Pressure in the teat cistern and the mouth of the calf during suckling

Abstract

The principles of today's machine milking techniques have developed since the early 1900s. The original intention to imitate the sucking action of the calf had to be abandoned owing to technical difficulties. Further developments were made on a largely empirical basis and milking technique became a specific complex of tasks, problems and solutions. Consequently, the sucking of the calf was rejected as a model for machine milking. The sucking behaviour and the application of vacuum and/or pressure by the sucking mammalian offspring have been adapted through evolution. Any eventual changes due to ‘recent’ breeding and development of the milking machine remain marginal compared with evolutionary changes.Since the cineradiographic techniques used by Ardran et al. (1957, 1958) it was believed that sucking calves use mainly pressure to transfer a squirt of milk from the proximally closed teat cistern and through the teat canal. The calf creates the pressure by compressing the teat between the tongue and the hard palate from the base of the teat towards the teat end. Cowie (1977) summarized these results as follows: ‘Sucking, that is the production of vacuum within the mouth cavity, is not an essential feature in suckling, although it aids the process. … The act of suckling is thus analogous to hand milking …’. These conclusions were based on visually analysed recordings. McDonald & Witzel (1966) measured pressure in teat cisterns and vacuum at the teat end simultaneously during suckling. Average maximum pressure in the teat cistern was 36·6 kPa and vacuum at the end of the teat averaged −34·6 kPa. These authors concluded that the average differential pressure across the teat canal was 71 kPa. However, this method of calculation gives only the maximal pressure difference and not the average pressure applied by the calf. They noted that vacuum in the teat cistern occurred during the resting phase of a suckling cycle. The calf's sucking technique for single teats during a meal has been analysed (Mayntz, 1996). Further details of pressure and/or vacuum application during suckling at a specific teat remain unknown.The objective of the present study was to extend the current knowledge about milk extraction by sucking calves through continuous and simultaneous measurements of positive and negative pressure in the teat cistern and in the mouth cavity.

Pressure distribution at the teat–liner and teat–calf interfaces

“…Only the teat end is exposed to this high vacuum because the rest of the teat is protected by the support of the tongue and palate of the calf. Otherwise, the teat end is only exposed to high vacuums during half of the suckling time because the vacuum drops during the swallowing of milk by the calf (Rasmussen and Mayntz, 1998). During a suckling period a calf changes between 4 teats; hence, 3 teats can recover.…”

How does the milk removal method affect teat tissue and teat recovery in dairy ewes?

“…However, cows were milked with a higher teat end vacuum than in the present experiment. Although high vacuum levels are generated around the teat end in calf suckling (61 kPa, Rasmussen & Mayntz, 1998), the teat end is only exposed to vacuum for half of the time it is during mechanical milking, as when the calf swallows the milk the vacuum drops to values close to zero (Rasmussen & Mayntz, 1998). Knizkova et al (2005) noted that the degree of stress suffered by the teat during suckling depends on the age of the offspring and the suckling time.…”

“…In the present work, no effect of the lambs’ age was observed, as during experimental period 2 the lambs were 7 d older than in period 1, but the PER×TRT interaction had no significant effect on the variables. Although high vacuum levels are generated around the teat end in calf suckling (61 kPa, Rasmussen & Mayntz, 1998), the teat end is only exposed to vacuum for half of the time it is during mechanical milking, as when the calf swallows the milk the vacuum drops to values close to zero (Rasmussen & Mayntz, 1998).…”

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

“…No long-term impact on udder health by this teat congestion/oedema was detected. The authors assume that the reactions resemble to the physiological teat reactions which would be caused by calf nursing as well (Isaksson & Lind 1992) where pressure applied to the teat cistern by the calf's palate and tongue can vary from >55 kPa to negative (Rasmussen & Mayntz 1998). So, the characteristic changes of the teat tissue during machine milking are apparent, but seem to be reversible, already during later phases of the milking process (Isaksson & Lind 1992).…”