Evaluation of digital Brix refractometry in assessing maternal colostrum quality and transfer of passive immunity in beef cattle

Abstract

Newborn calves depend on passive immunity acquired by the timely ingestion of colostrum containing adequate concentrations of immunoglobulin G (IgG). Failed transfer of passive immunity (FTP) in calves is defined as serum IgG concentrations <10 g/L, measured between 1 and 7 days after birth. It is estimated that up to 27% of beef calves suffer from FTP, which can affect calf health, survival, and growth. In contrast to dairy calves that are typically hand-fed prescribed volumes of colostrum, beef calves ideally suck from their dam and do not need human intervention. This requires the calf to be vigorous, the cow to allow the calf to suckle, and the colostrum to be of sufficient quality and quantity. However, beef producers rarely know the quality or quantity of colostrum available to, or consumed by, the calves in their care. Although measuring the volume of colostrum is not generally feasible for beef producers, there are on-farm tools available to estimate IgG concentration. Optical and digital refractometers are widely used to evaluate colostrum and serum of dairy cattle. However, there is minimal published research evaluating these tools in beef cattle. Objectives of this study were to evaluate the effectiveness of the Brix refractometer for estimating quality of maternal colostrum and levels of passive immunity acquired by commercial beef calves.