Survey of Liner Characteristics Used in Japan

Abstract

Highlights The vacuum during milking causes teat ends to suck into liners by 7 to 10 cm. Liner rubber is classified as hard or soft. Volume changes are greater in round liners than those of other shapes in the pulsation cycle. Non-round liners did not press completely during the closing phase. The liner shape had a greater effect on liner volume change than the material. ABSTRACT. A variety of liner shapes are used in the dairy industry in Japan, and it is not known which is optimal for maintaining teat-end condition, preventing mastitis, ensuring milk quality, and improving dairy cow and milking system performance. Liners can be generally classified into types based on their internal shape: round, round with ribs on the outside of the liner, triangular, clover-shaped, or square. In addition, liners can be characterized based on the position of the air vent. The optimal combination of air vent location and internal shape for the maintenance of good teat end condition has not been clarified. The aim of this study is to survey liners in Japan to determine the characteristics of liners currently in use. The depth to which the teat end is pulled into the liner during milking was investigated. An experimental vacuum device was fabricated to measure the touch-point and closure-point (the vacuum levels at which the opposite sides of the internal liner surface begin to touch, and the level at which the liner bore completely closes, respectively). In addition, the volume change of the pulsation chamber during the pulsator opening and closing phases was also investigated. The internal shape of the liner was molded when the liner was opened and closed, and the cross-sectional area was compared for each liner type. The findings showed that liner hardness could be characterized as being either soft or hard. The change in the borevolume of round liners during a pulsation cycle, i.e., between the pulsation opening phase and the closing phase, was larger than that observed with the other liners. The cross-sectional area of the molded shape tended to be wider for liners of other shapes than for round liners. This study investigated and compared the characteristics of various types of liners and found that the characteristics varied widely. It is not clear what kind of liner shape is best, and further research is needed. Keywords: Liner internal shape, Overpressure, Pulsation, Teat end condition, Teat end position.