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Forage Testing Provides Useful Information

Posted Jul. 10, 2007

With abundant rainfall in the spring of 2007, hay supplies are in much better shape than in 2006. Quality of the forage, however, may be quite varied. Much of the hay baled this spring was either mature when hayed or may have been rained on during the haying process. Therefore, testing the quality of your hay becomes extremely important. Some hays will require little, if any, supplement, and other hays will require substantial supplementation to meet the nutritional requirements of the livestock being fed.

Table 1 illustrates the differences in nutritional requirements of different classes of cattle.

Crude protein (CP) and total digestible nutrients (TDN) requirements change with physiology changes for the different classes of cattle. What does this mean to a cattle producer? Let's look at an example to demonstrate the differences from a nutritional perspective. We have three hays on hand, as represented in Table 2, along with the forage analysis on a dry matter basis (DM).

Table 3 shows the daily nutrient content of the hays (expressed in pounds DM) when fed ad lib (constantly available to the livestock) and the nutrient surplus or deficit (expressed in pounds DM) for each hay relative to each class of cattle.

As one can infer from the table, each hay has a different utility. The alfalfa hay in this example is almost too good to feed ad lib to most of the classes listed and would be better used as a supplement to the lower quality bermudagrass hay. The first cut bermudagrass hay that was rained on only meets the daily nutritional requirements of the dry, pregnant cow. If fed to the other classes of livestock, supplement would be required for both CP and TDN just to maintain the condition of the cattle.

The second cutting bermudagrass hay meets the CP nutritional requirements for all classes of cattle except the stocker calf and the TDN requirement of only the dry cow class. With the forage analysis, not only do we know which hays require supplementation, we also can calculate how much supplement is required to maintain or add weight to any class of livestock we are feeding.

Therefore, take the time this year to have your hays analyzed for crude protein and energy (TDN) either after you have them stored or prior to purchase, if you are purchasing hay. The forage analysis will also assist you in determining the value of the hays should you be purchasing or marketing hay.