Macro In Situ Results
from the University of Minnesota
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, TMF94, TMF100 and TMF108 silages had on the
average15% greater starch degradation in the rumen than Pioneer 3730 silage (See Figure
1). 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
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