Effects of taurine supplementation in low fishmeal diet on growth, immunity and intestinal health of Litopenaeus vannamei

This experiment investigated the impact of taurine supplementation in low fishmeal diets on growth, antioxidant capacity, immunity and intestinal health of Litopenaeus vannamei. In this experiment, five diets were formulated, of which the high fishmeal diet contained 25% fishmeal (HF) and the remaining four diets were a mixture of soybean protein concentrate and Clostridium autoethanogenum protein (CAP) replacing 15% fishmeal and supplemented with 0%, 0.2%, 0.4% and 0.6% taurine (LF, T1, T2, T3). A total of 800 healthy shrimp (0.32 ± 0.00 g) were randomly allocated into 5 groups, with each group consisting of 4 replicates and 40 shrimp per replicate. The shrimp were fed four times a day for 51 days. The results showed that there was no significant difference in weight gain rate and survival (P>0.05). Dietary taurine supplementation significantly improved the antioxidant capacity of shrimp. Compared with LF group, the mRNA expression of alf (anti-lipopolysaccharide factor) and cru (crustins) in HF group were significantly up-regulated (P<0.05). Compared with the HF and LF groups, the mRNA expression of pen3 (penaeidins 3) in T1, T2 and T3 groups was significantly up-regulated, and the mRNA expression of dorsal in T2 group was significantly up-regulated (P<0.05). The mRNA expression of bcl-2 (B-cell lymphoma-2) in T2 group was significantly up-regulated than that in other groups (P<0.05). The mRNA expression of cyt-c (cytochrome c) in LF group was significantly up-regulated than that in other groups (P<0.05). Compared with LF group, the mRNA expression of tnf-a (tumor necrosis factor-alpha) in HF, T2 and T3 groups was significantly down-regulated (P<0.05). The mRNA expression of caspase8 in HF and T2 group was significantly down-regulated than that in other groups (P<0.05). Compared with LF group, the mRNA expression of caspase3 in T1 groups was significantly down-regulated (P<0.05). Intestinal H&E stained sections showed that dietary taurine supplementation improved intestinal mucosal folds height, width and muscle layer thickness. In general, dietary taurine supplementation can improve the antioxidant capacity, immunity and intestinal health of Litopenaeus vannamei, and the optimal supplemental level is 0.4%.