Understanding The Effects Of Stress

Animals can suffer stress even during ‘normal’ handling, making them more susceptible to disease.

Stress is defined as an external influence on the balance (homeostasis) of a system, which has the potential to trigger a negative reaction.

Homeostasis maintains the stability of the body’s internal environment in response to changes in external conditions. On a very hot day, for example, an animal seeks to maintain stability by keeping in the shade, drinking more water and eating less. The scientific name for this is ‘thermoregulation’; if successful, the animal will suffer no stress.

Thermoregulation is easier during hot spells than cold spells, which is one reason why more stress-related diseases are encountered during the change from autumn to winter.

Recent research shows that even routine handling can cause stress in cattle.

When animals (including humans) are stressed, the steroid hormone cortisol is released. It supplies energy in the form of glucose and enables the animal to escape from the stressor. In this respect, it benefits the animal, but the release of cortisol can also have major negative consequences.

In livestock, too much cortisol due to constant stress can hamper successful reproduction and increase susceptibility to disease due to compromised immunity.