Adverse growing conditions such as drought can result in high nitrate levels in forage plants and the potential for toxicity for cattle. University of Nebraska Extension specialists recommend testing suspect hay or silage for nitrates, then offer guidelines for feeding the product safely.
One option is to dilute high-nitrate forages with grains or with other forages low in nitrates. Feeding grain in combination with high nitrate feeds helps reduce the effect of the nitrate content, the specialists note. Energy from the grain apparently helps complete the conversion of nitrate to bacterial protein in the rumen.
Frequent intake of small amounts of a high-nitrate feed increases the total amount of nitrate that can be consumed daily by livestock without adverse effects, and helps livestock adjust to high nitrate feeds. The specialists recommend feeding long-stem forages such as wheat, oat and cane hay that contain high amounts of nitrate in limited amounts several times daily rather than feeding large amounts once or twice daily.
A balanced ration tends to reduce problems from nitrates in the ration. The adverse effects of high-nitrate forages appear to be greater if the ration is not properly balanced. Make sure the ration is balanced nutritionally for vitamins A and E, macro minerals and trace minerals.
In addition to harvested forages, there is some risk to livestock grazing pastures with high nitrate levels. Nebraska Extension specialists suggest the following management practices to reduce the risk of livestock losses to nitrate toxicity.
- Don't overstock suspected pastures.
- Don't strip-graze suspected pastures.
- Provide other feeds that contain little or no nitrate during grazing.
- Graze suspected pasture during the day and remove at night the first week to reduce the amount of pasture consumed and to acclimate cattle.
- If possible, don't graze suspected pasture until one week after a killing frost.
- Observe livestock frequently when they begin grazing a new pasture that is suspected of nitrates to detect any signs of nitrate toxicity.