VPT 421: Veterinary Toxicology (2+0)

SOURCES OF NITRITE POISONING

• Nitrates are non-toxic. But in the feedstuff or in the alimentary tract they are converted into nitrites, which are toxic.
• Nitrite is 6-10 times more toxic than nitrates.

Sources

• Whey, preserved feed, fertilizers containing sodium, phosphorus or ammonia, well water and plants that contain more nitrates.
• Plants that accumulate nitrate when they grow on soils containing excess of nitrates include Amaranthus retroflexus, Brassica napobrassica, Chenopodium album, Datura sp., Tribulus sp., Beta vulgaris, Curcubita maxima, Ipomoea sp. and Solanaum sp.
• Due to the lowered activity of nitrate reductase, the nitrate content of plants will be higher on dull days and at night.
• During periods of draught, the amount of nitrate in the soil can increase greatly because of lack of leaching, reduced uptake of nitrate by plants and decomposition of organic matter.
• When draught breaks, nitrate uptake by the plants may be high especially in the first week after rain. If hungry animals are allowed access to such plants nitrate poisoning may occur.
• Water run off from fertilized fields, decaying manure and silage juices may lead to nitrate poisoning through water.