Prevalence and effects of management practices around calving on the health, behaviour, and productivity of Holstein dairy calves
This thesis is an investigation of the prevalence and impacts of different management practices around calving, with a specific focus on the effects of early systematic obstetrical assistance and the addition of gut-active carbohydrate to colostrum replacer, on Holstein dairy calves. The first study examined the analysis of a survey conducted on 236 Canadian dairy farms to gather information about the management practices currently used around calving on farms representative of the Canadian industry. A key finding was that 27% of the producers surveyed assisted all of their cows at calving. The second study was a randomized clinical trial conducted on a large commercial dairy farm in western Wisconsin, USA, to evaluate the effects of systematic obstetrical assistance provided early during the second stage of calving. The impacts of this practice were evaluated during the perinatal period in all calves, and until weaning for heifer calves. The main findings of this study were that the vigor scores of calves born from early-assisted calvings were better than those from calves born from unassisted calvings, and there were no significant negative impacts on the calves when their dams were assisted early during the second stage of calving. A second randomized clinical trial was conducted on the same large commercial dairy farm in Wisconsin to evaluate the effects of adding gut-active carbohydrates to colostrum replacer on dairy calves’ passive immunity absorption, health, and growth. The key findings of this study were that immunoglobulin absorption was not improved by the addition of gut-active carbohydrates to the colostrum replacer, and no significant effects were found on health or growth of the heifers to weaning. The findings described in this dissertation provide new information on the prevalence and effects of specific calving management practices and post-calving colostrum management on the health and behaviour of calves, and highlight areas for future study and enhanced knowledge translation and transfer concerning the management of dams and their calves during the perinatal period.