INCIDENCE OF CLINICAL MASTITIS AND PREVALENCE OF SUBCLINICAL UDDER INFECTIONS IN JORDANIAN DAIRY-CATTLE

Nineteen Jordanian dairy farms selected by stratified random sample were monitored between July 1991 and August 1992 in order to: (a) determine the incidence of clinical mastitis; (b) assess the influence of season and herd size on the incidence of clinical mastitis; (c) estimate and identify major udder pathogens and their prevalence. Sixty-five percent of clinical mastitis cases occurred between December and April. The incidence of clinical mastitis was 6.8, 5.0 and 3.3 cases per 100 cow-months at risk for herds with 10-29 cows, 30-59 cows, and more than 59 cows, respectively. The most common organisms isolated from clinical cases were coagulase-negative staphylococci (16%) and Staphylococcus aureus (14%). The most prevalent bacterial pathogens in subclinical udder infections were coagulase-negative staphylococci (9.4-11.8%), Staphylococcus aureus (9.2-12.1%) and Corynehacterium bovls (5.8-7.5%). The prevalence rates of Escherichia coli and Enterobacter spp. increased during the winter season for the three herd-size strata.