European reference method ofin vivodetermination of metabolisable energy in poultry: Reproducibility, effect of age, comparison with predicted values

Abstract

1. Apparent metabolisable energy corrected to zero‐nitrogen retention (AME_n) was measured using the European reference procedure in 9 European laboratories. Seven pelleted diets were evaluated. AME_n was measured with adult cockerels and young birds. 2. Betweeen‐laboratory standard deviations were for dry matter (DM) 12.5 g/kg, gross energy 0.085 MJ/kg DM, Kjeldahl nitrogen 0.768 g/kg DM, AME_n (adults) 0.256 MJ/kg DM, and AME_n (young) 0.337 MJ/kg DM. Corresponding coefficients of variation between laboratories were 1.42, 0.45, 2.15, 1.88 and 2.60% respectively. 3. AME_n values of experimental diets were always significantly lower when measured with young birds. This effect was more pronounced when diets contained added fat. 4. Tallow or soyabean oil were incorporated into two basal diets at 40 g/kg inclusion rate. No significant differences were observed between AME_n values of either diet with adults or young birds, suggesting that AME_n energy values of these fats are indistinguishable at this inclusion rate. 5. Similar AME_n values were obtained in young birds by estimating nitrogen accretion, either by the difference between intake and excreta nitrogen or by measuring body weight gain. Determined AME_n values were very similar to those predicted using three different regression equations.