Evaluating poultry feedstuffs in terms of their metabolizable energy content and chemical composition

Abstract

The metabolizable energy values (ME) of 16 feed ingredients available in Australia were determined with broiler chicks of both sexes. The chickens were fed test diets in which the feed ingredients replaced dextrose in a basal diet. The mean coefficient of variation was low in each determination of ME (range 0.78 to 1.20, mean 0.94 per cent). Sex had no significant effect on the ME value of most feedstuffs with the exception of oats, where ME values were significantly higher for female than for male chicks (P < 0.05). The ME values calculated from the chemical composition of feed ingredients by means of the equations of Sibbald et al; Carpenter and Clegg; and Bolton were considerably higher than that obtained by chick assay. On the other hand ME values of cereals predicted by means of Titus's equation were similar to those obtained in this experiment and to biologically determined values of ME published in the literature. ME values of protein concentrates varied considerably when estimated either by chick assay or by chemical composition. Titus's prediction equation was considered to provide a reasonably accurate estimate of the ME value of a ration where information is available only of the chemical composition of the feed ingredients.