Animals most affected
Poisoning by straw treated with ammonia either in a digester or under plastic sheets
(to increase the non-protein nitrogen and the digestibility of the straw or to aid
storage). Occurs through:
ingestion of too great a quantity of this type of fodder;
ingestion of poorly treated straw (the straw becomes too rich in ammonia).
Direct transfer of ammonia across the alimentary tract and rumen, causing hyperammoniaemia
and an alkalosis. Increase in lactacidaemia leading to a possibly fatal acidosis.
Fasting, an abrupt change of diet, a low water intake or lack of water all increase
the likelihood of poisoning. A diet based on concentrates reduces the severity of
Note:frequently with poorly treated straw (i.e. when kept under cover), the conditions
encourage the growth of fungi responsible for producing mycotoxins.
Toxic doses vary according to the level of protein in the feed:
where protein > 12% and
soluble nitrogen > 60%
Rapidly fatal (within minutes) and without any clinical signs.
Predominantly neurological, with:
hyperexcitation, grinding of the teeth, tremor;
opisthotonos, generalize& muscular contractions;
eventually death or an acidotic coma.
degeneration of the liver and kidneys.
If large quantities are ingested:
correct the alkalosis: use cold acidulated water (diluted vinegar);
correct the acidosis (rarely achievable) using iv 1.4% sodium bicarbonate, 1-21/animal.
supply a readily fermentable energy source (500 g lactose in solution given over
promote intestinal bacteria to increase their growth and metabolism (orotic acid
10 g, twice a day for 5 days).
The toxic components break down and disappear rapidly:
ruminal contents: freeze the samples immediately;
suspected material or straw: store in a waterproof container.