Instantaneous Milk Flow Rate Patterns from Conventional Teat Cups

AN ultrasonic flow meter was inserted in the short milk tube of a conventional two-chambered teat cup and instantaneous milk flow rates were measured during the course of machine milking. Flow rate characteristics were analysed with a pulsator ratio of 60% for pulsation frequencies of 1.0, 0.3, and 0.1 Hz, and vacuum levels of 50 and 35 kPa. A factorial experiment was conducted over six consecutive days on six cows with all treatment combinations. Data were sampled by computer and statistically analysed for treatment effects. Results showed that total flow rates per pulsation cycle were substantially larger than similar measurements made with a linerless milking unit. Large cyclic fluctuations in liner vacuum were observed, affecting liner wall movement, flow direction, and milk pulse phase with respect to pulsator operation. No significant differences between total pulse flow rates were calculated for the different pulsation frequencies or vacuum levels. Flow rates between cows were significantly different, with several animals showing distinct sensitivity to pulsation frequency. Rhythmic oscillation of the peak milk flow rate were measured for five of the six cows at both vacuum levels, but only at the more rapid pulsation frequency.