Estado inmunológico de terneras y terneros de lechería en la Región Huetar Norte de Costa Rica.: A？o I

the objective of this study was to characterize the immune status of dairy calves in the northern plains of costa rica. 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 2.8 to 11.0, with an overall mean of 6.2 g/dl. of all the animals evaluated, 31.8% had failure of passive transfer. when considering sex of the calves, 31.4% of females and 25.3% of males failed to obtain adequate levels of immunity and concentration of tsp showed significant differences (6.2 vs. 5.9 g/dl, respectively). calves born to holstein x jersey crosses had significant higher tsp concentrations than calves born to holstein dams. when considering calving of the dam, offsprings born to first time heifers tsp concentrations of 6.3 g/dl and showed the lowest percentage of animals with inadequate transfer of immunity. tsp showed no significant differences for method of colostrum feeding; however, calves that suckled colostrum showed a higher proportion of animals with inadequate passive transfer when compared to calves that received colostrum by bottle (34.1 vs. 29.3%). colostrum management practices should be placed in order to minimize the risk of failure of passive transfer in dairy herds in the northern plains of costa rica.