During periods of drought, the amount of nitrate in the soil can increase greatly because of:

• a lack of leaching;
• reduced nitrate uptake by plants;
• decomposition of organic matter.

When a drought breaks, nitrate uptake by plants may be high, especially in the first week after rain. If hungry animals are allowed free access to such plants, stock losses from nitrate/nitrite poisoning may be disastrous.

Nitrates and nitrites are closely linked as causes of poisoning. Nitrate is not always toxic to animals. When feed containing nitrate is eaten by ruminant animals, nitrate is converted to nitrite, and then to ammonia, by rumen microbes. Non-ruminant animals are unable to do this. This Primefact includes information on the following:

• What is nitrate/nitrite poisoning?
• Sources of poisons
• Animal susceptibility
• Signs of poisoning
• Post-mortem findings
• Diagnosis
• Treatment
• Prevention.