Program for the control of subclinical mastitis in dairy Chios breed ewes during lactation

The present study was carried out to test the effectiveness of a standard treatment for the control of subclinical mastitis during lactating period in a modern, commercial dairy sheep farm. For this purpose, 140 Chios ewes were randomly selected and divided into two groups (control n = 70, treated n = 70) throughout their first lactating period. Milk yields were individually recorded and representative milk samples were collected from each mammary half, once monthly. Ewes giving apparently normal milk, but with Somatic Cell Counts (SCC) ≥ 500 × 103 cells/ml and bacteriologically positive were considered to have subclinical mastitis. Animals from the treated group suffering subclinical mastitis were subjected to a 3-day im treatment with Penethamate hydroiodide, while those of control group received no treatment. The percentage of animals from the treated group with SCC ≥ 500 × 103 cells/ml was lower compared to that of the control group throughout lactation, except from the last month when it was similar. Nevertheless, this difference was not significant (P > 0.05). Prevalence of subclinical mastitis was unaffected, although treated animals showed lower rates throughout lactation (P > 0.05). At the end of lactation 5.3% of the animals from the treated group and 15.6% from the control group had subclinical mastitis. Coagulase negative staphylococci were the only organisms isolated and they were generally sensitive to Penethamate hydroiodide. The predominant species identified was Staphylococcus epidermidis (60%). Ewes from the treated group produced more milk compared to those from the control group (P < 0.05).