ENERGY EXPENDITURE OF BEEF CATTLE GRAZING ANNUAL GRASSLAND

Abstract

Carbon dioxide production rates of beef cows were measured by continuous infusion of NaH14CO3. Underestimations occurred when multichannel pumps were used, due to diffusion of 14CO2 from infusion to sampling tubes. Estimates of energy expenditure from CO2 production varied from 1125 KJ kg0.75∙day−1 when the cows were lactating, to 468 KJ0.75∙day−1 when dry. Key words: Grazing cattle, energy expenditure, carbon dioxide production