Randomized clinical trial of ScourGuard® vaccine in dairy cows on colostrum brix score and transfer of passive immunity success in their calves

The use of a brix refractometer on dairy farms for colostrum management is becoming more common. This cow-side test can indirectly assess colostrum immunological quality and provide inputs to make decisions regarding colostrum feeding to calves. Achieving a high prevalence of transfer of passive immunity (TPI) success depends on factors such as colostrum immunological quality, volume of colostrum ingested, time delay between birth and ingestion of first colostrum meal, and level of bacterial contamination in colostrum. ScourGuard® vaccine (Zoetis, Kirkland, QC, Canada) is labelled in Canada for dairy cows as an aid for preventing calf diarrhea but it remains unclear if vaccinating the cows would yield greater colostrum brix score. Therefore, the first objective of the study was to quantify the efficacy of ScourGuard® vaccine in dairy cows for increasing colostrum brix score. The second objective was to quantify its efficacy for increasing TPI success in calves.