Invasive Species Compendium

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Abstract

Epidemiological studies of clinical and subclinical ovine mastitis in Awassi sheep in Northern Jordan.

Abstract

A cross-sectional study of 46 Awassi flocks, selected by stratified random sampling, investigated the prevalence of intramammary infections, to assess the effect of flock size and parity on somatic cell count (SCC) and to identify major udder pathogens. Of the 3472 udder halves examined, 29.8% had SCC >106/ml and 0.03% had dry teats due to chronic mastitis. Flocks with 30-49 milking ewes (small flocks) were much younger than flocks with 50-99 ewes (medium) and flocks with ≥100 ewes (large). Paired analyses of both halves of the udders identified significant mean differences for small and large flock size, and for medium and large flock size. Mean lnSCC was lower in samples obtained from the left half compared with samples from the right half of the udder. Multiparous ewes had higher mean lnSCC than primiparous ewes. Ewes with twin lambs had higher mean lnSCC in the right half of the udder compared with single-lamb ewes. Samples collected in January (winter) had lower mean lnSCC compared with samples collected in June. The commonest isolates from subclinical mastitis cases were coagulase-negative staphylococci (17.8%), E. coli (13.6%), Streptococcus agalactiae (6.8%) and Staphylococcus aureus (6.8%). Of the 46 flocks, 20 were monitored monthly for 9 consecutive months to determine the incidence of clinical mastitis diagnosed by shepherds or/and sheep farmers with major pathogens. The incidence of clinical mastitis (number of clinical cases per 100 ewe-months) were 2.1±1.9, 1.9±1.1 and 1.2±2.1 for small, medium and large flocks, respectively. The overall population estimate was 1.7±0.02 cases/100 ewe-months. The commonest clinical isolates were S. aureus (22% of all clinical isolates) and E. coli (14.2%).