Mastitis remains the most costly problem in the dairy industry after decades of research with intense focus on management practices and the introduction of modern equipment. Published research reveals that one-third of all dairy cows are estimated to have mastitis and that 50 percent of cows in Canada and the U.S. have one or more infected quarters.

The report “The Dairy Industry in Israel 2012” documents the fact that approximately 50 percent of milk processed in Israel is from cows with an SCC more than 200,000 – the level considered to represent subclinical infections.

Mastitis is likely the most studied problem in the dairy industry, with more than 4,000 publications listed in the Journal of Dairy Science alone on that topic. The investigations to date focus on the environment and management practices that are believed to be associated with the bacterial invasion of the udder resulting in the infections.

Accepted practices therefore focus on cleanliness, proper milking procedures and best management practices. Most recently, the industry has come to accept that mastitis is a fact of milking animals and is turning to technology to allow dairy farmers to gather data to better manage cows with infections. This approach does nothing to prevent mastitis but rather focuses on managing the problem.

The published evidence shows that the actions taken to date have not addressed the root cause of the infections and instead has driven up replacement rates. Reports on cows milked with robotics show that contagious mastitis from bacteria such as Staph. aureus remain a serious problem in spite of the very repeatable milking process with a quarter milking machine that self-cleans between each milking.


One study reported that in an automatic milking (robot) herd, where the prevalence of Staph. aureus intramammary infections (IMI) at calving was 3 percent of the cows, the infection spread to 67 percent of the cows during the one-year study period. Another report noted that steaming the liners after milking was not associated with improved udder health. This data suggests that there exists another mechanism for the bacteria to invade the udder.

Research completed by Dr. Derek Forbes in England provides evidence of the method that bacteria can invade the udder even with the best management and cleanliness practices. Forbes determined that non-motile bacteria, such as Staph. aureus, are forced up the teat canal during the milking process by the pinching action of the liner.

He determined that Staph. aureus can remain in the canal for weeks without causing an infection if not forced up the canal. If the contaminated teat canal is pinched by a liner, the result is effectively a reverse milking action that forces the bacteria up the canal to cause an infection.

Forbes’ approach was to extract milk directly from the teat sinus with a syringe to obtain milk that had not passed through the teat canal. The bacteria present in the milk extracted directly from the sinus were compared to those in samples collected from the teat ends by hand milking.

Cows continued to be milked by machine, and samples were regularly collected and the results compared over a period of time. The data gathered shows in some cases the samples collected by hand could have bacteria such as Staph. aureus present for many weeks before an infection was detected in the teat sinus.

Other quarters quickly experienced the movement of bacteria from the teat canal to the teat sinus to cause an IMI. The variation is probably due to the shape and size of the teats, some known to have a predisposition to mastitis. The evidence and data leads to the conclusion that the pinching of the liner on the teat end will forcibly shove the keratin lining of the teat canal carrying the bacteria up into the sinus to cause an IMI.

This action is further supported by a National Mastitis Council (NMC) paper by Mein in which he reports, “Cinefilm and cine-radiographic studies as well as ultra-sonic techniques have shown that about one-third of the milk volume present in a teat sinus just before the liner starts to close is ‘pumped’ back up into the udder cistern by the closing liner.”

There exist videos showing this pumping action of liners driven by conventional milking machines, as well as the simply objective test of placing one’s fingers into a working liner and feeling that action.

The fact that the industry still suffers the serious financial impact of mastitis after decades of research and focus on cleanliness and management is proof that another mechanism of infection exists. The research by Forbes and others strongly suggests that the conventional milking machine is the delivery mechanism for bacteria causing the infections.

Dr. Andrew Johnson stated, “Since the milking machine is one of the best washing machines ever built, the teats are bathed with milk during the milking process,” at the 2004 NMC annual meeting.

Alternating pulsation creates a back-and-forth pushing action within the claw causing milk to be washed up against the teats and is combined with the liner pinching, creating the action to drive the bacteria up the teat canal, effectively making the milking machine the delivery mechanism for new infections.

The dairy industry will never adequately address the mastitis problem until the problem of liner pinch on the teat end is solved, as no amount of cleanliness or management practices will ever prevent the forcible shoving and pumping of bacteria up the teat sinus.

A proven solution to the problem now exists with an innovative pulsation design that eliminates the pinching action of the liner and prevents the backwashing of the teats. The solution requires a very short C-phase pulsator design that can change the dynamics of the liner from a simple pinch on the end of the teat to a gentle compressive massage on the full length of the teat.

The closure of a liner is driven by the vacuum that exists within the liner as the fresh air from the pulsator enters the shell. If that fresh air enters slowly, as it does with a conventional pulsator, the liner will close at the end of the teat where the vacuum is the highest, resulting in a pinching action and pumping of the bacteria and milk back up the teat sinus.

In order for the liner to be pulled closed about the full length of the teat, the fresh air must move very rapidly into the shell, requiring very short C-phase durations of 40 to 80 milliseconds.

The short C-phase with a rapid movement of air into the shell allows the liner to fully close about the length of the teat, providing a gentle compressive massage with benefits similar to compressive socks worn on legs of individuals with poor blood circulation.

This action eliminates the teat pinching, eliminates the backwash and provides the required massage action to relieve the congestion from the milking action, permitting both a longer rest and milk phase. Cornell University research has demonstrated a 16:1 reduction in new Staph. aureus IMI with this approach.

Other research by Reitsma has proven that a longer rest phase reduces the incident rate of new infections. This is achieved with a pulsator design having one solenoid dedicated to vacuum and the other to fresh air, providing full separation of air and vacuum along with an unrestricted flow of fresh air through the pulsator.

The duration of the milk and rest phases is lengthened with a pulsation rate of 45 ppm to provide the necessary time for a proper rest, resulting in substantial reductions in mastitis and yielding faster milking with improved teat and udder health. PD

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bill gehm

Bill Gehm