ABSTRACT
Tambaqui (Colossoma macropomum ) is one of the highly produced freshwater fish in Brazilian fish farming. However, its production efficiency associated with the refinement of diet formulations is limited due to a lack of information on nutritional requirements for certain essential amino acids such as valine. This study was designed to estimate the valine requirement of tambaqui having different body weights. A total of 720 juveniles were used in the feed trials. The first trial consisted of 360 fish with an average initial weight of 33.28 ±0.19 g, and the second trial comprised 360 fish (121.19 ±1.29 g). The trials consisted of dose-response experiments with five levels of valine (5.0, 7.0, 9.0, 11.0, and 13.0 g/kg diet) and four replicate tanks per treatment. The control diet was obtained by adding L-valine to the diet containing 5.0 g/kg diet (the first level of valine tested) to ensure it reached the diet containing 7.0 g/kg diet, corresponding to the second level tested. Analysis of variance, Dunnett’s test for comparison with the control diet, and regression analysis were performed. The results showed that the valine intake, weight gain, specific growth rate, and feed conversion ratio were significantly improved by the dietary valine (P < 0.05) in both trials. Dietary levels of valine exerted quadratic effects on body protein, body fat, body protein deposition, and nitrogen retention efficiency of tambaqui with 33 g and 121 g as body fat deposition was affected by the dietary valine level only in tambaqui weighing 33 g. Quadratic regression analysis of body protein deposition data revealed the optimum dietary valine requirement of tambaqui (33.0 g-83.0 g) and (121.0 g-277.0 g) as 11.9 g/kg diet and 9.1 g/kg diet, respectively.
Index terms:
Amazon fish; branched-chain amino acid; essential amino acid; fish nutrition
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