Salt Intoxication

Salt intoxication is caused by ingestion of excessive amounts of salt (sodium chloride, NaCl). The severity of clinical signs and mortality in flocks differs depending on the amount of excess salt ingested and the age of birds. Younger chicks are more sensitive to the adverse affects caused by salt intoxication, and have a higher risk of death than older birds. Low salt intoxication levels (0.4% of diet) causes increased water intake and wet litter, where when high levels (0.9 to 1.2% of diet) of salt are ingested, more severe clinical signs are observed as well as high mortality.

The recommended salt levels in poultry feed are 0.2%. It is usually associated with chickens not having access to fresh drinking water, but there have been an increasing number of incidents that have occurred due to feed mill mixing errors, resulting in improperly mixed poultry feeds.

In 2015, there were several cases of salt toxicity incidents reported in multiple broiler and breeder flocks in Isreal that were caused by a mechanical problem in the salt dispensing system at the feed mill, resulting in excess salt in some batches of poultry feed. Another issue that occurred during this incident, is that when feed samples were sent off to the laboratory feed mill for testing, the concentration of salt in the feed was off, as their calculations were based on the chlorine (Cl) content (a test that has reduced sensitivity to salt detection), as opposed to calculating based on sodium (Na) content (which is how independent testing laboratories, accurately calculated the salt levels within the toxic feed batches).

Summary of 2015 salt toxicity incidents due to improper mixing at feed mill

Flock type	Bird age	History	Clinical signs	Feed test results
Broilers	10 to 30 days	Signs appeared 3 days after changing feed from pre-starter to starter. Total mortality rate reached about 5%.	Increased water intake Chicks on backs and pedaling their feet Severe depression Incoordination Opistotonous Severe respiratory distress	Salt levels of 0.9%
Broilers	6 to 9 days	Sudden increase in mortality. Total mortality reached 20% and returned to normal within 10 days after withdrawal of the suspected feed.	Chicks on their backs on the floor, pedaling feet Severe depression Incoordination Opistotonous Severe respiratory distress	Salt levels of 1.2%
Breeders	24 weeks	Chickens were not laying eggs yet. No mortality incidents.	Increased water intake Wet litter	Salt levels of 0.6%
Breeders	45 weeks	Drop in egg production of about 8% in 4 days. Slight increase in mortality.	Increased water intake	Salt levels of 0.7%