The objective of this study was to determine the transfer of passive immunity in dairy heifer calves in Costa Rica. The data presented correspond to total serum protein (TSP) measurements obtained in the period between 2010 and 2013, between August and November in 50 dairy farms. A total of 2500 heifer calves were sampled. Dams breed were classified into Holstein, Jersey, Holstein.Jersey crosses and others. For the purpose of this study, failure of passive immunity was considered when TSP concentration was less than 5.5 g/dl. TSP concentration ranged from 2.0 to 10.0, with an overall mean of 5.9 g/dl. Of all the calves evaluated, 38.8% presented failure of passive transfer of immunity. Calves born to Jersey and Holstein×Jersey crosses had significantly higher TSP concentrations than calves born to Holstein and other breeds. When considering calving of the dam, there were no significant differences on TSP concentration; however, offsprings born to first lactation heifers showed the lowest percentage of animals with failure of passive transfer of immunity. There were significant differences on TSP concentrations (P<0,05) between calves that were allowed to suckle their dams and calves that were given colostrum by bottle. Failure of passive transfer of immunity was higher when calves stayed with their dams (44% vs. 33%).

Keywords: total serum protein, colostrum, immunoglobulins, dairy cattle.