Browsing by Author "Silas, Haley"

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    Impact of Age and Duration of Maternal Separation on Processing Stress and Vaccine Responses in Pre-weaned Beef Calves
    (2022-06) Silas, Haley; Pajor, Edmond; Windeyer, Claire; Galezowski, Angelica; Janzen, Eugene
    Spring processing is a common practice in western Canadian cow-calf herds that involves separating calves from their dams and restraining the calves while they receive a combination of procedures that may include vaccination, castration, branding, and dehorning. Spring processing events are thought to be stressful for the calf; however, the impact of their age and the duration of maternal separation is not known. The first study (Chapter 2) assessed impacts of age and duration of maternal separation on stress experienced by calves at processing. It was found that four- and eight-week old calves had similar behavioural indicators of stress and cortisol concentrations after processing. Calves separated for five hours before processing were less active after processing than calves separated for one hour before processing. This decrease in activity in calves separated for longer could indicate they have become exhausted or acclimatized to their pen. The second study (Chapter 3) assessed the impact of age and stress on immunoglobulin G (IgG) and immunoglobulin M (IgM) antibody responses to intranasal vaccination with a modified live vaccine against bovine herpesvirus type 1 (BHV1), parainfluenza virus type 3 (PIV3), and bovine respiratory syncytial virus (BRSV; Inforce3®, Zoetis Inc., New Jersey, USA). In this study, BRSV, PIV3, and BHV1 IgG concentrations remained relatively similar from baseline to post-vaccination, while BRSV, PIV3, and BHV1 IgM concentrations increased during the same period. Furthermore, this increase was greater in eight-week old calves than four-week old calves, potentially because old calves were more responsive immunologically than the younger calves. Cortisol concentration proved to have minimal association with antibody concentrations after vaccination, with only some weak positive correlations between cortisol at certain timepoints and BRSV IgG or BHV1 IgG concentrations post-vaccination. Overall, there was no difference between vaccinated and unvaccinated calves, suggesting that maternally derived antibodies may have prevented a detectable humoral immune response to vaccination. To our knowledge, this study was the first to consider IgG and IgM immune responses to vaccination at industry-relevant processing ages.