Short Communication: Estimation of Plasma Osmolality from Plasma Electrolytes, Glucose, and Urea in Calves

¹ School of Veterinary Medicine, Azabu University, Fuchinobe, Sagamihara 229-8501, Japan

Plasma osmolality estimated from plasma concentrations of Na⁺, Cl^-, K⁺, glucose, and urea was compared with measured osmolality in preweaned Holstein calves. When calves (n = 5) were fed only milk replacer after fasting for 24 h, measured osmolality fluctuated almost in parallel with estimated osmolality during the 8-h period after feeding, although estimated values were about 90% of measured values. When calves (n = 5) were fed only calf starter after fasting for more than 16 h, measured osmolality did not parallel the estimated osmolality during the 8-h period after feeding. Some factors depressed measured osmolality in the first 2 h.

Key Words: plasma osmolality • calves

Submitted on October 13, 1999
Accepted on February 2, 2000