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Virginia Cooperative Extension - Knowledge for the CommonWealth

Evaluate your forage inventory now!

Dairy Pipeline: November 2005

Robert E. James Extension Dairy Scientist, Dairy Nutrition (540) 231-4770 email:

By now all forages have been harvested and it's time to evaluate the inventory. In this part of the country, the primary forage is corn silage with smaller amounts of alfalfa hay or haylage, small grain silages and grass hay. Most dairy producers rely on previous experience in planning what to do next year. This approach can result in some real surprises if there are big changes in forage quality and quantity. Several examples come to mind. . .

This year we had erratic rainfall with large effects on corn growth depending on stage of maturity when rains came. One producer harvested some excellent quality corn silage, with perfect dry matter (32%), low fiber (22% ADF) and high energy. However, yields were lower than previous years. Last year the yields were higher, but quality was lower (38% DM, 29% ADF). Last year's ration called for 55 lb. of corn silage and a substantial amount of corn grain. This year's ration called for 20 lb. more corn silage and less supplemental corn grain. This was a healthier ration with more forage dry matter and lower cost too! However, the new ration would require 450 more tons of corn silage for his 150 cow herd! This feeding program would exhaust silage inventory 80 days sooner than last year.

It was one of those years when nothing worked well for another producer. Small grain silage harvest occurred during extended wet weather. Barley silage had 22% dry matter and an undesirable smell. The largest cutting of haylage was too dry, 73% dry matter. It was very dark and smelled like caramel. Corn silage dried down fast and was ready to harvest two weeks before the custom harvester arrived. With these feeds, intake was depressed so milk production dropped considerably.

What should a dairy manager do? The poorest response is to do what was done last year and expect the same result.

  1. Estimate the amount of each forage in inventory. Allocate it to where it is most needed. Highest quality goes to the milking herd and calves. Animal numbers and the days that feed must last determine the maximum amount fed per day. Include losses due to spoilage which can range from 5% to 25%.
  2. Evaluate quality by sending representative samples to a recognized forage testing laboratory. Get a more detailed analysis of the forages which are a major constituent of your feeding program. This might include CPM analysis for an in depth description of the carbohydrate and protein fractions, minerals and microminerals. A fermentation analysis of silages can reveal problems with palatability if butyric acid is too high. In vitro NDF digestibility tests can provide a better estimated energy value of corn silage. These tests will enable nutritionists to supplement forages to make up for deficiencies. When forage quality is high, the tests can result in significant savings in feed costs. Many dairy producers are reluctant to spend $100 to $200 on these comprehensive analyses. However, improved knowledge of forage quality can result in significant savings in feed cost and/or improved milk yield.

In the former example, the dairy producer projected forage needs and located additional silage early in the year when price was more reasonable. In the second example a fermentation analysis revealed large amounts of butyric acid in the silage which can predispose fresh cows to ketosis. This forage was removed from the milking cow ration and used for older heifers. The protein levels in the alfalfa haylage were heavily discounted for heat damage and used sparingly in the milking herd ration. Finally, a test of the corn silage revealed heavy mycotoxin contamination and low NDF digestibility. A mycotoxin binder was added to the ration and brewer's grains were used to add some more digestible fiber and improve palatability of the ration. Production increased moderately, but it became apparent that the existing forages were of insufficient quality to support high milk yield. Knowing not to expect high milk production, the producer could make more realistic forecasts of farm income in the coming year.

Evaluate forage inventory and invest in tests of forage quality for effective planning of the feeding program in the coming year.

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