Raw material and nutrient lexicon

The stable starch (bXS) represents the proportion of starch contained in a feed that is not degraded by the microorganisms in the rumen of ruminants and is thus directly available in the small intestine as an energy source.Maize starchis an important example of this. Compared to other starch sources (e.g. wheat starch), maize starch is degraded in the rumen of the ruminant much more slowly and in smaller proportions. On the one hand, this relieves the rumen, and on the other hand, comparatively larger quantities of maize starch reach the small intestine directly. This stable starch leads to a higher energy utilisationthan when starch is first converted in the rumen into the precursor of glucose, intopropionic acid.

Up to now, it has not been possible to precisely determine the amount of rumen-stable starch directly available in the small intestine. In ration design for dairy cows, tabulated Dutch values for "starch resistance" have been used up to now. For maize products, however, the derivation of starch resistance is more differentiated. For example, the starch content, the T-content, the maturity, the variety, etc. have to be taken into account. It has therefore been agreed in Germany to use the following simple estimation formula for maize products to determine starch resistance: Starch resistance = starch content in % of dry matter.

Example: A maize silage with 29 % starch (in T) has a starch resistance of 29 % and thus contains 84 g resistant starch/kg T. However, the maximum starch resistance for maize products is limited to 30 %.

All previous investigations have shown that a wide range of carbohydrate contents can be successfully used in the feeding of dairy cows. Therefore, the DLG (Deutsche Landwirtschaftsgesellschaft e.V.) has compiled the recommendations for supplying dairy cows at different stages of production with carbohydrates in the total ration, as shown in the following table, on the basis of trial results and experience in feeding practice.

* fresh milking cows**
old milking cows***
kg ECM per day (1.05

0.

38% fat

0.

21% protein)/3.28)
XS = starch, XZ = sugar, bXS = resistant starch