THE EFFECT OF EMPTYING THE RUMEN ON THE HEAT-PRODUCTION OF WETHERS

The objective of this study was to determine the effect of emptying th e rumen on the heat production of wethers. Gaseous energy losses were measured with eight wethers (average BW 72 kg) fed two basal diets wit h or without a distal ileum gum infusion. Animal gas exchanges were de termined over two consecutive days to obtain baseline values, and also after emptying the rumens and measuring animal gas exchanges during a pprox. 2.5 h. Heat production after emptying the rumen decreased appro x. 50%, to values similar to what would be expected during fasting hea t production. Respiratory quotients decreased from around 1.0 to 0.83, indicating a drastic increase in fat utilization. Results indicate th at energy expenditure from metabolizing substrates prior to or after a bsorption from the rumen accounted for around 50% of total heat produc tion in this experiment, and that animals were able to change from a p ostpandrial state to starvation in minutes.