[Health and fertility in relation to production. Climate and health in young farm animals].

In animals, the climatic factor of environmental temperature causes specific physiological adaptations dependant on the nature and duration of the 'stressor'. The absolute temperature appears to be of less importance in influencing animal health than the extent of deviation from the thermoneutral zone. The difficulty experienced by animals in maintaining thermoregulation affects the immunological response and possibly also resistance. In the literature, the duration and type of changes involved are not always clearly stated. This may explain why the reactions to cold and warmth are not always identical. Also, the reactions which partly influence resistance are sometimes not compatible with climatic stress. Further research is needed for improved understanding of the relationship between the resistance of the animal and the duration and extent of climatic stress.