Abstract
There is increasing interest from cattle lot-feeders in the use of shade to mitigate the effects of a potential heat-stress event, though it is unclear whether the reported benefits of shade in previous studies conducted in more high-risk heat-stress zones are pertinent in cooler temperate zones. The objectives of this study were to measure the welfare and performance benefits of shade provision for lot-fed cattle at a commercial feedlot located in a mild heat-stress risk zone in Western Australia. Six blocks of black Angus (Bos taurus) steers were inducted into the feedlot over 6 time windows across a southern hemisphere summer, with 80 cattle per block housed in a partially shaded pen (providing 3.125 m2 of shade per animal) and 80 in an unshaded pen. Parameters assessed in 960 cattle over the first 70 d in the feedlot included weight gain, feed intake, and physiological and behavioral indices of overall health and welfare. Over the months of October to May in which the experiment was conducted, shaded cattle demonstrated a modest 0.13 kg overall increase in average daily gain across the 70-d feedlot period (P = 0.13). There was no difference in dry matter intake between any block or treatment. The physiological and behavioral markers of health and welfare revealed that, even during to the hottest times of the experiment, the cattle were quite able to thermoregulate, via increased panting and seeking shade (if available), to maintain physiological homeostasis. In addition, we measured the effect of heat stress and shade provision on the affective state of the cattle. Qualitative behavioral assessment was used to indicate that the cattle in the "no stress" temperature humidity index (THI) category and the shaded cattle in the "moderate stress" THI category displayed the most positive demeanor (P < 0.05), being described as more "settled and sociable", while the unshaded cattle in the "moderate stress" THI category and all cattle in the "severe stress" THI category were described as more "agitated/anxious" (P < 0.05). Overall, the findings from the present study suggest that there are definite welfare and modest performance benefits associated with providing cattle with shade in summer in a feedlot situated in a temperate climatic zone.