Effects of dietary vitamin E on the growth performance, antioxidant status and innate immune response in juvenile yellow catfish (Pelteobagrus fulvidraco)

A 12-week feeding trial was conducted to evaluate the effects of dietary vitamin E on growth performance, antioxidant status, innate immune response and resistance to Aeromonas hydrophila for juvenile yellow catfish, Pelteobagrus fulvidraco. Six practical diets were formulated to contain all-rac-alpha-tocopheryl equivalents of 8.9 (the basal diet), 19.6, 27.0, 39.7, 77.6 or 156.9 mg kg(-1), respectively. The results indicated that weight gain (WG), specific growth rate (SGR), feed efficiency (FE) and protein efficiency ratio (PER) were significantly influenced by the dietary vitamin E levels, the maximal WG, SGR, FE and PER occurred at fish fed the diet containing 39.7 mg kg(-1) vitamin E. Fish fed the diet containing 8.9 mg kg(-1) vitamin E had lower HSI than those fed the other diets. Red blood cells, leucocytes, hemoglobin, glucose and total cholesterol concentration in serum were not significantly influenced by the dietary vitamin E levels. However, fish fed the basal diet had lower hematocrit and higher triglyceride concentration in serum than those fed the diets with vitamin E supplementation. Moreover, fish fed the basal diet had lower activities of superoxide dismutase and catalase in serum than those fed diets supplemented with vitamin E. Malondialdehyde (MDA) concentration in serum decreased significantly when dietary vitamin E levels increased from 8.9 to 39.7 mg kg(-1). Fish fed the diet containing 39.7 mg kg(-1) vitamin E had higher lysozyme and respiratory burst activities in serum and the phagocytic index of head kidney than those fed the other diets. The challenge test with A. hydrophila revealed that fish fed the basal diet had lower cumulative survival than those fed diets supplemented with vitamin E. Based on two slope broken-line regression of SGR and lysozyme activity against dietary vitamin E levels, the optimal requirement of dietary vitamin E in juvenile yellow catfish was estimated to be 33 and 46 mg kg(-1) diet, respectively. Statement of relevance: The manuscript addresses the effect of dietary vitamin E on growth performance, feed utilization, antioxidant status, innate immune and resistance to pathogen. Although this study investigated a common nutritional research topic, it still had some how research originality because such nutritional topic has not been studied in yellow catfish yet. The results give some valuable data for this fish species. What's more, the information obtained from the present study would be helpful in developing commercial diets for this species. (C) 2016 Elsevier B.V. All rights reserved.