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

Attempts to maximize the efficiency of milking have resulted in several experiments dealing with factors influencing this procedure. According to Snfith and Petersen (1l), 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. ( 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.