Influence of low vacuum levels on milking characteristics of sheep, goat and buffalo

Different settings of the operating parameters (pulsator rate, pulsator ratio and vacuum) are used for milking dairy species in different parts of the world. The level of the operating vacuum in machine milking is one of the principal factors which influence the integrity of the tissues and the milk quality. High vacuum levels (>42 kPa) are often used to facilitate the opening of the teat canal by overcoming the biological closing forces whithin the teat sphincter, but can result in severe machine-induced teat tissue damage. In this study characteristics and performances of mechanical milking at low vacuum levels have been investigated in different dairy species. Milking times and milk productions have been obtained from milk emission curves, recorded by electronic milk-meters (LactoCorder®) during the milking at different vacuum levels of sheep, goats and buffaloes. The results of the comparative experiments clearly indicate that a low vacuum level modifies the kinetics of milk emission, the machine-on time and, thus, the throughput of milking system, in all the dairy species considered. Milk yield was satisfactory at any level tested, showing that low vacuums can be adequate to completely empty the udder. Slight differences were found across species concerning the increase in the milking time per head associated with low levels of milking vacuum Our study represents a contribution to encourage the decrease of the working vacuum during mechanical milking, also for those dairy species generally considered hard to be milked, as buffaloes. Milking should be performed applying the lowest vacuum level, compatible with not excessively prolonging milking time, in line with the animal welfare on dairy husbandry.