Ruminal degradability of different starch sources and duodenal flux of starch

Cereal grains are the major component of diets used for intensive production of livestock. The primary nutrient in grain is starch, which represents 60 to 80% of most cereal grains. There are large differences in rumen degradability of starch from different starch sources. For most grain (wheat, barley, oats), except corn and sorghum, 90% or more of starch is fermented in the rumen. The varying degradation rates in the rumen can be attributed not only to the chemical nature of the starch itself, amylose or amylopectin, but also to the endosperm structure of grain and the protein matrix, in which starch granules are embedded. The nylon bag technique involves determination of the disappearance of feeds placed in the bag and incubated in the rumen of a fistulated animal for specified periods. The results simulate the fermentation normally occurring within the rumen. The method has been used to some extent as an alternative to in vivo trials for determining digestibility of forages as well as concentrates. A lot of experiments have been carried out to determine the rumen starch degradability of different grain varieties and also the effect of different processing methods.