The Effects of Stress on the Immunology of the Stocker Calf

Abstract

Many stressors contributing to bronchopneumonia have been identified and reported. Of all these stressors, transportation seems to have the most detrimental effect on the animal. Serum cortisol concentrations are often used as a measure of stress. Trucking of calves resulted in a significant (P<.05) increase in cortisol levels while weaning produced only a small increase. Another effect of transportation stress is excessive shrink. Studies conducted at this laboratory indicate that cattle that are transported shrink more than cattle that are deprived of feed and water for the same amount of time. Trucking and stress in general also have profound effects not only on the total numbers and percentages of white blood cells, but on their functional capabilities as well.