Digestibility of feed ingredients may influence the severity of enteric disorders in poultry. In general, poorly digested
feed results in less nutrients being available to the bird for growth and more nutrients available for gut microflora and
pathogens; this is not good. Poor feed digestibility may be due to several anti-nutritional factors in feed ingredients: 1)
enzyme inhibitors (e.g. trypsin inhibitor in underprocessed beans); 2) nonstarch polysaccharides in grains;
3) overcooked protein; and 4) poorly digested protein sources (e.g. keratin in feather meal or hair). In turkeys, a
significant portion of the protein in starter diets comes from soybean meal. Too much dietary soybean meal (>30% of
the diet) may cause malabsorption or maldigestion because of the high dietary level of the osmotically active
non-starch oligosaccharides, galacto-mannans, raffinose and stachyose. Similar problems exist in feeding high amounts
of grains containing non-starch polysaccharides such as -glucans, arabinoxylans, and other pentosans. Poultry,
especially young ones, do not have the innate enzyme capability to digest these carbohydrates, which ultimately
increases microbial fermentation. Moreover, these compounds alter gut digesta viscosity, which adversely affect
digestion and nutrient absorption, or they indirectly irritate the gut by increasing microbial fermentation. Dietary
supplementation of enzymes, such as -galactosidase or an endomaninnase for soybean meal, -glucanase for barley, and
arabinoxylanase for wheat may alleviate the adverse effects of excess non-starch polysaccharides on birds subject to
enteric disease.