Extracellular Body Water of Growing Calves as Measured by Thiocyanate Space

Summary Estimates of the size of the extracellular body water compartment of growing calves were determined by observing the distribution of sodium thiocyanate. One hundred and forty-six estimates of thiocyanate space were made on 76 calves. Data were collected on heifer and bull calves up to 800 lb of body weight. Extracellular water, estimated by thiocyanate space, decreased rapidly in growing calves from about 48% of body weight at birth to about 30% at 1 yr. This decrease occurred during the first four months in heifers and in the fifth to seventh month for bulls. Thiocyanate space of young bulls tended to be higher than in heifers of the same weight. In bulls, the pronounced decline in this space coincided with the probable time of onset of sexual maturation.