Abstract

Behavioural responses were investigated in individually fed (maintenance to twice maintenance) feedlot steers housed inside (5 to 27°C) or outside (−40 to 19°C) from October to March (Experiment 1), and in steers exposed to temperatures of −20, 0 and 20°C in controlled temperature chambers in September and again in December (Experiment 2). Respiratory frequencies of the outside steers increased with increases in feeding level ( P<0.05) and temperature ( P<0.01). Steers in the outside lot increased the time spent ruminating as temperature decreased ( P<0.01). As the winter progressed the maximum temperature at which shivering was observed decreased from −9°C in November to −25°C in January, and shivering was not observed at −30°C in March. The outside feedlot steers increased the time spent lying down ( P<0.05) but decreased wet grooming (licking) behaviour ( P<0.05) as temperature decreased. Rumination activity by the steers in Experiment 2, while in temperature controlled chambers, was increased by exposure to −20°C ( P<0.01). The frequency of reticular contractions was greatest during periods of rumination ( P<0.01) and was inversely related to exposure temperature. The intensity of shivering was more severe in September than in December. Respiratory frequencies of steers in Experiment 2 increased with exposure temperature ( P<0.01). However, the increase with temperature was more pronounced in the December than in the September series of exposures ( P<0.05).

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