ABSTRACT
The shelter aspect of environmental management has been applied for a long time. Shepherds kept their flocks in folds at night thousands of years ago. An animal is under stress when it is required to make extreme functional, structural, or behavioral adjustments in order to cope with adverse aspects of its environment. An environmental factor that contributes to the stressful nature of an environment is called a stressor. Scientists in a wide range of disciplines have been "measuring stress in animals" with increasing frequency over the past century and a half. External environment comprises all of the thousands of physical, chemical, and biological factors that surround an animal's body. The homeokinetic animal attempts to control all aspects of its internal environment via adaptive responses similar in principle to a house's temperature-control system. A strain is any functional, structural, or behavioral reaction to an environmental stimulus. A new study of stress effects on tumor rejection demonstrated psycological components of stress responses.
