Macro In Situ Results
from the University of Wisconsin - Trial 1

Compliments of Nutrition Department

What is Macro In Situ?

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 (usually 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. We 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.

Trial Results

In this study (See Figure 1), TMF106 silage had on the average a 19% greater starch degradation in the rumen than Pioneer 3563 silage (87% vs. 73%). Hybrids were planted at two populations (24,000 and 32,000 plants/acre) with similar findings for both populations (TMF™ silage had greater starch degradation). 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-SpecificSM TMF hybrid, so he/she can make the necessary adjustments to the ration. You can contact our Nutrition Department or call 1-800-MYCOGEN (1-800-692-6436) if you have any questions.

Figure 1