1. Enzymes as final products
1.1. Animal-feed Industry
(Walsh et al., 1993 2)
Virtually all enzymes employed in the anymal feed industry are hydrolases
directly used as feed additives to achieve at least one of the objectives:
- Supplementation of the endogenous digestive activities of the host animal
(proteases; amylases; cellulases)
- Removal of anti-nutritional factors from some convenient but problematic
feedstuffs
(b-glucanase/ arabinoxylanase; phytase)
- To render certain nutrients more-readily available for absorption and to
enhance the energy value of cheaper feed ingredients
b-glucan and arabinoxylans of high molecular weight represent the most common forms of
nonstarch polysaccharides present in animal feed that exibit anti-nutritional effect. Both these
polysaccharides are associated with the walls of the endosperm of the seeds;
examples are b-glucan in barley and arabinoxylan in wheat . When they are dissolved in the digestive tract, their
concentrations may achieve values high enough to render digesta very viscous. The consequences
to monogastric animals which do not have these activities may be the inefficient enzymatic
degradation of the ingested nutrients and physical hindrance for their uptake. The inclusion of
degradative enzymes for these compounds in animal feeds may become economical as some more
economical cereals may be thought as ingredients.
Phytic acid is a organic compound of phosphate and is the main storage of phosphorus in plants
(60-65 % of P present in cereal grains). The lack of sufficient or adequate endogenous
phosphatase activity in monogastric animals leads to the need of inorganic phosphate addition if
phytase is not included in the animals feed. In absence of the enzyme large amounts of phosphate
would be excreted and intense pollution generated. Also, phytic acid is responsible for
complexation of minerals (iron, zinc) and if it is not destroid, insufficient mineral amounts would
be assimilated by the animals.
