Redbo, I., Ehrlemark, A. and Redbo-Torstensson, P. 2001. Behavioural responses to climatic demands of dairy heifers housed outdoors. Can. J. Anim. Sci. 81: 9-15. The aim of the present study was to investigate the behavioural responses to different climatic demands of growing dairy heifers, during winter at a latitude of 60°N. Two groups (n = 11, 12) of yearling dairy heifers were housed in two similar 3-ha enclosures, characterised by deciduous forest, ley and pasture. Each enclosure also contained a lying area, a heated water source and a feed bunk from which the heifers had free access to grass silage. The behaviour and location of each heifer were recorded by instant interval observations every 5 min between 0600 h and 2000 h during 23 observation days spread over the entire winter period. Outdoor temperature, wind speed and solar radiation were measured continuously. The climatic energy demand (CED, W m -2 ) was measured with a heated animal model. The climate had significant effects on all the main activities and on the location of the heifers. Higher CED values corresponded to a greater number of observations of heifers in the lying area, and a greater incidence of lying and of ruminating, but to a decreased incidence of eating and grazing. Increased migration to the forested areas instead of to open areas reflected increasing CED values. The results from the present study show that dairy heifers adapt their behavioural activity and choice of location to the climatic conditions, to reduce energy expenditure. Thus, dairy heifers can be sustained in a cold climate if they are provided with wind breaks and dry lying places.

Keeping cattle inside on concrete slatted floors can be detrimental to their health and behaviour and is also costly. Therefore, 22 steers of the Swedish Red and White Dairy breed were used to investigate the effect of wintering outdoors on growing cattle. The steers had a mean weight of 310 kg at the onset of the study. During winter, 11 ‘indoor’ steers were housed in pens with concrete slatted floors and 11 ‘outdoor’ steers were kept in a field with access to a shelter and trees. From the end of April until slaughter in September, both groups grazed together. During winter, all steers were given clover silage ad libitum. They were weighed every month. The behaviour of the outdoor steers was recorded from November to the end of March. Outdoor temperature, wind speed and solar radiation were measured continuously. A heated model was used in order to calculate the climatic energy demand. The steers were never observed to shiver. They were not observed to use the shelter during daytime. The most frequently observed behaviour was ‘eating’, followed by ‘standing’. The lower the temperature, the more time the steers were observed lying down (P < 0·01). ‘Moving’ increased with increasing temperature (P < 0·05) as well as with increasing wind speed (P < 0·01). During the grazing period following the experiment, the former outdoor steers grew significantly (P < 0·05) better than the former indoor steers. However, there was no significant difference in overall growth rate from start to slaughter. This study suggests that the winter climate in this part of Sweden (latitude 60°N) did not affect in a negative way the welfare or the growth rate of steers kept outdoors.

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