Review

Abstract

Pre-weaning calf health continues to be an important factor in the profitability of beef-cattle operations. Dystocia, diarrhea and pneumonia are the most common syndromes reported as contributing to calfhood disease. Risk factors for preweaning morbidity and mortality include age of dam, environmental temperature at birth, period of birth-time within the calving season, and cow/calf population density. Because calves are born agammaglobunemic, passive transfer provided by colostrum consumption continues to be important. Total immunoglobulin absorption is controlled by colostrum lgG concentration, the amount consumed, and the amount of time elapsing from birth to ingestion. Neonatal diarrhea and calf pneumonia can occur at different calf ages, with pneumonia occurring over a longer calf-age range; therefore, management for pneumonia must concentrate on the entire birth-to-weaning time period. A challenge in stimulating immunity to respiratory pathogens is selecting the appropriate vaccine at the most likely time to generate a protective response. Stimulation of active immunity in calves is somewhat dependent on colostrum quality and quantity consumed, the pathogen protected against, and the time period when maternal antibodies decrease to non-interference levels may be unique for each calf. Neutralizing antibody measures suggest that calves vaccinated in the presence of high maternal antibodies do not mount an immune response. However, some studies suggest vaccination, in the presence of maternal antibodies, results in a response not measurable by neutralizing antibodies, but nonetheless protective against clinical illness. The objective of this paper is to describe risk factors and control measures for pre-weaning diseases specifically focused on pneumonia.