The Effect of Climate Parameters on Sheep Preferences for Outdoors or Indoors at Low Ambient Temperatures

SIMPLE SUMMARY: Sheep may be kept indoors over the winter period, especially in cool climates. There is currently a drive to keep sheep outside, especially on organic sheep farms. This paper examines the preferences that sheep have in cool conditions for outdoor or indoor housing to inform management practices. We found no evidence that mature sheep should be kept confined indoors throughout the winter period, even in normal winter weather conditions in northern Europe, with temperatures as low as −20 °C and where precipitation and relative humidity may be high. In all conditions, during this trial, the majority of ewes preferred to be outside. Access to the outdoor area should be managed to restrict outdoor access for lambs, ewes with unweaned lambs and recently shorn sheep. Conditions in which sheep did choose to move indoors were: low wind chill values (≤10 °C) and/or high air humidity (>90%). In such cases, sheep should have the opportunity to shelter indoors. ABSTRACT: Threshold temperatures for cold stress in sheep are not well understood, the available literature is somewhat dated and reports relate to winter temperatures that are relatively benign. Sheep’s preferences for outdoor versus indoor environments, when given free access to both, were investigated in the winter period at temperatures as low as −23 °C. Two sheep farms, one with access to a permanent uninsulated barn and one with a polytunnel shelter, both with free access to an outdoor area, were used. Observations were made with a camera positioned to register numbers of sheep outdoors and indoors, with one image taken hourly over twenty-four hours. The sheep clearly preferred to be outdoors; on all occasions the majority of the sheep were outdoors. There was, however, a significant decrease, albeit small, in the numbers of sheep choosing to be outdoors at lower temperatures (p < 0.001), higher relative humidity (p < 0.001) and greater wind chill (p < 0.001). Therefore, even at cooler temperatures than reported previously, sheep are motivated to be outdoors rather than indoors. It is not implicitly good for their welfare, and may not be true for lambs and shorn sheep, but accessing an outdoor area appears to be what they choose to do when given the choice.