Determination of apparent and true dietary fatty acid digestibilities and metabolisable energy using ileal digesta and excreta from broiler chickens

Four-week-old broilers were fed a semi-purified low-fat diet containing 0.6 g lipid kg−1, or the same diet supplemented with between 15 and 60 g kg−1 of either soyabean oil or a mixed animal-plant acid oil. Endogenous fatty acid losses were measured using the low-fat diet and apparent and true fatty acid digestibilities determined using digesta from the lower ileum and excreta. The contributions of endogenous losses were of minor significance with both oils, and microbial lipid synthesised in the large intestine and caeca was unimportant in broilers fed the soyabean oil. However, significant differences between digestibilities determined at the lower ileum and in excreta were observed in broilers fed the acid oil. Corresponding significant differences in the calculated metabolisable energy value of the acid oil were obtained.