Effect of astaxanthin dietary supplementation on the crowding stress response and performance of Indian mackerel (Rastrelliger kanagurta)

This experiment was conducted to evaluate the effect of different levels of dietary astaxanthin on the productive performance and stress resistance of Indian mackerel (Rastrelliger kanagurta). The experiment was conducted in a completely randomized design with 120 of Indian mackerel (with average weight of 7.14±0.01g) in 4 treatments and 3 replicates (n=10 in each replicate) and included: control group without using astaxanthin and another groups (treatment 2, 3 and 4) the amounts of this supplement were 50,100 and 150 mg/kg food. After 60 days of feeding, each treatment was exposed to acute crowding stress for 24 h. The results showed that compared with the control treatments containing astaxanthin showed significantly increase in serum total protein (TP), lysozyme activity and significantly decrease in alkaline phosphatase (ALP) activity, alanine aminotransferase (ALT) activity and aspartate aminotransferase (AST) activity (except to treatment 4) at 24 h after the initiation crowding stress (P