Evaluation of different dietary additives based on growth performance, innate immunity and disease resistance in juvenile Amur catfish, Silurus asotus

Three different dietary additives were evaluated based on growth performance, innate immune responses and disease resistance in juvenile Amur catfish Silurus asotus. Four diets were prepared by supplementing 0.4% Song-gang ® stone (SG), 0.05% Yucca meal (YM), 0.05% b-glucan (BG) in combination with 0.04% SG and 0.05% BG (SG or BG) to a basal commercial diet (control; CONT). Triplicate groups of fish averaging 4.95 ± 0.05 g were fed one of the test diets between 3 and 5% body weight for 8 weeks. At the end of the feeding trial, weight gain, specific growth rate, feed efficiency and protein efficiency ratio of fish fed SG and SG or BG were significantly higher than those of fish fed the BG and CONT diets (P<0.05). Lysozyme activity in fish fed the SG, YM, and SG or BG diets was significantly higher than those of fish fed the CONT diet. Super oxide dismutase (SOD) activity was significantly higher among fish fed the SG, YM, BG and SG or BG diets than fish fed the CONT diet. After 14 days challenge test with Edwardsiella tarda, cumulative survival rates of fish fed the SG and SG or BG diets were significantly higher than those of fish fed the BG and CONT diets. Results revealed that dietary SG or SG or BG diets had positive responses over other additives in juvenile Amur catfish. However, Song-gang ® stone is proposed to be a cheaper dietary additive contributing 0.04 cents/kg of feed based on economic point of view.