Prevalence and etiology of subclinical mastitis in Awassi dairy ewes in southern Turkey

Abstract

In order to study the prevalence and etiology of subclinical mastitis a bacteriological survey on 16 Awassi dairy sheep flocks in southern Turkey was conducted. A total of 1458 milk samples from 729 Awassi ewes in mid-lactation were tested with the California mastitis test (CMT). Samples from 170 (11.7%) glands and 135 (18.5%) sheep had positive CMT results. Bacteria were isolated from 93 (6.4%) udder halves and 82 (11.2%) ewes. Positive CMT and bacteriological results were combined to define subclinical mastitis. The prevalence of subclinical mastitis and positive CMT samples among the different flocks ranged from 1.9% to 11.5% and 2.8% to 21.9% of the glands, and 3.8% to 19% and 5.7% to 31.3% of the ewes, respectively, with averages of 6.4% and 11.7% of the glands, and 11.2% and 18.5% of the ewes, respectively. Coagulase-negative staphylococci (CNS) were the most prevalent bacteria, representing 76.5% of the isolates. Staphylococcus epidermidis (35.7%) was the most prevalent species, followed by Staphylococcus xylosus (10.2%), Staphylococcus saprophyticus (10.2%), Staphylococcus warneri (9.2%), and Staphylococcus intermedius (7.1%). Antimicrobial susceptibility of 78 Staphylococcus isolates was evaluated in this study. The most effective antibiotics were cephalothin (97.4%), sulfamethoxazole-trimethoprim (97.4%), amoxicillin + clavulanic acid (97.4%), enrofloxacin (94.9%), gentamycin (92.3%), and erythromycin (84.6%). The relationship between CMT +1 score and the Staphylococcus spp. isolation rate was statistically significant (P < 0.001). It was concluded that subclinical mastitis is not highly prevalent and it does not pose a significant health problem for milking Awassi sheep flocks in southern Turkey.