DIRECT EFFECTS OF COLD WEATHER ON THE ENERGETIC EFFICIENCY OF BEEF PRODUCTION IN DIFFERENT REGIONS OF CANADA

Abstract

Direct measurements of the energy exchanges of cattle in cold and windy environments were used to derive partial regression equations predicting the effects of air temperature and body weight on tissue insulation, and wind speed and coat depth on external insulation. These measurements were combined with estimates of thermoneutral heat production to predict still air critical temperatures for feeder steers, pregnant cows and growing calves. These values ranged from −31 to −38, −11 to −23, and −16 to −21 C in the three groups, respectively. Meteorological records from different sites in Canada showed that cold has a negligible effect on the energetic efficiency of sheltered feeder cattle. The effects of cold on pregnant cows and growing calves are significant but not excessive. Examples are presented of the extent to which wind, sunshine and precipitation may influence critical temperature and the results are discussed in terms of regional disparities within Canada in the costs of keeping beef cattle, the economics of environmental control and the recommendations with respect to beef production of the Canadian Federal Task Force on Agriculture.