EFFECTS OF SEVERE WINTER CONDITIONS ON PERFORMANCE OF FEEDLOT STEERS

Abstract

An analysis of 7 yr of monthly records on a total of 1,970 steers from the University of Saskatchewan feedlot at Saskatoon was conducted to determine the effects of climate on steer performance. During the months of December, January and February (mean monthly temperature −17 C), average daily gain fell to 70% of the average recorded over the remainder of the year. Production efficiency was also severely affected. The feed required per unit of gain and the metabolizable energy intake per unit of gain during winter were, respectively, 149 and 140% of the mean requirements from March to November. These effects were not caused by differences in weight, maturity or energy intake of the steers. Animal performance appeared to be related to climatic factors over the entire annual range. Average daily gain and feed per unit gain were significantly correlated with mean ambient temperatures (r = 0.74 and −0.85, respectively), days below −23 C (r = −0.74 and 0.86), windchill (r = −0.73 and 0.82) and dewpoint (r = 0.74 and −0.83). Voluntary feed intake was markedly lower in winter than during the onset of colder weather in the fall. Cattle fed in the 90 coldest days required an extra 220 kg feed to reach market weight. Winter climatic conditions, therefore, have a marked adverse effect on full-fed feedlot cattle in Western Canada, even when the animals are well bedded and sheltered from wind.