Subclinical mastitis in dairy sheep in Uruguay

In the countries of southern Latin America, sheep breeding is mainly oriented to meat and wool production. Sheep milk industry is a new production alternative for small farmers in Uruguay. According to recent publications, there are 25 million sheep in Uruguay, of which 72% are Corriedale. This breed represents 67.6% of the milking sheep. The objectives of this research were to determine the incidence, etiology and various epidemiological aspects related to subclinical mastitis in these animals. Throughout 3 years, during the milking period that extends from August to January, 500 sheep belonging to dairy farms and to an Agricultural Research Station were studied. The Californian Mastitis Test (CMT) was performed monthly on every milking sheep (5000 CMT in these 3 years). Milk samples were collected from all the positive glands and from 10% of the negative ones for bacteriological studies. An incidence of 7.5-8% of subclinical mastitis was subsequently found. The microorganisms isolated were mainly Staphylococcus aureus (46%) and coagulase negative Staphylococcus (18%). Concurrently, a correlation between the number of lactation and the development of subclinical mastitis was studied as well as the association between the presence of subclinical mastitis and the reduction of milk yield.