The use of enzymes in poultry diets

Despite their widespread use in poultry diets, the ways in which enzymes function are still not fully understood. Whilst it is agreed that a reduction of intestinal viscosity is the most likely mechanism when the appropriate enzymes are used in barley- and rye-based diets, some animal nutritionists claim that this is not so important in enzyme supplemented wheat-based diets. This paper, which attempts to place the relevant pieces of information into context, indicates that, even in the case of wheat-based diets, intestinal viscosity is a major factor limiting bird performance. Thus, in wheat fed birds the use of enzymes to reduce intestinal viscosity is likely to be the most effective method for improving performance. Data are also presented which, contrary to popular belief, indicate that most of the beneficial effects resulting from the feeding of xylanase-based enzymes to broilers are observed in the latter stages of the production cycle.