Macro In situ Results from
the University of Wisconsin –
Effect of Maturity at Harvest and Crop Processing
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 (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.
Trial Results
The charts below summarize starch degradation results. Various types of
hybrid were tested in this trial, including TMF�
Silage-Specific� , dual purpose, high oil, Bt, waxy.
Hybrids were harvested at three stages of maturity -early dent, 1/2 milk line
and black layer - with or without processing. Whole plant moistures were 73.3,
66.2, and 60.9%, for early dent, 1/2 milk line and black layer silage,
respectively. There was a reduction in starch degradation with increasing silage
maturity (Chart 1). When silage was processed there was an improvement in starch
degradation (Chart 2). The increase in starch degradation due to processing was
significant at 1/2 milk line and black layer stages of maturity, but not at
early dent (Chart 3). You can contact our nutrition department at http://www.mycogen.com
or 1-800-MYCOGEN (1-800-692-6436) if you have any questions.
Figure 1
Figure 2
Figure 3
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