1. VARIATION IN IMMUNE RESPONSE BETWEEN CANADIAN PUREBRED HOLSTEIN & NORWEGIAN RED CROSSBRED CALVES & FIRST CALF HEIFERS March 12, 2010 Shannon Cartwright Norwegian Red X Holstein (NRFX)Holstein (HO)

2. AntigenResponsePathogen type Examples of disease Type 2Antibody- mediated immune response ExtracellularMastitis caused by Staph aureus Type 1Cell- mediated immune response IntracellularBacterium that causes Johnes disease

3. Heifer Immunization Protocol Day 0 Day 7 Day 9 (6-9 Days post calving) Day 14 Day 14 -collect blood -collect blood -final skin-fold -collect blood -collect blood -final skin-fold -immunize -skin-fold measurements measurements -immunize -skin-fold measurements measurements type 1 & 2 antigens -intra-dermal injections -immunize human serum albumen (HSA) -collect blood 1° for HSA 1° for HSA 3° DTH

4. Evaluation of AMIR Sera obtained from blood samples taken on days 0, 14 and 21 for calves and days 0, 7 and 14 for heifers Antibody activity to test antigens is determined by ELISA (Begley et al. 2009)

5. ControlTest

6. Summary Calf Results Crossbreds had significantly greater primary IgG and IgM antibody response Significant farm*breed interaction for secondary IgG antibody response - on farm where effect of breed significant crossbreds had greater antibody response No difference in DTH response between breeds Results indicate crossbred calves may have enhanced defence against extracellular pathogens

7. Conclusion Crossbred calves significantly greater AMIR therefore enhanced defence against extracellular pathogens Crossbred heifers significantly greater AMIR & CMIR therefore enhanced defence against extracellular & intracellular pathogens during peripartum period