All cereals currently used in
practical pig diets contain non-starch polysaccharides, with the most prevalent
being beta glucans and arabinoxylans.
These anti-nutritional factors reduce the nutritive value of cereals and
of the diets into which they are incorporated. Not only their digestibility is
usually less than 50% (compared to over 90% for starch and sugars), but also
their presence in the gastrointestinal system reduces the digestibility of other
nutrients in the diet. Bacteria overgrowth
level of non-starch polysaccharides also contributes to hind gut overgrowth of
bacteria and it could also upset intestinal health, leading to dysentery and
Thus, in commercial pig nutrition the presence of
high levels of non-starch polysaccharides is generally considered undesirable
and the most effective method of countering their negative effects today is the
use of specific dietary enzyme preparations that enhance the digestibility of
these anti-nutritional factors.
Of the most common cereals used, wheat
and barley are the most likely to benefit from enzymatic intervention.
Oats and rye
Although other cereals, such as oats
and rye, are also rich in non-starch polysaccharides, their use in pig diets is
either local or limited; but, nevertheless, the same principles outlined below
are also applicable for these cereals.
In contrast, more common cereals
such as maize, rice, and sorghum usually do not benefit from enzyme
supplementation because they contain relatively low levels of such
anti-nutritional factors. Barley and wheat
be noted here that in pigs the use of dietary enzymes in barley- or wheat-based
diets does not always confer positive effects in terms of enhanced growth
performance and/or feed efficiency.
This is due to the fact that the
concentration of non-starch polysaccharides varies widely depending on cereal,
variety, batch, region, and even growing conditions. The level of non-starch
polysaccharides is the highest and varies the most in barley, ranging from 11 to
19%, with beta-glucans comprising 3 to 9%!
Thus, not all cereals should
benefit the same from enzyme supplementation.Australian
For example, studies conducted in Australia clearly
demonstrated that enzyme supplementation is more likely to benefit cereals of
low quality (that is, those high in non-starch polysaccharides) instead of
cereals with an average to low level of such anti-nutritional factors (Cadogan
, 2000; see graph).
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