Recent Research and Developments in Machine Milking—A Review

Milking machine research has centered upon the relationship of the machine to mastitis in recent years. Survey data from Denmark indicates 6.6% of infections in problem herds were accounted for by milking machine factors. This review indicates that two factors, pulsation failure and the impact mechanism, consistently influence the new infection rate. Pulsation failure may consist of the mechanical failure of the pulsator, shortness of the liner barrel, or too short a rest phase of the liner. These conditions apparently fail to produce an adequate compressive load on the teat tissue to relieve congestion. The impact phenomena result from an abrupt loss of milking vacuum. Irish workers have concentrated on liner design and milking machine parameters including vacuum reserve, pulsation phase, rate and ratio, and the relationship to liner slip frequency. Reverse pressure gradients across the streak canal have been shown to occur at the end of milking with simulated liner slip by Cornell University workers. Developments such as liner shields, valved claws, chamber and flow directional claws, and improved liner design have emerged to counteract the effects of teat end impacts and cross infections. Other machine developments include electronic identification and milk metering. Robotic milking is entering the initial stages of investigation.