Combined application of glycerol monolaurate and tributyrin improves the growth performance, antioxidant capacity, nonspecific immunity, gene expression and intestinal health of juvenile Litopenaeus vannamei

This study aimed to investigate the effects of the glycerol monolaurate (GML) and tributyrin (TB) and their interaction on the growth performance, body composition, nonspecific immunity, gene expression and intestinal microbiota of Litopenaeus vannamei (initial weight 0.24 +/- 0.00 g). The feeding trial comprised a completely randomized 3 x 2 factorial design and six formulated diets with two different GML levels (0.10% and 0.15%) and three different TB levels (0.10%, 0.15%, and 0.20%) named G10T10, G10T15, G10T20, G15T10, G15T15, and G15T20, respectively. Results showed that three groups (G10T15, G15T10, and G15T15) had significantly higher final mean weight, weight gain rate, specific growth rate (P < 0.05) and lower feed conversion ratio than the other groups (P < 0.05). Catalase at low and medium addition levels of TB (G10T10, G10T15, G15T10, and G15T15) was promoted by GML (P < 0.05), and malondialdehyde was inhibited by GML (P < 0.05). Glutathione in G10T15 and G15T10 had the highest values among the groups (P < 0.05). Acid phosphatase was greatly influenced by GML, TB, and their interaction, and its maximum value was found in G15T10 (P < 0.05). Alkaline phosphatase was influenced by TB and was significantly higher in G10T15 and G15T15 than in the other groups (P < 0.05). The mRNA expression of lysozyme (LZM), heat shock protein 70 (HSP70), and phenol oxidase (PO) were significantly affected by GML, TB, and their interaction (P < 0.05). At the phylum level, Firmicutes and Firmicutes/Bacteroidetes ratio increased and then decreased at low level of GML (0.10%) and gradually decreased at high level of GML (0.15%), with minimum values in the G10T15 and G15T10 groups (P < 0.05). In conclusion, 0.15% GML and 0.10% TB were the optimal dietary addition on the basis of growth performance, nonspecific immunity, and intestinal health of the juvenile shrimp (Litopenaeus vannamei).