For young calves, such as dairy calves on a calf ranch, the stress of ongoing disease (enteric, respiratory or other) and suboptimal dietary energy, protein, fat-soluble vitamins or minerals are likely to be common causes of an impaired response to vaccination.

Stress is widely understood to have a negative effect on growth and disease resistance of calves, but research has shown different effects of acute or short-term stress versus chronic stress. Acute or short-term stress can actually improve immune responsiveness of animals because cortisol, epinephrine and norepinephrine, which are released during stress, can all improve many responses of the immune system in the hours after these hormones are released, says Amelia Woolums, DVM, MVSc, PhD, Dipl. ACVIM, Dipl. ACVM, University of Georgia.

“However, if increased levels of stress hormones are circulating for many days, immune responses can deteriorate,” Woolums adds. “Calves subjected to a brief period of stress (such as several hours) are likely to have a normal or perhaps even slightly improved response to vaccination, but calves that are subjected to stress for several days around the time of vaccination are likely to have a sub-optimal response.”

Chronic stress can be induced by a variety of factors including cold or heat stress, social stress associated with mixing of animals from different origins or age groups, frightening noise or other stimuli, inadequate food or water, or disease.

Read more about neonatal immunology here.