VISUAL ASSESSMENT OF FACTORS AFFECTING REVERSE PRESSURE GRADIENTS IN LINERS USING A SIMULATED MILKING DEVICE

Masafumi Enokidani ,  Yoji Inui ,  Hitoshi Kondo ,  Kazuhiro Kawai ,  Yasunori Shinozuka ,  Kento Imao

The backflow of milk resulting from reverse pressure gradients in liners can cause mastitis. In this study, we hypothesized that liner internal diameter, vent location, and pulsation setting can induce backflow. We therefore attempted to clarify the mechanism of backflow using a flow simulated device. We visually analyzed the effects on backflow of the liner junction point (JP) (i.e., the border from the liner to the short milk tube), the liner inlet point (IP) (i.e., a distance of 63 mm from the end of the short milk tube), vent location, and pulsation setting, using high-speed video recordings of water flow in clear silicone liners at seven flow rates (1.0, 1.5, 2.0, 2.5, 3.0, 3.5, and 4.0 kg min-1/quarter). The actual flow rate was approximately half of the flow meter set value due to the effect of the pulsation closing phase (C+D phase) on quarter level. The results showed that the degree of backflow in liners increased considerably with an increase in flow rate and a decrease in liner internal diameter. The degree of backflow was affected considerably more by JP internal diameter than by IP internal diameter, pulsation setting, or vent location. The degree of backflow was not affected significantly by short milk tube vents and mouthpiece vents when JP internal diameter was larger. However, the degree of backflow was very strong when simultaneous pulsation was used, even at low flow rates. The findings showed that the JP internal diameter should be >13.0 mm, IP internal diameter should be >11.0 mm, the pulsation rate should be 60 pulses/min, and the pulsation ratio should be 60:40 when the alternative pulsation setting is used. This information might be useful for preventing intramammary gland infection.

American Society of Agricultural and Biological Engineers

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https://doi.org/10.13031/ja.15305