Influence of the in vivo method and basal dietary ingredients employed in the determination of the amino acid digestibility of wheat distillers dried grains with solubles in broilers

As distillers dried grains with solubles (DDGS) become increasingly available, it is important to determine their nutritional value for precise feed formulation. The accurate determination of digestibility is crucial, and it is known that the methods used will affect the values obtained. An experiment was designed to determine and compare the standardized ileal digestibility (SID) of amino acids from wheat DDGS using a semisynthetic diet and a difference method using 4 further diets based on corn, wheat, corn DDGS, and wheat DDGS. Eighty 1-d-old male broilers were fed a commercial starter diet until d 21. Between d 21 and 23, they were fed test diets in order to adapt to those diets before the trial took place between d 24 and 27. The trial period took place between d 24 and 27. Feed intake was measured, excreta collected, and at d 27, all birds were culled and ileal digesta was collected for the determination of apparent ileal digestibility and SID of amino acids. Values determined were similar to those reported elsewhere in the literature, although SID values for lysine were particularly low, being 0.26, 0.27, or 0.32, measured in semisynthetic, corn, or wheat diet backgrounds, respectively. It appeared that diet type employed was influential in the values obtained. The SID values for methionine, cysteine, methionine plus cysteine, and arginine were significantly lower (P < 0.05) when measured in semisynthetic diet backgrounds than wheat- or corn-based diets. It appears that dextrose and possibly purified starch have a detrimental impact on the broiler digestive tract. This may affect all digestibility methodologies in which such a diet base is used.