Climate, Summer Heat and Winter Chill

In North America, depending on where you live it could be warm, cold or bitterly cold. Adapting to local climatic conditions is but one of many factors a farmer must deal with on a daily basis. Near Vancouver, British Columbia, where I live we have experienced a rather mild winter so far with only a few days of below freezing temperatures. Eastern Canadians have had to cope with very cold temperatures and meters of snow. Farmers in southern regions (or the Southern Hemisphere) enjoy warm or even hot weather at this time of the year. With all these demands on our livestock, a farmer must constantly be aware and prepared in order to keep the animals healthy, productive and happy.

Animals can loose or gain heat by a variety of means. Conduction is the flow of heat from warm to cold objects. A cow standing in a deep snow is an example of conduction heat loss. Convection is the flow of heat from warm to cold areas through air or water. A windy winter day is good example of how convection heat loss occurs. A cool breeze on a summer day works also to cause the animal to loose heat but in this case, it benefits the animal. Evaporation is heat loss by the evaporation of moisture. During summer, the evaporation of sweat or respiratory tract moisture cools the animal. Radiation is the last method of heat transfer. It is between two objects that are not touching. Heat is transferred through radiant energy. This is why a bright sunny day winter feels warmer (radiant energy from the sun) and a bright sunny day in summer is feels hotter.

All animals have a comfort zone or temperature in which they are able to function at maximum potential. All farm mammals and birds are capable of maintain a stable body temperature. If however, the core body temperature falls or increases outside of its normal range the animal can become cold or heat stressed and in extreme cases die.

Animals that are in cool or cold temperatures try to maintain their constant body temperature by increasing food intake, seeking warmth/shelter, shivering or moving around which generates heat. In cases of environments warmer than comfortable, an animal will increase water intake, pant, sweat or seek shelter. Cold weather is an unpleasant fact for many regions of the world. Therefore, farmers must recognize the problems associated with livestock production in these areas and learn to adapt to these conditions. During cold, heat loss by conduction (flow of heat from warm to cold objects) and convection (flow of heat from warm to cold areas through air or water) increases. The use of shelter, windbreaks, supplemental heat sources, increased feed are some of the ways farms cope with cold temperatures. Some animals are able to tolerate the cold better than others are. For example: sheep have wool for insulation and cattle due to their coats and large volume relative to surface area. Pigs have no coat to speak of and birds due to their small size can be cold stressed.