Dam Age Differentially Affects Immune Response of Her Calf to Bovine Respiratory Disease Vaccination

Understanding the biological factors that affect immunological responses may be beneficial in developing more effective bovine respiratory disease vaccination strategies. Dam traits, such as age and vaccination history, are not considered when developing vaccination protocols or assessing vaccination efficacy, even though both factors may influence the transference of passive immunity; therefore, a preliminary study was conducted to determine the effect of dam age on the immune response of their calves to vaccinations. Calves born to dams of various ages were vaccinated with a modified live vaccine at 3 to 4 months old, revaccinated with either the same modified live or an inactivated vaccine at weaning, and boosted with the same vaccine 28 days later. Immune and cortisol measures were taken upon initial vaccination, revaccination at weaning, and then 14 and 28 days post-revaccination and post-booster. Overall, calves from older-aged dams began to exhibit a pattern indicative of a dampened immunoglobulin-G response to revaccination and booster, regardless of vaccination type. In contrast, calves from the youngest and oldest dams who received one modified live and two inactivated vaccines had the highest serum-neutralizing titers for most antigens present in the vaccines. These preliminary data partly imply that it may be plausible that the more doses of modified live vaccines the dam receives, which increase with each pregnancy, may affect the immune response of her progeny to vaccination at weaning and revaccination. This may be due to the effects on maternal passive immunity and is further affected by the type of vaccination her progeny received for some measures. However, more research is necessary to elucidate further the effects biological factors have on the immune response to vaccination, develop better vaccination strategies, and further validate these findings through increased sample sizes.