THE EFFECTS OF ENZOOTIC BOVINE LEUKOSIS O N THE ECONOMICS OF CATTLE PRODUCTION IN COSTA-RICA

A herd of Jersey cows, located in Cartago, Costa Rica, was studied to determine the effect of enzootic bovine leukosis (EBL) infection on pr oduction, reproduction and mastitis. The prevalence and incidence of i nfection of EBL were for the period 1986 to 1992. Preventive and contr ol measures, investigated by the herd owner, reduced the incidence of disease in the herd during this period. No associations between the oc currence of bovine leukosis and variables representative of production and reproduction were found. The prevalence of mastitis in cows, with and without leukosis, was similar. It was concluded that infection wi th bovine leukosis virus did not have any adverse effects on productio n, reproduction or the incidence of mastitis in animals with no clinic al signs of EBL.