In the first phase of the experiment, between July and November 2009, around two thousand three hundred thermal images of cattle hooves were taken. During these experiments, ambient temperatures ranged from 10°C to 24.8°C and general weather conditions from a warm summer's day through to cold and damp winter conditions. Hoof temperatures measured by IRT ranged from approximately 10°C to 36°C (Figure 2a ) and depended markedly on ambient temperature (Figures 2d &3) . Furthermore, the variability in hoof temperatures was greatest at lower ambient temperatures (Figure 2d ). The median range in hoof temperatures for individual animals on a given day was approximately 6°C, but in some cases it was > 12°C (Figure 3 ). This range often reflected one hoof or side being markedly warmer than the other (for example, animals 362, 762, 766 and 769), but sometimes there was no clear explanation for the difference (for example, animals 763 and 777).