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130. Care should be taken (e.g. by the provision of suitable shelter) to ensure that cattle are protected from extremes of weather. Significant problems are caused by heat stress, particularly with high yielding cows. The high summer temperatures in the early and mid 1990s had a marked effect on herd fertility. Pregnancy rates were severely affected, due to adverse effects on the quality of follicular development and high embryo loss.
131. High temperatures lead to an increase in deep-body heat. Appetite can be severely depressed and, as a result, excessive weight loss can occur, with losses of up to 100kg liveweight recorded. This has obvious welfare implications. Furthermore, cows show signs of discomfort and are seen to be panting in an attempt to lose heat. Although high ambient temperatures are common place in many parts of the world, little information about control of heat stress is available for UK conditions. Farmers would benefit from advice about effective provision of inexpensive and readily available shading (such as natural shade from trees and hedges) during the summer period or other means of reducing body heat in dairy cows.
132. Research is needed, under UK conditions, on methods of avoiding heat stress.
133. Government should produce and distribute advisory literature on the avoidance of heat stress in dairy cattle. This should form part of the "Action on Animal Welfare" series.