Merrill, W.G., Department of Animal Science, Cornell University, Ithaca, NY 14853-0281.
Sagi, R., Department of Animal Science, Cornell University, Ithaca, NY 14853-0281.
Petersson, L.G., Department of Animal Science, Cornell University, Ithaca, NY 14853-0281.
Bui, T.V., Department of Animal Science, Cornell University, Ithaca, NY 14853-0281.
Erb, H.N., Department of Animal Science, Cornell University, Ithaca, NY 14853-0281.
Galton, D.M., Department of Animal Science, Cornell University, Ithaca, NY 14853-0281.
Gates, R., Department of Animal Science, Cornell University, Ithaca, NY 14853-0281.

Effects of premilking preparation on complete lactation performance were measured with two groups of multiparous Holstein cows; 1) 17 cows received full stimulation, a 60-s routine, and 2) 16 cows received minimum stimulation, a 15-s routine, before machine attachment. Actual unadjusted average lactation milk yield for cows receiving full stimulation was 5.4% less than that for cows receiving minimum stimulation. When postpeak persistencies were compared by linear regression of either 1) daily milk weights or 2) 3.5% FCM from DHI records of milk yield and milk fat percent and fitted to lactation curves using an incomplete gamma function, cows receiving full stimulation produced 1) 2.8 or 2) 2.5% more milk per lactation than did cows receiving minimal stimulation. However, none of the treatment differences in mean milk yield was significant statistically. Milk flow rates, strip yields, and machine on-times were measured at 8-wk intervals throughout lactation. Cows receiving full stimulation had significantly higher average milk flow rates and shorter machine on-times starting at wk 32. There were no significant differences in strip yields or percent residual milk between cows receiving full and minimum stimulation.