A commercial herd of approximately 550 lactating dairy cows was divided into two groups: one was designated as the Control Group and was milked in a routine fashion with conventional milking machines; the other was designated as the QTO Group and was milked with machines equipped with automatic quarter-take-off devices. Certain tests and observations were made on each animal in both groups at approximately 5-week intervals for 22 weeks. The QTO Group of animals was, by chance selection, at a slight disadvantage in terms of health of the udders at the outset of the study. The disadvantage was overcome quickly and, during the balance of the study, the QTO-milked animals maintained an advantage over the control animals. The advantages in favor of the animals milked with the QTO devices included fewer quarters infected with mastitis pathogens, reduced intramammary irritation as evidenced by lower scores for the California Mastitis Test, and fewer teats showing erosions or other abnormalities of the orifice. The differences were significant (P <0.01). Operators of the machines equipped with QTO devices walked 26.6% less during a routine milking than the operators of the conventional milking machines. The difference was significant (P <0.05).
MASTITIS PATHOGENS AND THEIR ANTIMICROBIAL SUSCEPTIBILITY IN EARLY LACTATING DAIRY COWS
