From the dietetic point of view, it is not recommended to feed dairy cows (especially the high-producing ones) with frozen foodstuffs. However, during the winter period air temperatures are sometimes fluctuating deep below the freezing point. The objective of this study was to ascertain the maximum depth of frozen silage in silos and to describe the response of dairy cows to frosts and frozen feedstuffs. Temperatures were measured by a thermocamera P45. During the experimental period, the air temperatures were – 7.7 degr.C and – 21.4 degr.C, at 14.00 and 7.00, respectively. Although the dairy cows reacted to decreased temperatures of air and feed mixture by a decrease in daily milk production, this response was not marked too much. In the course of January, the records of milk production on very cold (i.e. frost) days were comparable with those recorded on days with milder days. The overall correlation was relatively low, i.e. only 0.35.