Effects of Feeding Different Amounts
of Corn Silage in the Ration
Compliments of Nutrition Department
In this trial conducted by the University of Minnesota,
high-producing dairy cows were assigned to 5 ration treatments balanced on NDF from
forage. Dietary forage NDF (NDF from corn silage and hay) ranged from 18% to 26% of the
ration dry matter. Rations consisted of TMF100 corn silage, shelled corn, alfalfa hay,
soybean meal, distillers dried grains, soyhulls, wheat midds, blood meal, tallow,
vitamin/mineral mix and rumen inert fat (Megalac®). The percentage of every ingredient in
the ration – with the exception of corn silage, corn grain and Megalac® - was kept
constant. As the percentage of corn silage in the diet increased, the percentage of corn
grain decreased and the percentage of Megalac® increased. The 18% Forage NDF diet
contained 22% corn grain and 0% Megalac® compared to 0% grain and 1.8% Megalac® in the
26% Forage NDF diet. Therefore, all the corn grain was replaced with TMF100 silage and
Megalac® in the highest forage ration.
Authors reported no differences in milk production (96 lb.
average) among the five dietary Forage NDF treatments. Dry matter intake generally
decreased as NDF from forage increased in the diets. Cows fed the 0% corn grain and 1.8%
Megalac® (63:37 forage to concentrate ratio) were the most efficient at converting feed
to milk at 1.8 lb. of milk per pound of dry matter fed.
It was interesting to observe no differences in milk
production among diets. Diets had similar energy levels due to the increased percentage of
Megalac®. However, the rumen microbes do not utilize fat as primary source of energy. It
appears that TMF100 provided enough substrate for the rumen microbes to grow, so that milk
production was not compromised. One could envision that in the long term, a ration with
greater forage percentage would result in a healthier rumen. There should be an
advantage in feeding more TMF corn silage and less corn grain in the ration like it was
done in this study.
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