As the drought conditions continue, things you need to be aware of concerning your
livestock and pastures.
Nashville, Ark. – Drought can be an issue for more than just yield losses in your hay fields. Major problems that come with drought are the accumulation of nitrates or prussic acid in Johnsongrass, sudan grass, and sorghum-sudan hybrids. Nitrates do not break down when hay is harvested. Even Bermuda grass can be excessively high in nitrates if a high rate of fertilizer is applied to the grass without an adequate amount of water. The water will stimulate plant growth which converts the nitrates into protein. Nitrate-nitrogen levels above 700 ppm can be detrimental to the health and productivity of a herd. Forty to sixty percent of Johnson grass and sorghum-sudan hybrids tested at the UA diagnostic lab exceeded 700 ppm nitrate-nitrogen. Pregnant animals do not need levels above 700 ppm, and levels above 2100 ppm may be lethal. A nitrate test would be a wise investment to protect your herd against any potential nitrate toxicity problems. A nitrate test costs $6 per sample and can be performed by the Extension Agent. The County Extension office can also offer guidelines for feeding hay high in nitrates.
Prussic acid can also be a problem with hay harvested during drought conditions. Johnsongrass, sudan grass, and sorghum-sudan hybrids take longer than other grasses to cure without the use of a mower-conditioner. Prussic acid will break down within hay, but prussic acid problems can still be observed in a herd where hay was harvested with excessive moisture. Prussic acid is also a concern after a killing frost. For plants that are susceptible to prussic acid accumulation, delay grazing after killing frost until plants are brown and dry.
Livestock producers should pay close attention to the water requirements of their herd. A mature cow will consume approximately 18 gallons of water per day in 90-degree weather. Without rain, the volume of a pond will diminish from consumption and evaporation. As the water level in ponds gets low, the water quality will also diminish. Low water quality can result in the accumulation of contaminants such as nitrates and salts to levels that can lead to problems with herd health and performance. The safe upper limit for nitrates in water for livestock is 100 ppm nitrate-nitrogen. Cattle during late gestation, or early lactation and stressed cattle are more susceptible. If water quality is a concern, producers can send in a water sample for analysis and should begin to identify additional water resources for their livestock. Producers considering supplying water through a tank system should make sure that the volume and flow rate are capable of meeting the demands of the livestock. A helpful conversion for tank capacity is 1 cubic foot is equal to 7.5 gallons.
For more information, you can contact the Howard County Extension office at 870-845-7517 or find helpful fact sheets on our website at www.uada.edu. The Cooperative Extension Service is part of the University of Arkansas System Division of Agriculture.
By Dawson Bailey
County Extension Agent - Agriculture
The Cooperative Extension Service
U of A System Division of Agriculture
Media Contact: Dawson Bailey
County Extension Agent - Agriculture
U of A Division of Agriculture
Cooperative Extension Service
421 N. Main Nashville AR 71852
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