This work by Sonja de Vries and co-workers of the Animal Nutrition and Food Chemistry Group of WUR, conducted within the framework of the Carbohydrate Competence Centre, illustrates the complexity of the measurement of apparent ileal and total tract digestion in broiler chickens using marker techniques.
Using a dual marker technique (Cr2O3 and Co-EDTA) and quantitative faecal collections as a reference, de Vries illustrates that separation of digesta fractions occurs, particularly in the caeca (more soluble material), but also at the terminal ileum. Estimates of apparent total tract digestibility were lower when calculated using the marker method compared with the total collection method, particularly in high-fiber diets. Using Cr2O3 as a marker, differences were relatively small. When estimating apparent ileal digestibility, separation of marker and digesta resulted in unrealistically high estimates for the digestibility of dietary fibre (54 to 66%), greatly exceeding apparent total tract values. The data illustrate that fractionation of digesta, particularly in high-fiber diets, complicates accurate apparent ileal digestibility measurements in broilers, regardless of the choice of markers used.
The full paper is published in Poultry Science 93: 2010-2017, 2014. S. de Vries, R. P. Kwakkel, A. M. Pustjens, M. A. Kabel, W. H. Hendriks, and W. J. J. Gerrits Separation of digesta fractions complicates estimation of ileal digestibility using marker methods with Cr2O3 and cobalt-ethylenediamine tetraacetic acid in broiler chickens.