Analysis of Instantaneous Milk Flow Rate Patterns

Abstract

ABSTRACT MEASUREMENTS of instantaneous milk flow rates from unsupported teats (i.e., linerless teat cups) and corresponding analysis of flow charcteristics are presented in this report. Milk flow measurements were made with an ultrasonic flow meter, using techniques described in a previous report (Delwiche, Scott, and Drost, 1980). Data were gathered according to a V fac-torial experiment design, conducted over 16 days on four cows. Parameters investigated were pulsation frequency, 1.0 and 0.3 Hz; pulsation ratio, 63 and 42 percent milk-ing vacuum, 51 and 41 kPa; and quarter, front (right) and rear (left). Milk flow patterns from each test are divided into three stages: the low flow beginning stage (stage 1), the high average flow rate stage (stage 2), and the tapering off stage (stage 3). Within each stage, se-quences of four to 15 milk flow and vacuum pulses are analysed. Treatment effects during stages 1 to 3 are tested for significance by analysis of variance. Peak and average milk flow rates per pulsation cycle are significantly higher for the lower pulsation frequency (0.3 vs. 1.0 Hz). Similarly, the higher vacuum level (51 vs. 41 kPa) yielded significantly higher flow rates. Differences due to the ef-fects of pulsation frequency are greater than differences due to milking vacuum level. Milk flow rate patterns from unsupported teats show distinct smooth muscle ac-tivity affecting flow rate characteristics. Contractions of smooth muscles in the teat and at the teat end produce rhythmic oscillations of the peak milk flow rate from pulse to pulse and determine the overall shape of each milk pulse.