Energy Expenditure by Heifers Grazing Crested Wheatgrass of Diminishing Availability

Abstract

The daily mean energy expenditure of free-ranging heifers grazing crested wheatgrass rangeland was estimated as 161 kcal/kgBW^.75/day using the carbon dioxide entry rate technique (CERT). This was 46% greater than the mean 110 kcal/kgBW^.75/day estimated for stall-fed heifers consuming similar forage. Under laboratory conditions, CERT can provide a mean estimate of energy expenditure that has a standard error of 5% and a coefficient of variation of 20%.