FIELD STUDIES SHOW ASSOCIATIONS BETWEEN PULSATOR CHARACTERISTICS AND UDDER HEALTH

Four different field studies including 64, 140, 850 and 180 herds were used to investigate the association between pulsator characteristics and udder health. The results indicate that the best udder health is f ound in herds with a d phase > 330 ms and a pulsation rate > 55 min(-1 ). A d phase of < 250 ms was associated with significant elevation in bulk milk somatic cell count, a higher incidence of acute clinical mas titis and a higher frequency of cows having mastitis associated with m ajor pathogens (mainly Staphylococcus aureus) as compared with a d pha se of > 331 ms. There was also a significant positive association betw een a shorter d phase and a high incidence of teat lesions needing vet erinary treatment. Herds having no such teat lesions had pulsators wit h significantly longer d phase than herds with teat lesions (300 ms v. 288 ms). These results strongly suggest that in high-line milking mac hines the d phase should not be as short as 250 ms and should preferab ly be similar to 300 ms, and the pulsation rate should be at least > 5 5 cycles min(-1). There was a strong relationship between the effect o f d phase and the rate of pulsation.