Tian-Dong-Tang-Gan powder (TDTGP) is a newly developed immune enhancer in Litopenaeus vannamei. In vitro, TDTGP was non-toxic to haemolymph at 400 µg ml −1 and increased the activities of phenol oxidase (PO), acid phosphatase (ACP) and superoxide dismutase (SOD) after incubation with haemolymph for 8-48 h. In vivo, the activities of PO, SOD, ACP and alkaline phosphatase (AKP) in the shrimp haemolymph could be increased during the 28-day feeding trials. An acute ammonia stress test was performed

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... after the feeding trials were terminated. We studied the immunological parameters and histology diagnosis. In the drug group, the immune index burst following acute ammonia exposure was higher than that in the negative control and control groups. Histological detection showed that the integrity of the hepatopancreas cells in the TDTGP groups was higher than that in the negative control group at 72 h after ammonia exposure. The results showed that feeding shrimp TDTGP for 28 days could improve the immunity and resistance to ammonia stress by Litopenaeus vannamei and protect the integrity of the hepatopancreas during ammonia stress. These findings showed that TDTGP can be developed and used as an immunoenhancer in Litopenaeus vannamei. K E Y W O R D S acute ammonia stress, immunoenhancer, Litopenaeus vannamei, Tian-Dong-Tang-Gan powder | 3361 XIE Et al.