INTERNAL MARKERS AS ALTERNATIVE TO CHROMIUM-III OXIDE TO DETERMINE APPARENT DIGESTIBILITY IN NILE TILAPIA

Abstract

It were evaluated five different technical procedures to determine apparent digestibility coefficient (ADC) of dry matter (DM), crude protein (CP), gross energy (GE) and ash. The aim of this study was to compare internal markers such as neutral detergent fiber (NDF), acid detergent fiber (ADF), cellulose (CEL) and hydrolysis resistant organic matter (HROM), as an alternative the external marker chromium oxide-III (Cr₂O₃), in diets for Nile tilapia (Oreochromis niloticus). Thus, it were formulated two different diets, a purified diet based in protein of albumin and gelatin and a practical diet with soybean meal as protein source. Chromium oxide-III (0.1%) was added in both diets. Eighty fish (100.0±4.3 g) were placed in net tanks to feed handling and feces collecting. The ADC of nutrients was calculate based in the level of Cr₂O₃ content in diets and feces, and compared to other internal markers using the Tukey test (P<0.05). The utilization of NDF, ADF, CEL and HROM fraction as indicators of ADC were inefficient in every analyzed variable in purified diet. However, in control diet the fractions ADF and CEL were similar to Cr₂O₃ to determine ADC of DM, CP, CE and Ash.