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

To investigate the effects of supplementing the diet with <i>Caulerpa lentillifera</i> on the growth performance, antioxidant capacity, and intestinal microbiota of <i>Litopenaeus vannamei</i>, 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 <i>C. lentillifera</i> 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% <i>C. lentillifera</i> enhanced growth performance and significantly increased the crude protein content in whole shrimp (<i>p</i> < 0.05). Based on the feed conversion ratio (FCR) and protein efficiency ratio (PER) metrics, the optimal inculusion range of <i>C. lentillifera</i> in <i>L. vannamei</i> 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 (<i>p</i> < 0.05). Dietary supplementation with 5-7.5% <i>C. lentillifera</i> 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 (<i>p</i> > 0.05). Analyses of intestinal microbiota sequencing revealed that the addition of 5-7.5% <i>C. lentillifera</i> improved the intestinal microbiota's composition and structural characteristics with a focus on metabolic pathways. In conclusion, the inclusion of dietary <i>C. lentillifera</i> positively influenced growth performance, antioxidant capacity, and the intestinal microbiota of <i>L. vannamei</i>. However, excessively high-dose dietary levels may have adverse effects on shrimp; thus, a dietary inclusion level of 5.25-7.15% <i>C. lentillifera</i> is recommended.