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Effects of Vacuum Level and Milking Duration on Milk Production, Milking Time and Rate of Milk Flow in Mastitis-Free First Calf Heifers¹

Animal Industries Department, Storrs Agricultural Experiment Station

Geoffrey Beall

Mathematics Department, University of Connecticut, Storrs

ABSTRACT

Attempts to maximize the efficiency of milking have resulted in several experiments dealing with factors influencing this procedure. According to Smith and Petersen (11), increasing the vacuum level from 10 to 12 and 14 in. of mercury resulted in a nonlinear increase in the rate of milking. This increase was postulated as being due to the differences in the opening of the teat meatus with increased negative pressure. Baxter et al. (2) in a short-term experiment using vacuums of 11, 16, and 20 in. of mercury found an increase in the peak rate of flow with an increase in vacuum. By cannulation of the teat, differences between quarters became nonsignificant, indicating that the teat orifice is one of the main factors controlling milk flow. At the higher vacuum levels, increased amounts of strippings were necessitated, apparently caused by teat cup crawling. Whittleston (13), however, reported no significant increase in rate of milking when vacuums as high as 19 in. of mercury were used.

¹ This project was supported in part by funds provided by the Charles M. Cox Co., the DeLaval Separator Co., and the Charles H. Hood Dairy Foundation. These data were taken in part from a thesis presented by the senior author to the Graduate School of the University of Connecticut in partial fulfillment of the requirements for the Master of Science degree.

² Present address: Animal Husbandry Department, Cornell University, Ithaca, N. Y.

³ Present address: Animal Industry Department, North Carolina State College, Raleigh.

⁴ Present address: American Breeders Service, Asheville. N. C.