Nitrate NO3 accumulation

DISORDER: Nitrate Poisoning
Plant Species: Sorghums, millets, corn, oats, wheat, rye, and pigweed. (Amaranthus spp.)
Conditions: Drought (moisture stress) or cloudy (low-light) conditions prevents normal plant growth. Under this conditions, the plant accumulates nitrates (NO3) mainly in stems and lower leaves instead of converting the nitrate to protein.
Causes: Consumption of plant parts with high levels of nitrates. Toxic levels usually exceed 1%.
Mode of Action: The term “nitrate toxicity” is commonly used but the toxic principle is actually nitrite. Nitrate is converted to nitrite in the rumen. Nitrite is absorbed from the rumen converting blood hemoglobin to methemoglobin. Methemoglobin cannot transport oxygen to body tissues, so animals die from oxygen insufficiency.
Animal Symptoms: Labored breathing if detected early enough.
Treatment: Acute – treat with methylene blue
Chronic – treat with Vitamin A
Prevention: 1. Don´t graze during stress periods, monitor nitrate (NO3) levels to determine levels in forage are safe.
2. Don´t graze too short nitrates accumulates mainly in stems and older leaves.
3. Don´t feed high nitrate forage free choice.
Notes: Nitrate does notdissipate from hay like HCN (prussic acid). Once high nitrates levels are reached they stay high. (it must be diluted by feeding it mix with hay that is nitrate free and or discarded). Horses and hogs are less tolerant than ruminants.Plant samples can be sent to:

Labs report nitrate content in different forms. See Table below for conversions.

Equivalent levels of nitrate.
Nitrate Nitrate-nitrogen (NO3-N) Potassium nitrate (KNO3)
ppm1 % ppm % ppm %
200 .02 46 .0046 326 .0326
5,000 0.5 1,150 .115 8,150 .815
10,000 1.0 2,300 .23 16,300 1.63
1parts per million

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