Evaluation of a combined vaccine against staphylococcal mastitis in ewes

The effectiveness of combined staphylococcal vaccine (CSV), prepared from Staphylococcus aureus and coagulase negative staphylococci (CNS: Staphylococcus epidermidis, S. simulans, S. saprophyticus), on staphylococcal mastitis in sheep was determined. The group of pregnant sheep was vaccinated subcutaneously into supramammary lymph node twice at 3 week interval. Similarly, sterile saline was administered to controls. Blood and milk samples were collected before and at days 21 and 51 after the vaccination. The titre of S. aureus and CNS antibodies in serum and whey was determined using a modified ELISA. Levels of staphylococcal antibodies in serum and whey of the vaccinated animals were significantly higher compared with the controls. Intramammary infection rate by S. aureus was lower in the CSV group (7.70%) compared with the controls (30.76%) While intramammary infection rate for CNS was 19.23% in the controls, no isolate was demonstrated in the CSV group. Therefore, the effectiveness of CSV was found to be useful to decrease intramammary infection rate of S. aureus and CNS in ewes.