Dietary biotin requirement for growth of juvenile zebrafishDanio rerio(Hamilton-Buchanan)

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This study was conducted to estimate the dietary biotin requirement for maximum growth of zebrafish Danio rerio. Six isonitrogenous and isocaloric purified diets containing 0.031 (biotin-unsupplemented diet), 0.061, 0.263, 0.514, 1.741 and 2.640 mg biotin kg−1 diet were fed in triplicate tanks for a total of 12 weeks to juvenile zebrafish (initial mean body mass 0.13 ± 0.001 g). From 4 weeks of feeding, fish fed diets with ≤0.061 mg biotin kg−1 showed biotin deficiency signs, such as retarded growth and skeletal deformity, was observed on some dead fish. At the end of the study, gill disorders were observed on some fish and liver glycogen accumulation were also observed in fish fed these diets. Fish fed the biotin-unsupplemented diet exhibited a lower final body weight, protein efficiency ratio and feed utilization than the fish fed the biotin-supplemented diets, whereas the highest values were observed with the diet containing 0.51 mg biotin kg−1 diet (P < 0.05). A linear relationship (r2 = 0.77; P < 0.0001) was observed between whole-body biotin content and dietary biotin level. A broken-line analysis indicated that the optimum dietary biotin content for maximal growth expressed as final body weight is 0.51 mg kg−1 diet.