigate the effects of supplementing the diet with Caulerpa lentillifera on the growth performance, antioxidant capacity, and intestinal microbiota of Litopenaeus vannamei, a total number of 600 healthy shrimp, each having an average body weight of 2.45 ± 0.12 g, were allocated randomly into five experimental groups. These groups comprised a control group receiving a basal diet (Ctrl) and four treatment groups receiving the basal diet supplemented with varying concentrations of dried C. lentillifera powder: 2.5% (CL1), 5% (CL2), 7.5% (CL3), and 10% (CL4). Each group consisted of four replicates, with 30 shrimp per replicate. The experimental duration was 56 days. The findings demonstrated that supplementing the diet with 5-7.5% C. lentillifera enhanced growth performance and significantly increased the crude protein content in whole shrimp (p < 0.05). Based on the feed conversion ratio (FCR) and protein efficiency ratio (PER) metrics, the optimal inculusion range of C. lentillifera in L. vannamei feed was determined to be 5.25-7.15%. Simultaneously, there was a significant increase in the activities of total superoxide dismutase (T-SOD), glutathione peroxidase (GPx), and peroxidase (POD) enzymes in the hepatopancreas, accompanied by a substantial reduction in malondialdehyde (MDA) levels (p < 0.05). Dietary supplementation with 5-7.5% C. lentillifera induced a numerical elevation of the relative expression levels of antioxidant and protein synthesis genes, although no statistically significant differences were detected among all groups (p > 0.05). Analyses of intestinal microbiota sequencing revealed that the addition of 5-7.5% C. lentillifera improved the intestinal microbiota's composition and structural characteristics with a focus on metabolic pathways. In conclusion, the inclusion of dietary C. lentillifera positively influenced growth performance, antioxidant capacity, and the intestinal microbiota of L. vannamei. However, excessively high-dose dietary levels may have adverse effects on shrimp; thus, a dietary inclusion level of 5.25-7.15% C. lentillifera is recommended.