Staphylococcal capsular vaccine for preventing mastitis in two herds in Georgia.

An encapsulated staphylococcal vaccine, consisting of heat-killed capsular-type A and B Staphylococcus aureus strains and capsular polysaccharide extracted from strain ATCC 31432 of Staphylococcus epidermidis, was used to control bovine mastitis in two herds in Georgia. The vaccine was administered intramuscularly into 97 and 125 cows in the herds, and equal numbers of animals were controls. Two weeks after primary vaccination a booster injection was given. No side effects were observed. In one herd, leucocyte content of milk samples decreased remarkably 1 wk after the booster injection. Significant resistance to infection was maintained for 4 mo after vaccination. Estimation of the total loss of milk yield showed less loss compared to that in the control group for 4 mo after vaccination. In the other herd, remarkable improvements of milk samples were observed as early as 1 wk after primary vaccination and resistance to infection continued for 6 mo after vaccination, when experiments were terminated. At 3 mo after vaccination, loss of milk yield was approximately one-third of that in the control group, and this reduction of loss was maintained for 6 mo after vaccination.