Xylose and Xylan Utilization by the Chick

Xylose, xylan or glucose were substituted for an equal weight of finely powdered sand in a semipurified chick diet. Xylose levels greater than 40% of the diet and a xylan level of 20% appeared to be highly toxic. Xylan yielded no useful energy to the animal; xylose yielded some energy at 20% of the diet but none at either 40 or 60%. At a dietary level of 20%, chicks gained faster when fed xylose than when fed xylan even though food intake was similar for both carbohydrate sources. It would appear, therefore, that hemicellulose (essentially a xylose polymer), whether predigested or intact, has no utility in poultry rations.