(chronic intoxication)


[affected.gif] Animals most affected
Cattle, sheep, (all animals)


[etiology.gif] Etiology
Ingestion, over a prolonged period, of water which has been badly polluted by nitrates or nitrites (contaminated by chemicals and organic fertilizers, domestic waste waters, industrial effluents (e.g. food processing units, dairy factories), etc.).
Regular and frequent ingestion of plants or fodder rich in nitrates (e.g. rape seed cabbage or other brassica, rye grass) or of hay contaminated with wild plants (amaranthus, chenopodium or fat hen), which all have a high nitrate content.
Note: the manuring of soils significandy increases the nitrate levels in plants.


[toxic.gif] Toxicity
Toxic doses depend upon the nature of the diet.

In general, oral intake of nitrates:
TD cattle 0.9-1.8% of the diet

However, if the diet is balanced with the levels of nitrates not exceeding 3% in hay or 6% in feed concentrates, toxicity does not develop.
TD cattle 9(l00 mg/l in drinking water)

Reference note
recommended levels of nitrate in drinking water: 20 mg/l;
maximum levels permissible in drinking water: 50 mg/l.



[clinical.gif] Clinical features
The following have been attributed to chronic nitrate poisoning.

Effects on the reproductive system

Effects on the newborn

Effects upon the endocrine system

Effect on vitamin A