Macro In situ Results from The University of Wisconsin Second Trial

Compliments of Nutrition Department

The macro in situ technique is a new method Mycogen Seeds is using to estimate corn silage starch degradation in the rumen. Samples of silage are placed as is � without drying or grinding � into polyester bags and incubated in the rumen of cannulated dairy cows for a period of time (16 or 24 hrs). A rumen cannulated cow has an opening on her side used to reach inside her rumen and introduce samples. Mycogen has been working on this new technique in cooperation with some Universities. Researchers feel that the standard method of drying and finely grinding silage samples before analysis for ruminal starch degradation eliminates differences among hybrids due to kernel texture, moisture, starch type or other factors. When the sample is finely ground, any type of starch could potentially be degraded by the rumen microbes because of the reduction in particle size of the grain and removal of barriers to digestion, such as a harder seed coat or a harder endosperm.

TMF silage had on the average 12.5% greater starch degradation in the rumen than the dual-purpose silage it was compared to in this study. It is important from a ration balancing point of view to consider starch availability in the rumen. Routine lab results do not include starch degradation, so TMF and other silages will look similar on paper. The calculated energy value on the report will not be corrected for this increased energy availability and more grain than necessary might be pulled into the ration by the computer. This could lead to less than optimal use of the silage and potential rumen health problems. Please make sure your nutritionist is aware that you planted a silage-specific TMF hybrid, so he/she can make the necessary adjustments to the ration. You can contact our nutrition department at http://www.mycogen.com or 1-800-MYCOGEN (1-800-692-6436) if you have any questions.

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