Short-term effects of diets containing a water-soluble extract of Angelica sinensis on growth performance and hypoxia tolerance of juvenile Jian carp (Cyprinus carpio var. Jian)

Abstract

This study investigated the short-term effects of water-soluble extract of Angelica sinensis (WEAs) on fish growth performance and hypoxia tolerance. All 420 carp (Cyprinus carpio var. Jian; 6.64 ± 0.02 g) were fed 7 diets containing WEAs (0, 0.7, 1.4, 2.8, 5.6, 11.2, and 22.4 %) for 15 days, respectively. The findings demonstrated that appropriate supplementation of WEAs increased feed intake and weight gain, as well as the activities of lipase, γ-glutamyl transferase, and alkaline phosphatase in digestive organs of carp. Based on broken-line regression analysis of weight gain and feed efficiency, the optimum WEAs supplementation for carp were 1.476 % and 1.478 %, respectively. Appropriate supplementation of WEAs decreased oxygen consumption rate (OCR) under hypoxia condition as well as plasma ammonia and glucose contents, increased hypoxia durative time (DT), plasma total protein contents, and glutamate-pyruvate transaminase and glutamate-oxaloacetate transaminase activities in carp's muscles, gills, or hepatopancreas. Based on DT and OCR broken-line regression analysis, the optimum WEAs supplementation for carp were 2.610 % and 2.605 %, respectively. Furthermore, appropriate supplementation of WEAs decreased malonaldehyde and hydrogen peroxide contents and increased the activities of catalase, anti-superoxide anion, superoxide dismutase, anti-hydroxyl radical, and glutathione peroxidase as well as reduced glutathione content in fish gills, muscles, or digestive organs. Overall, our current study suggests that dietary appropriate supplementation of WEAs improved growth performance that closely related to the antioxidant capacity as well as the digestive and absorption functions in the digestive organs, and enhanced hypoxia tolerance that attributed to the antioxidant capacity and metabolism of proteins and carbohydrates in the respiratory organs of Jian carp. Therefore, WEAs can serve as a natural inhibitor of hypoxic stress in fish.