EAST LANSING, MI
The milking system is the heart of any dairy operation, so give it the ample consideration it deserves, said Dr. Roger Thomson, internationally acclaimed milk quality consultant, during a DAIReXNET webinar hosted by Michigan State University on April 7.
Thomson has been a practicing dairy veterinarian for 35 years. He has specialized in milk quality for the past 15 years, leading to the founding four years ago of MQ-IQ: Consulting Intelligence for A Quality Milk Harvest.
The goal of a milking parlor is to consistently milk clean, dry and stimulated teats quickly, comfortably and completely. Since quickly and comfortably can clearly be in conflict, Thomson advised dairymen to keep these key issues in focus as they design a correctly-functioning parlor or review an existing system..
When designing and directing cow flow, do not let the parlor run out of cows and do not mix cows. Handle cows gently and humanely, and make sure cows don't give up any more than three hours a day to milking.
Two big reasons producers might consider changing their current milking system is to improve mastitis control and milk quality, or to improve milking performance, speed and completeness of milk-out. "These two reasons are often why I am invited to a farm to do a work-up and are the vast majority of why we are looking at parlors these days," Thomson said.
Decreasing energy consumption is another reason, as well as decreasing pump wear with lower vacuum, decreasing dirt going through the regulator and aesthetic or cosmetic reasons.
The complete milking system should be evaluated annually with milking time testing. However, modern parlors often run 18 hours or more a day and need more frequent evaluation.
"The milking system is an important segment of the dairy business," Thomson said. "We have to remind producers that maintenance on the parlor is very important, and it's easy to overlook."
Parlors operating 24 hours a day can be stacking up 8,760 hours a year, Thomson said. At a minimum, these busy parlors need monthly checks. Measure vacuum levels, perform unit drop-off tests, measure vacuum regulator efficiency and graph pulsators every month.
The valuations are outlined perfectly in the National Mastitis Council's Air Flow Manual, which is available online at NMC's website, Thomson noted. The manual is the gold standard for monitoring parlors and helps ensure that correct strategies are used and consistency is maintained.
There are three key areas of greatest concern for wear and fatigue: the regulator/variable speed (VS) drive function, pulsator function and liner function.
For regular maintenance and correct functioning, he recommended cleaning the regulators monthly, especially air-lubricated regulators. Clean and rebuild direct pulsators at 2,500 hours and indirect pulsators at 4,500 hours.
Every six months, replace rubber goods; gaskets and milk hoses; twin pulsation tubes and short pulsation tubes. Often hoses are neglected and can be left in place for months and even years. That is unacceptable, Thompson said.
Of all the components, the liner is the one part of the milking system that physically touches the cow. "It has a big part to play on the overall comfort of the milk-out and the overall comfort of the cow," he said.
Liners fatigue and wear out and should be replaced every 1,200 to 10,000 milkings, depending on the manufacturer. However, since they are sensitive to wash-up chemicals, small herds should base changing them on days of use rather than milkings, Thomson said. He advises replacements every 90 days at maximum.
Although the different materials used to make liners affect their longevity, none are permanent. "Liners need to be changed on a regular schedule," he said.
When sizing a vacuum pump for a parlor, Thomson's rule of thumb is that a basic milking system needs 35 cubic feet per minute and each milking unit, on a running basis, uses approximately 2 to 3 CFMs. Each horse power should produce 10 CFMs.
Bear in mind that lobe pumps are not quite as efficient (85 percent) and that the newer ¾ inch milk line inlets will increase the base need up to 60 CFMs, he added.
Currently, a debate is running among researchers questioning the significance of slight claw vacuum fluctuation. "We used to think it caused a lot of risk from mastitis, but research suggests this is a minor risk for clinical mastitis," Thompson commented. "This is a tweak from what was thought for years, and it is stimulating really robust discussions lately."
That said, a steady claw vacuum level is still considered ideal for the cow and necessary for good, steady milk-out and comfort. This requires a regulator and a variable frequency drive. You want to site the VFD and regulator near the sanitary trap, so it notices vacuum change quickly, Thompson said, repeating the cardinal rule of "air in, vacuum drops; air out, vacuum rises."
Testing system vacuum levels requires test port. "If you go into a parlor and you don't see test ports at certain points, you know this system has never been tested following NMC protocols," he said.
The milk cluster is very important, with research using ultrasound analysis revealing that congestion and chronic swelling in the teat wall correlates with increased risk of chronic mastitis and higher cell counts.
"I'm finding it interesting that we used to think claw vacuum fluctuation was our big criminal, and now we're being told that the health of the teat, blood congestion in the teat, is even a greater risk for elevated cell counts driven by increased rates of clinical mastitis," Thomson said.
Milking claws come in a variety of shapes. There is an ongoing debate on design, although different shapes can work correctly if installed correctly and set up with the right vacuum levels.
Inflations can be rubber or silicone, an array of shapes, vented and unvented. In general, rubber is comfortable and silicone can be, if set up correctly, Thompson said. A round liner matches up with the shape of a teat nicely for a good seal.
For a fact, large bore liners milk out faster than medium bore, which milk out faster than small bore liners. However, large bore liners have lost favor because they create a lot of space for vacuum, and they will change the physical shape of the teats in the herd. "You will create really big-handled cows," Thompson observed, and most are used only in fresh cow parlors for cows with a lot of edema.
Narrow bore liners may milk slower, but ringing is reduced. Most liners used today are medium and narrow bore, Thomson said, as dairymen aim for the ideal balance of maximum speed and minimum ringing.
Shells, which must match the liner, can be metal, plastic, reusable or throwaway and newer non-twist units, which Thomson considers an important aspect. The days of weighting shells are over, he added, as most dairymen opt for lighter-weight plastic shells, liners and claws, which milk cows out just fine.
Draining a cow's milk tank completely is no longer considered the way to go. Over the past two decades, there has been a nationwide experiment underway on milking cows wetter and wetter, Thomson said, noting research reveals that "milking cows very dry is not what we want to do."
There was a period of time, he said, when it was thought that leaving any milk in a cow meant an increased risk of mastitis. "Then we realized that we were doing a lot of damage to teat ends and causing a lot of discomfort by that much dry milking," he said.
Dairymen have been working toward a wetter takeoff, leaving a few squirts of milk in every cow at detach. "To this point, we have not found any point where we've moved too far toward leaving a little milk in the cow, in regards to increased risk of clinical mastitis," he said, adding research is underway to define that point.
To ensure steady vacuum pressure, there are "really good tests" to evaluate air flow. They include a one unit drop-off test for parlors with under 32 milking units, and a two unit drop-off test for parlors over 32 milking units and for parlors under 32 milking units with more than a single milker.
If the system fails the drop-off test based on NMC standards, the effective reserve is an air flow test done at the receiver and, if it has a regulator instead of a BFD drive, then a manual reserve test is done to check the efficacy of the regulator. "These are really good tests," Thomson said.
Using a unique portable milking system he developed as a teaching parlor, Thompson has been reaching out to milk equipment dealers. "They are a hardworking, dedicated group, but a lot of them have never had this kind of training," he noted. "It's been a lot of fun to work with them and get them comfortable with some of these NMC tests. I think more of this needs to be done."