Soybean is the most widely used vegetable protein
source for monogastric animals and is the most prevalent
legume/oil seed crop in the world (FAO, 2008). However,
soybeans contain nearly as much carbohydrates as protein
yet the nutritional and/or anti-nutritional activities of these
carbohydrates in animal feed are quite often ignored.
Poor growth performance has been observed when
broilers were fed diets containing soybean meal (SBM) as
the sole dietary protein source (Irish and Balnave, 1993). It
was observed that the poor growth of broilers fed SBM as
the sole protein source was more pronounced with meals
processed in Australia compared with the meals processed
in USA. This response was assumed to be related to the
higher fiber content of Australian processed meals (Irish
and Balnave, 1993). The poor growth performance could
not be explained by the digestibility or the amount of
essential amino acids, or the process of heat treatment of the
SBM tested. A significant relationship was observed
between the water-soluble xylose content of the soybean
meals and the improvement in weight gain obtained when
sunflower meal replaced some of the soybean meal.
Measurement of free sugars in the supernatant of the digesta
in the ileum indicated that the stachyose derived from the
oligosaccharides of SBM appeared to exert an anti-nutritive
effect when SBM was present at high concentrations as the
sole protein source in broiler diets (Irish and Balnave, 1993)