| [serological prevalence and evaluation of the risk factors of bovine enzootic leukosis in the bogotá savannah and the ubaté and chiquinquirá valleys, colombia]. | the authors present the results of a study to determine the serological prevalence of the enzootic bovine leukosis virus among dairy cows in the sabana de bogotá region and the ubaté and chiquinquirá valleys, the principal dairying areas of colombia. samples were taken from 919 animals selected at random from 420 farms in 51 municipalities, in accordance with a statistical sampling procedure developed previously, based on the cattle census maintained by the animal health and disease control offi ... | 1998 | 9850543 |