Optimizing passive immunity in beef calves: An evaluation of colostrum management strategies and the impact of total and specific immunoglobulin G on health and growth
Date
2021-09-20
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Abstract
Inadequate transfer of immunoglobulins from dam to calf via colostrum continues to present a challenge on cow-calf operations. Therefore, the aim of this thesis was to investigate management strategies to optimize the transfer of passive immunity (TPI) in beef calves and to identify risk factors associated with and impacts of total and specific immunoglobulin G (IgG) concentrations. Chapter 2 demonstrated that Brix refractometry is a practical, accurate tool for on-farm assessment of IgG concentrations in beef cow colostrum and that thresholds of <24 and ≥30% Brix indicate low- and high-IgG colostrum, respectively. In Chapter 3, calves fed a moderate volume and IgG concentration (1.4L, 70g/L IgG) of colostrum product nursed their dams significantly sooner than calves fed a small (1L) or large volume (2L) with a high IgG concentration (100 g/L), as did calves fed by nipple bottle compared to those fed by oro-esophageal tube feeder. Calf serum IgG concentrations were similar among all interventions studied. Chapter 4 evaluated optical and digital serum total protein (STP) refractometers, and the Brix refractometer for on-farm assessment of serum IgG concentration in beef calves. All three refractometers demonstrated excellent test characteristics, and STP concentrations of ≤5.8 g/dL and Brix percentages of ≤8.7 % can be used to detect inadequate TPI (i.e., <24 g/L IgG). Lastly, in Chapter 5, colostrum intervention was the most consistent predictor of poor TPI, and dam parity was the most consistent predictor of pathogen-specific IgG concentrations. We identified poor producer compliance with vaccine label instructions and variable impacts of pre-calving vaccination on specific calf serum IgG concentrations. Calves with poor TPI were more likely to get treated and die and showed lower weight gains in the pre-weaning period, while higher bovine rotavirus-specific IgG concentrations were associated with lower pre-weaning mortality. Our findings suggest room for improvement regarding on-farm vaccination strategies, particularly in heifers, and the need for further improvement of colostrum management in beef calves. Overall, this thesis identified important risk factors associated with poor TPI, highlighted the negative effects it had on pre-weaning health and growth, and offers a first step towards the development of practical, beef calf-specific colostrum management guidelines.
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Keywords
transfer of passive immunity, immunoglobulin G, beef calves, specific maternal antibodies, calf health
Citation
Gamsjäger, L. (2021). Optimizing passive immunity in beef calves: An evaluation of colostrum management strategies and the impact of total and specific immunoglobulin G on health and growth (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.