With dry weather in western KY, be cautious of the potential for nitrate poisoning before grazing or harvesting drought stressed summer annual forages like sorghum-sudan, pearl millet or silage corn. Several management strategies are available to reduce the risk of nitrate poisoning.
- The majority of cases in KY come from cattle eating fertilizer, so store properly and clean spills.
- Avoid grazing warm season grasses fertilized with excess manure or high N rates when growth slows from drought, frost, hail, or herbicide exposure.
- Corn silage should be properly ensiled at least 3 weeks and tested for nitrates before feeding.
- Mix high nitrate forage with forage known to be low.
- Feeding low nitrate forage or hay before turning cattle on to high nitrate forages.
- Splitting grazing times will also allow nitrates to be utilized properly by the rumen microflora.
- Cattle can increase their tolerance to nitrates in their diet with time. Provide time for adaptation.
- To aid in increasing this tolerance, the diet should be sufficient in vitamin A and trace minerals.
- Delay harvest of high nitrate forages until nitrate levels are safe or raise the cutter bar to 18 inches.
- When in doubt, take the time to send samples for nitrate testing before introducing cattle to the pasture.
- Consult your county Extension agent for information on sampling for nitrates, conducting a quick field test, and/or to send samples for testing.
For more information see UK publication “Nitrate Poisoning”.