ENERGY EXPENDITURE OF BEEF CATTLE GRAZING ANNUAL GRASSLAND

Abstract

Carbon dioxide production rates of beef cows were measured by continuous infusion of NaH 14 CO 3 . Underestimations occurred when multichannel pumps were used, due to diffusion of 14 CO 2 from infusion to sampling tubes. Estimates of energy expenditure from CO 2 production varied from 1125 KJ kg 0.75 ∙day −1 when the cows were lactating, to 468 KJ 0.75 ∙day −1 when dry. Key words: Grazing cattle, energy expenditure, carbon dioxide production