Prediction of metabolisable energy of poultry feeds by estimating in vitro organic matter digestibility
The aim of this study was to develop equations to predict the in vivo apparent metabolisable energy (AME) of poultry feeds using an in vitro method for estimation of organic matter digestibility. In this study, a total of 57 samples of feedstuffs and 23 samples complete diets for poultry were used. Dry matter (DM), crude protein (CP), crude fibre (CF), crude fat (CFat) and crude ash (CA) of the diets were determined. A modified method for estimating the enzymatic digestibility of organic matter (EDOM) was used. For the determination of in vivo ME, the rooster digestibility assay was followed. Obtained laboratory results, that is in vitro and proximate analysis values were regressed against the in vivo ME values and equations for predicting the in vivo ME of feeds for poultry have been derived. Using CA, CF, CFat and in vitro EDOM as predictors, the following equation for predicting the in vivo ME in poultry feeds was derived: ME (MJ/kg DM) = 5.46 – 0.2166 x CA – 0.0946 x CF + 0.2219 x CFat + 0.1054 x EDOM (R2 = 0.844, RSD = 1.10). Using only EDOM as predictor generated the equation: ME (MJ/kg DM) = -0.41 + 0.1769 x EDOM (R2 = 0.689; RSD = 1.63). Results show that using only EDOM as a predictor was not as accurate as when the other variables were included.
Key words: Metabolisable energy, prediction, poultry, feeds, organic matter digestibility