The influence of some physical characteristics of the milking machine on the rate of new mastitis infections

Abstract

Large differences in new infection rates occurred with half-udder milking machines in which one half of the cluster operated substantially free from vacuum fluctuations while the other half was subjected to various combinations of different types of fluctuation in vacuum. To increase the rate of new infection all teats were contaminated before and after each milking by immersion in a suspension of Streptococcus agalactiae and Str. dysgalactiae. A series of short-duration trials indicated that neither irregular nor cyclic fluctuations in vacuum acting alone were able to increase new infection rate. However, either the Nyhan and Cowhig irregular fluctuation, or a variant of it in combination with cyclic fluctuations in vacuum, was able to do so under the particular experimental conditions used.

Dynamics of teat-end vacuum during machine milking: types, causes and impacts on teat condition and udder health – a literature review

“…Nyhan 1968). Thiel et al (1973) repeated the trials previously conducted by Nyhan and Cowhig (1967) and Nyhan (1968) to show that both irregular and cyclic vacuum fluctuations can have an impact on udder health. In their study, 20 cows were milked in the same way as in the experiments of Nyhan and Cowhig (1967).…”

“…They are the consequence of an infrequent and unplanned air admission into the vacuum system (cf. Figure 1 ;Nyhan 1968;Thiel et al 1973;Thiel 1978). The extent of irregular vacuum fluctuations depends on a combination of several factors, such as the type of milking system (highline or lowline; Beckley & Smith 1962;Østeras & Lund 1980;Reinemann et al 1997) and the milk flow rate at the moment of occurrence (Schmidt et al 1964;Thompson & Miller 1974), the extent and location of occurring sudden air admission (McDonald & Witzel 1968), obstruction to air flow in the system (Whittlestone 1962;McDonald & Witzel 1968;Thompson & Miller 1974), the internal diameter of the short and long milk tubes (McDonald & Witzel 1968), the type of pulsation (alternating or simultaneous pulsation; McDonald & Witzel 1968), functionality of the vacuum control valve (Wilson 1963), and the capacity of the vacuum pump (Beckley & Smith 1962).…”

“…The minimum required claw vacuum depends certainly on the liner characteristics and the capacity of the claw. Thiel et al (1973) showed that the vacuum fluctuations caused by the cyclic movement of the teatcup liner (cyclic fluctuations) in combination with high or low milk flow rates (vacuum drop) did not lead to an increase of udder infection.…”

“…Vacuum fluctuations are differentiated into two typescyclic and irregular vacuum fluctuations -which will be explicitly specified in the following paragraphs. Fluctuations in vacuum are caused either by the recurrent movement of the liner and corresponding milk flow or by sudden excessive air inlets into the system (Nyhan 1968;Thiel et al 1973). …”

“…They might either per se or in combination (vacuum drop, cyclic and irregular vacuum fluctuations) have an impact on milking performance (McDonald & Witzel 1968;Ambord & Bruckmaier 2010) and udder health Cowhig 1968;Nyhan 1968;Thiel et al 1973;Zecconi et al 1992). Negative impacts could comprise teat congestion or oedema, teat canal integrity and the facilitated physical movement of bacteria into the mammary system (Nyhan 1968;Reitsma et al 1981;Bulletin of the International Dairy Federation 215 1987).…”