Abstract
The sodium and potasium concentrations in the mixed and parotid saliva which were taken from the steers exposed to the high environmental temperatures and humidities were determined to assume the extent of aldosterone secretion as a measure of the environmental stress.
1) Under the environmental conditions of 42°C in temperature and 80% in humidity, the Na: K ratios in both of mixed and parotid salivas were decreased, suggesting increased aldosterone secretion.
2) Under the environmental conditions of 36°C or 33°C in temperature and 80% in humidity, the Na: K ratios of mixed saliva both decreased. On the other hand, the Na: K ratios of parotid saliva were remained unchanged in both environmental conditions.
3) When the steers are exposed to such severe heat stress as this experimental conditions, the salivary Na: K ratio was affected not only by the increased aldosterone secretion, but also by the reduced parotid saliva secretion and other unknown factors, depending on the extent of the stress.
