NDSU Extension Service, Published July 27 2012
Testing forages pays dividendsFARGO - Forages for winter feed could be in short supply in areas of North Dakota experiencing moderate to severe drought this growing season.
Those shortages may force livestock producers to use nontraditional feedstuffs or hay from Conservation Reserve Program (CRP) land as a substantial portion of their animals' feed ration.
U.S. Secretary of Agriculture Tom Vilsack announced this week he is allowing CRP acres classified as abnormally dry to be used for haying or grazing under emergency conditions. Authorized emergency haying and grazing can begin in North Dakota on Aug. 2.
However, some of these forages may be low in nutritional value and high in nitrate, resulting in livestock that are undernourished or at risk for nitrate poisoning.
Having the forages tested is the best way for producers to know the quality of feed their livestock is consuming, according to Kevin Sedivec, North Dakota State University Extension Service rangeland management specialist, and Carl Dahlen, NDSU Extension beef cattle specialist.
Predicting the nutritive value of forages, such as hay cut on CRP land, as well as crop residues such as corn stalks, is difficult without having them tested by a qualified nutrition laboratory, Dahlen adds. Using book values for these types of forages can lead to inaccurate conclusions about forage quality.
Forages with the potential for nitrate toxicity include small grains such as wheat, barley and oats; late-season crops such as corn and sunflowers; and weeds such as kochia and pigeongrass. Small grains that were planted for grain but harvested for hay because of drought conditions will have a greater risk for toxic levels of nitrates.
Sedivec suggests producers collect a core sample from three to five bales from each field and send them to a reputable laboratory for nitrate level testing. An NDSU publication titled "Nitrate Poisoning of Livestock" will help producers interpret the test results. The publication is available online at http://www.ag.ndsu.edu/pubs/ansci/livestoc/v839.pdf.
Producers who have high nitrate levels should visit with their local county Extension agent for recommendations on feeding high-nitrate feeds. These feeds will have to be diluted with feeds that do not have a high nitrate content, Dahlen says.
Nutritional quality can vary dramatically with CRP hay. Nutritive quality depends on when the field was last hayed or grazed, the timing of haying relative to forage maturity, the proportion of alfalfa to grass, and precipitation.
CRP hay, as well as most grass-dominant hays, harvested in August will have a crude protein value of less than 7 percent and digestibility value of less than 50 percent. However, if the CRP growth or hay field is green when harvested or contained more than 30 percent alfalfa, nutritional quality can approach 9 to 11 percent crude protein and digestibility of more than 55 percent.
If the field is brown and dry, crude protein can be as low as 5 percent and digestibility can be less than 45 percent. If the CRP field has not been cut for three or more years and standing litter is high, the hay's nutritional quality will be well below the needs of all classes of livestock.
Minerals and vitamins, especially vitamin A, also can be deficient. Dahlen recommends producers purchase supplemental feeds to make up for deficiencies uncovered with nutrient analysis.
Testing forages will allow management decisions that improve livestock productivity and overall profitability of the ranching operation, the NDSU specialists say.
For help in interpreting feed test results and balancing rations, contact your local Extension agent. More information on forage quality also is available in an NDSU Extension publication titled "Interpreting Composition and Determining Market Value." It's online at http://www.ag.ndsu.edu/pubs/ansci/dairy/as1251w.htm.