Nutritional value of root and leaves of cassava for Nile tilapia

Abstract

The aim was to evaluate the nutritional value of the root and leaves of cassava (Manihot sculenta) for juveniles of Nile tilapia (Oreochromis niloticus). Three diets were prepared, a reference and two test diets. The first tested diet contained 50.0% of cassava root and 50.0% of reference diet and the second one consisted of 30.0% of cassava leaf meal and 70.0% of reference diet. Moreover, in every diet was added 0.1% chromium oxide-III (Cr₂O₃) as inert marker. Sixty juveniles (100.0 ± 9.0 g) were accommodated in cages (10 fish/cage) for feeding and feces collection. During the day, these cages were maintained in a feeding tank (250 L), one tank for each treatment, where the fish were fed until apparent satiation. After the aforementioned feeding period, they were transferred to a fecal collection tank, where they remained until next morning. The collected feces were frozen and dried for analyzes. The apparent digestibility coefficients (ADC) were calculated on basis of Cr₂O₃ concentration present in diets and feces. The ADC of reference diet for DM, cassava leaf and root were, respectively, 85.23%, 81.22% and 91.44%; CP to 97.35%, 73.37% and 91.46% and for the GE, to 87.70%, 64.70% and 92.20%, being the values obtained for the diet with cassava root significantly higher (P<0.05). Summarizing, root and cassava leaves can be used as alternative ingredients for compose balanced diets for Nile tilapia juveniles.