CATTLE USE OF MICROCLIMATES ON A NORTHERN LATITUDE WINTER RANGE

Grazing native range can help lower costs of wintering livestock. Howe ver, extreme cold and wind can negatively affect an animal's thermal b alance, increasing energy demand when the nutritive value of the forag e is low. Free-ranging cattle (Bos taurus) may exploit differences in topography and microclimate to minimize Or avoid environmental stresso rs such as high winds and cold temperatures. Cattle selection of micro climates in response to cold stress was studied over a 6-wk period for two consecutive winters. The objective of this study was to determine if cows respond to extreme wind and cold by selecting moderate microc limates for foraging. Cattle selected moderate microclimates for grazi ng and resting to avoid high winds and cold temperatures. They also te nded to remain in microclimates above their lower critical temperature (LCT) of-23 degrees C, even though reference climate conditions often were below their LCT. The availability of moderate microclimates in a pasture may allow cows to continue graz ing, thus maintaining intake, even when general conditions might otherwise cause them to defer from grazing.