Importance of feed testing your forage supply

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Sarah Sommerfeld, PAg, Regional Forage Specialist, Outlook

Saskatchewan Ministry of Agriculture

 

Variability of hay quality in a growing season can be high, even under optimal conditions. Plant maturity at the time of cutting is the single largest factor in determining forage quality. As forage plants mature, the protein content, digestibility and amount of forage the animal can consume decreases. Moisture conditions and nutrient status of the soil can affect the protein and mineral content of the forage. Weathering of hay in the windrow, leaf retention during baling and moisture content at time of baling are some other factors that can affect the quality of the forage.

Feed testing and the proper interpretation of results can help producers decide if forage resources available on farm will meet requirements of the cow herd and if supplementation of energy, protein or minerals will be required for the upcoming winter feeding season. Each type of forage should be submitted for a feed test. For instance, if a producer harvests an alfalfa/grass mixed stand, a pure alfalfa stand and barley greenfeed, samples from each of these fields should be collected and submitted for feed analysis separately.

When submitting forage samples for feed testing, it is important to collect a sample that is representative of the forage supply. Samples should be taken from a number of bales. A hay probe is the best tool to use to collect forage samples. A hay probe allows for a cross section of the bale to be sampled, collecting both stems and leaves. When using a hay probe, samples should be collected on the round side from the lower half of the bale, where there is a minimal amount of weathering. Hay probes are available for use from each Saskatchewan Ministry of Agriculture Regional Office.

Choosing the most appropriate feed analysis is important. A standard forage quality test provides information on moisture, energy, fiber and mineral content. Feed test results are reported on an “as fed” and a “dry matter” basis. Dry matter basis means that all the moisture has been removed, which is important when comparing nutrient content between forages or other feed ingredients.

The fiber portion of forage is made up of three components: lignin, cellulose and hemicellulose. Lignin and cellulose are relatively indigestible and are referred to as acid detergent fiber, or ADF, in a feed analysis. The ADF content of forage is used to determine the digestibility of the feed, or to predict the energy value of the forage. A high ADF value means more mature forage with lower digestibility and less energy available. Neutral detergent fiber, or NDF, includes both the indigestible (lignin and cellulose) and digestible (hemicellulose) fiber portions of the forage. The NDF content of forage can be used to predict forage intake by the animal. A high NDF value, above 60 per cent, means that the forage is very fibrous and bulky, indicating that intake may be limited. In these cases, the animal may not be able to physically consume enough forage to meet daily energy requirements.

If the forage crop has experienced a significant amount of weathering while in the swath or damage from heating, consider including an acid detergent insoluble nitrogen, or ADIN, analysis in the feed test. Protein availability or the amount of heat damage can be determined by measuring the amount of nitrogen bound to the fiber portion of the plant as a result of the heating. When nitrogen is bound to fiber it becomes unavailable for use by the animal. This type of feed analysis result will help to determine if a protein supplement may be required during the winter feeding season.

It is important to note that the analysis for NDF or ADIN are often available outside the standard forage quality test, so be sure to select the appropriate feed analysis package when submitting forages for feed testing.

For more information on feed testing your forage supply this fall, contact the Regional Forage Specialist at (306) 867-5559, visit the Ministry of Agriculture website at www.agriculture.gov.sk.ca and watch the web video Importance of Feed Testing or contact the Agriculture Knowledge Centre at 1-866-457-2377. For hay probe availability and use, contact your local Saskatchewan Ministry of Agriculture Regional Office.

Organizations: Saskatchewan Ministry of Agriculture

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