NASHVILLE, Tenn. -- Bovine respiratory disease complex (BRDC) is the most significantly infectious disease in cattle, and is exacerbated by stress.
Chris Chase, DVM, PhD, South Dakota State University, says the multifactorial nature of BRDC — which includes viruses, bacteria, environment and immune competency of the the animal — can be worsened by stress.
At the National Cattlemen’s Beef Association Cattlemen’s College Feb. 1, Chase spoke about the role of stress on the immune system and how it can influence BRDC.
“Stress is a huge component of BRDC,” Chase said. “Stress is anything that reduces the immune response’s adaptation to intensive production.”
Stress pre-feedlot arrival includes weaning, salebarns, commingling, transportation, dehydration, time off feed and injury. Stress on cattle at the feedyard includes transportation, commingling, dehydration, lack of feed, new feed types, pen density, injury, exposure to new pathogens, competition, weather, handling, processing and more.
Chase said stress hormones produced by animals can make bacteria grow better.
“The more we can do to reduce stress, the less we’ll have the interaction with bacteria," he said. "Stress will decrease chemotaxis. Immune system cells have to be able to move to the infection site from the immune system. When you put animals on a truck for 700 miles these cells don’t move at all.”
Chase added that it takes 10 days to two weeks for the immune system cells to recover after these stressful events such as transportation.
“Stress affects neutrophil motility and phagocytosis,” he said.