Evaluation of structure in rations for dairy cows - new aspect | Neue Aspekte der Strukturbewertung von Rationen für Milchkühe
2008
Steingass, H. | Zebeli, Q. | Drochner, W., Hohenheim Univ., Stuttgart (Deutschland). Institut für Tierernährung
An adequate supply of structured feed is the most crucial factor in the feeding of high yielding dairy cows. On the other hand, the evaluation and requirement systems for structure used at present are not accurate enough. In the present article, a model is presented, which was developed from comprehensive data from the literature. It is based on the deduction of a minimal rumen pH-value that is necessary to prevent the risk of sub-acute ruminal acidosis (SARA). This minimum level as daily average was found to be 6.2. As evaluation criterion for structure serves the 'physically effective NDF' (peNDF1,18mm) of the diet, which is calculated from NDF-content multiplied with the mass fraction 1.18 mm determined with the 'Penn State Particle Separator'. In relation to a pH of 6.2 a content of 31 % peNDF1.18mm is required in ration DM. In addition, the content of ruminal degradable starch and the DM-intake are included in the model, as both criteria are important risk factors for SARA and hence increase the requirement of peNDF1.18mm. This new approach allows a much better assessment of requirement and supply of structure.
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