Apparent digestibility of diets for tambaqui with increasing levels of substitution of corn by cassava flour crueira

Abstract

This experiment was lead with the aim to evaluate the apparent digestibility of the ration nutrients for young tambaqui, with growing levels of corn substitution for the manioc flour. There were been used 336 tambaqui with 34,5 ± 6,5g medium weight. The experimental limitation was entirely combined with six treatment and four repetitions, resulting in 24 experimental unities. The ration were formulated in way that they could be iso-protein (36% PB) and iso-caloric (3500 kcal ED/kg), with growing substitution levels (0, 20, 40, 60, 80 e 100%) from corn to manioc flour, corresponding to control treatments I, II, III, IV e V respectively. Fishes were daily fed at 9 am, 1 pm and 5:30 pm, and the excrements were collected by decantation in the water column in one hour breaks. The apparent digestibility coefficient (ADC) determination was made by indirect method, being used as external marker 0,5% of chrome oxide (Cr₂O₃) incorporated to the rations. The results have demonstrated that total substitution of corn by manioc flour in young tambaqui rations does not compromise the nutrients apparent digestibility.