Effect of Postural Position and Position Changes on Energy Expenditure in Fasting Dairy Cattle

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Abstract
Four Holstein steers approximately 2 years of age were used to measure the fasting expenditure of cattle while stand- ing, lying, and during position change (standing up or lying down). Thirty-two 10-hour periods of fasting heat production were studied during which energy expended in postural changes was measured. An open-circuit mask technique was used to collect air expired by the animal. The small volume of the mask made possible immediate detection of changes in gas con- centrations due to postural changes. The 02, C02, and CH 4 concentrations in ex- pired air were monitored continuously during the periods by electronic gas an- alyzers, and recorded by a multi-channel recorder, along with rate of air flow through the mask and body position. These data then were ~eparated so that the energy expended while standing, lying, and during position change could be calculated. Results of this experiment did not sup- port the fa.(~tors presently being used to correct for activity during heat production measurements. A new method of correcting for activity was proposed; activity is cor- rected to a defined standard day. For each double change in body position dif- ferent frmn the number prescribed in a standard day a factor ± .195 kcal/kg W "7~ is added to the total heat production. The mean cmTection factor for excessive time spent standing or lying was 13.5% of the mean hourly heat production but varied with the length of time to be corrected.

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