Effects of Dietary Zinc on Growth Performance, Digestive Enzyme Activities, Antioxidant Status, and Immune Responses of Sea Cucumber Apostichopus japonicus

Abstract

This study evaluated the effects of dietary zinc on growth performance, digestive enzyme activities, antioxidant status and immune responses of sea cucumber Apostichopus japonicus. Five experimental diets were formulated with graded levels of zinc (0, 20, 40, 60, and 80 mg/kg, respectively), and the actual dietary zinc values were 31.4, 51.0, 68.2, 91.9, and 110.8 mg/kg diet, respectively. Sea cucumbers were fed with diets for 2 months. The results showed the growth performance, amylase and trypsin activities of sea cucumber increased signi cantly with zinc supplementation, and the best growth performance and enzyme activities were observed at 40 mg/kg zinc diet. Zinc supplementation signi cantly increased activities of superoxide dismutase (SOD), catalase (CAT), anti-superoxide anion (ASA) and inhibiting hydroxyl radical (AHR), while signi cantly reduced the malondialdehyde (MAD) content. Furthermore, the higher Zn supplementation levels resulted in signi cantly upregulated immune-related genes of hsp90 p105 rel lsz, suggesting that excessive zinc caused oxidative stress. The broken-line regression analysis of speci c growth rate (SGR) indicated dietary zinc requirement in sea cucumber was ~ 66.3 mg/kg diet.