Associations between immune competence, stress responsiveness, and production in Holstein-Friesian and Holstein-Friesian × Jersey heifers reared in a pasture-based production system in Australia

摘要

The objectives of this study were to assess antibodyand cellular immune responses in first-lactation dairyheifers reared under a pasture-based production systemand to investigate associations between immunecompetence and stress responsiveness, health, andproductivity. A commercial vaccine was used to induceantibody and cellular immune responses and, based onmeasured responses, animals were classified as aboveaverage, average, and below average for each trait independentlyand in combination (overall immune competence).Overall immune competence phenotypic rankingswere generated by combining standardized residualvalues for antibody and cellular responses measuredin individual heifers. Cortisol responses to handlingand yarding were used to assess stress responsiveness,worm egg counts were used to assess internal parasiteburden, somatic cell counts to assess udder health andestimates of total daily milk volume, and milk fat andmilk protein contents to assess productivity. A totalof 393 Holstein-Friesian and Holstein-Friesian × Jerseycrossbred heifers from 2 herds practicing seasonal calvingin a pasture-fed production system were enrolledin the study. The immune competence phenotypes ofindividual heifers were assessed before their first matingand their subsequent performance during their firstlactation was monitored. Animals with below-averageantibody and cellular immune competence had higherserum cortisol concentrations compared with theircounterparts following handling, suggesting they hada reduced ability to cope with management-inducedstress. Furthermore, a significant negative (favorable)correlation was observed between antibody responsesand stress responsiveness. Similarly, correlations betweenantibody responses and internal parasite burdenwere significant and negative (favorable). No correlationswere observed between overall immune competenceand milk yield, milk fat, and milk protein content.