Feed costs represent the largest annual operating cost for most commercial cow-calf enterprises.
In order to maintain an optimum balance between feed costs and production, feeds must be analyzed and these analyses used to formulate rations and/or supplements, according to Rick Rasby and Jeremy Martin with the University of Nebraska-Lincoln.
Feedstuffs vary widely in nutrient concentration due to location, harvest date (maturity), year, and other management practices. Tabular values may be used if necessary, but it is important to remember that they are average values and that significant variation exists. On a dry matter basis, energy can easily vary ±10%, crude protein ±15%, and minerals by a much greater margin.
Once a feed sample has been collected properly (see Sampling Feeds for Analysis), it can be analyzed for nutrients. Most commercial laboratories offer standard feed tests for forages, grains or total mixed rations. Analyzing cattle feeds for moisture, protein and energy is recommended. Furthermore, you may wish to identify key minerals or minor nutrients of interest. Typically, results are reported on an as-is and dry matter basis. Nutrients should always be balanced on a dry-matter basis because nutrient requirements for beef cattle are reported on a dry-matter basis. After formulation on a dry-matter basis, values can be converted to an as-is basis (using the moisture content of the feed) to determine the actual amount of feed (as-is) that should be fed.
Feedstuffs can be analyzed using traditional wet chemistry technique or near infrared reflectance spectroscopy (NIR). Samples can be analyzed more quickly, and usually cheaper, using NIR. However, NIR is only useful for feedstuffs and ingredients that have been well characterized using wet chemistry. Therefore, be sure to ask the laboratory if their database for your particular sample is extensive enough to ensure accurate results, particularly if you are analyzing less common feedstuffs.
The primary focus of this module is on understanding and applying the results from a commercial feed analysis. Use this chart to list common nutrients and the units in which they are reported.
Download Feed Ingredients and Their Units of Measure & Feed Analysis Terminology and Explanations