FREQUENCY OF SUBCLINICAL MASTITIS AND OBSERVATIONS ON SOMATIC-CELL COUNTS IN EWES MILK IN NORTHERN GREECE

Somatic cell counting by the Coulter Counter method, California mastit is test and bacteriological examination were performed on milk samples taken at fortnightly intervals throughout lactation from healthy prim iparous and multiparous ewes of Chios and Karagouniki breeds and from healthy ewes in five grazing flocks in northern Greece. The proportion of the bacteriologically positive milk samples was 0.22. The prevalen ce of subclinical mastitis ranged, between the flocks, from 29 to 43% of the ewes. Subclinical mastitis occurred more frequently in Karagoun iki than in Chios ewes and in multiparous than in primiparous ewes of both breeds. Coagulase-negative staphylococci and S. aureus were isola ted in 44 and 33% of the bacteriologically positive samples, respectiv ely. No parity, breed or flock differences in normal somatic cell coun t were noticed, but stage of lactation influenced normal somatic cell count both in primiparaous and multiparous ewes. The results of this i nvestigation also suggest that (a) ovine milk samples with somatic cel l count more 1000 X 10(3) cells per ml, should be tested bacteriologic ally, (b) somatic cell count values between 1000 and 2000 X 10(3) cell s per ml should cause suspicion about the presence of coagulase-negati ve staphylococci in the milk, and (c) the presence of S. aureus in ewe 's milk results in a significant increase in somatic cell count, but t he wide range of the values does not permit us to suggest any threshol d value. The significant correlation between the results of the Coulte r Counter somatic cell count method and the California mastitis test, indicates that the latter can be used for the determination of somatic cell count in ewe's milk.