When it comes to uniformity of activity, legumes are particularly well suited to the use of exogenous enzymes. Economic feasibility relies on making sure we are fully aware of the nutrients involved and not wasting expensive additives on functions that the animal , or bird can handle without help. Dietary fibre can be thought of as the skeletal remains of the plant cells in the diet, which are resistant to hydrolysis by mammalian digestive enzymes. This definition distinguishes endogenous from exogenous enzymes. Endogenous enzymes are those that are produced by the animal and, in the case of digestive enzymes, secreted in the gut Amylases and proteases (such as trypsin, chymotrypsin, rennin) are thus endogenous enzymes produced by the animal. For further improvement of feedstuff digestibility, exogenous enzymes are required: phytase, xylanase and b-glucanase are well-known examples. In corn/soy diets, it is remarkable that many endogenous enzymes are used; these are normally secreted in sufficientquantities by the animal. This is all the more significant considering that corn/soy diets contain ample substrates for exogenous enzymes.
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