Energy expenditure and respiratory activity of sheep during feeding

Abstract

Energy costs of feeding and respiratory changes during the ingestion of prepared rations were measured in experiments on penned sheep.

Feeding energy increments per kilogram liveweight (increased energy expenditure attributable to the act of eating) ranged from 5.3 to 12.4 cal/min. Differences between sheep and between rations were not significant.

Energy costs of eating (increased energy expenditure per gram of ration ingested) varied with the type of ration. A concentrate ration was ingested at an energy cost (per kg liveweight) of 0.3–0.6 cal/g ration, whereas chaff rations cost 1.2–1.9 cal/g ration.

A marked reduction in respiratory frequencies and respiratory minute ventilations occurred during feeding whenever the pre-feeding respiratory activity was elevated due to the ambient temperature. When the respiration was eupnoeic before feeding there was a slight increase with feeding. While sheep were eating, respiratory frequencies ranged between 20 and 40 per minute and respiratory minute ventilations from 4.5 to 8.4 litres.