engleski

A new method of measuring liner overpressure

We present a method of quantifying teatcup liner overpressure (OP) which is non-invasive, may be used during normal milking, and reflects the effects of liner, cow, milking machine settings and stage of milking. Pulsation chamber vacuum was recorded as an amplitude modulated carrier simultaneously with recording of vibration of the short milk tube (SMT) detected by a small vibration transducer coupled thereto. The frequency spectrogram of the vibration transducer signal showed a characteristic signature (validated by 1000 frame/sec video with a transparent liner) indicative of milk flow ; the pulsation chamber vacuum at which milk flow began corresponds to OP. In a paired test of eight cows and two liners, a reference method (OP with limited pulsation (OPlp)) estimated the OPlp difference between the two liners to be 3.1 kPa, p < 0.05, by t-test. Our method estimated the OP difference between the same liners at peak flow to be 4.4 kPa, p <0 .005, by repeated measurements model (SAS PROC MIXED).

eatcup liner overpressure ; milk flow detection ; flow induced vibration

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