Lack of stimulation at milking time reduces profitability

Colleen Kottke
Wisconsin State Farmer
Consistent milking procedures that help to stimulate the milk letdown response and allow for the timely placement and removal of the milking units can improve milk letdown, milk quality and animal health and welfare.

All across the Midwest and beyond, cows step on and off the milking parlor for their daily milkings—a routine that some milkers say they could perform in their sleep.

While those whose jobs entail putting on and taking off milk machines may believe they are following milking protocols by the book, it is the cow that has the final say.

"Milking is so routine that we sometimes fail to really look at it," said Phil Durst of the MIchigan State University Extension. "If milking protocols on the farm aren't being followed consistently, they could be negatively impacting your herd's health and milking efficiency. A lot of dairy producers may say that they're not experiencing problems, but just because you don't see it doesn't mean the cows aren't experiencing it."

Durst along with his MSU Extension colleague Stan Moore shared their findings on a research project analyzing milking prep procedures and how it impacts milk production, cow health and parlor efficiency, during the April Hoard's Dairyman presentation "Milking evaluation reveals costly problems".

Two of the common problems they uncovered during their research were biphasic milking and overmilking.

Using VaDia milking vacuum recording units, researchers were able to record vacuum levels in the front and rear teat cups, the short milk tube, and pulsation line. Since vacuum level and milk flow are inversely related, Durst says the data recorded by the units show each cow's milk let down time, peak flow period and whether or not a biphasic milking or over-milking event occurs.

"What we were trying to measure is the experience of the cow," Moore said. "We think it's valuable to see what's going on in the parlor that we may not readily recognize."

Moore says that many herds are milked by hired help, and many times cows—especially on large dairies—are milked in shifts around the clock, shutting down only to clean the parlor and milking system.

"There's a lot of pressure to get cows through," Moore said. "Even though we emphasize our milking protocols to our employees and provide training, the question is - are they being followed? An evaluation of milking can provide valuable feedback to employees and management."

Moore says unfettered milk flow starts within 10-15 seconds of physical teat stimulation through cleaning, wiping and fore-stripping milk from the teats. This stimulation sends a signal to the pituitary gland in the cow's brain which releases oxytocin into the bloodstream that travels to the udder where it causes the muscle cells which surround milk ducts to contract, starting the milk letdown.

Durst says it takes between 60-90 seconds from the first touch until letdown occurs—a period called "lagtime".

Employees at Brickstead Dairy use a teat scrubber as part of their parlor routine.

"When we were out on some farms, we were seeing some farmers that had accomplished the 10-15 seconds of stimulation just before the milk machine went on. That's really not what we want to see," Durst said.

Without the proper lagtime, biphasic milking is likely to occur. 

"Biphasic milking results when the oxytocin hasn't yet reached the mammary cells at the time the unit is attached. The cow isn't ready to express that milk; the unit may be on but the milk is still in those cells," he said. "The milk flow starts but stops for a period of about 30-120 seconds until the cells release the milk. This is also called delayed milk ejection."

During the study on Michigan farms, Moore says that about 34 percent of the herds evaluated had 30 percent of cows experiencing biphasic milking.

He said biphasic milking events can negatively impact the herd in a number of different ways from uncomfortable cows to increased mastitis incidents or decreased milk production.

"First of all, that cow is uncomfortable. There's congestion in the teat during vacuum without milk flow. That congestion is going to narrow that teat canal, making it difficult for milk to come out," Moore said. "Over time the teat ends can become damaged and rough. Since that makes it more difficult to clean during milking preparation procedures, the cow is at higher risk of mastitis which can impact milk quality."

While delayed milk ejection did not increase milking time, Durst says that research shows that cows with delayed milk ejection eventually produced less milk.

"Normally with full stimulation and adequate lagtime there is a full letdown of milk in less than 30 seconds after that machine is put on. When full letdown took between 30-60 seconds, cows lost on average 3.5 lb. per milking. Letdown time of 60 seconds or longer reduced a cow's milk production by 7 lbs.," he said. "Some cows have delayed milk ejection 100 percent of the milkings, that means they're losing that amount of milk every single time they go into the parlor.

"That's a significant loss that we just can't ignore. The question is why do we have those losses and what can be done about them?" he added.

Making changes

Before changing the milking protocol, Moore recommends owners taking time to find out if employees are adhering to the prescribed milking protocol, especially if there are several people responsible for milking on different shifts and on weekends.

"It's important that everyone is trained and is following the protocol every single time," Moore said.

If the issue is lack of stimulation, Durst and Moore recommend doubling the time on each cow.

"Any investment that you make in increasing stimulation is not going to cost you extra time in the parlor. We fully believe that by increasing stimulation, in time it will improve milk production and teat health," Moore said. "But in order to do that there needs to be a change in attitude in the parlor. Everyone from the owner to the milker hired yesterday has to make a conscious effort to slow down and increase stimulation time as a matter of routine that will be paid back in the end."

Moore says that the pressure to move cows through the parlor on the large herds may lead employees to take shortcuts.

"We really have to stop talking so much about parlor throughput and more about parlor efficiency; how much milk we're getting out of those cows versus how many turns we can get per hour," Moore said.


Taking the milk machine off in a timely manner is just as important as when to put it on at the beginning. Durst says that overmilking cows may prove just as costly. Overmilking occurs when the unit stays on the cow more than 30 seconds after milking is complete.

Taking the milk machine off in a timely manner is just as important as when to put it on at the beginning. Michigan State University Extension officials say that overmilking leads to teat damage that leads to longer milk times.

"We want those milking units to come off with approximately 1/2 to 1 cup of milk is still in the udder," Durst said. "We're not anxious to get every last drop out of the cow, but we don't want to leave tons behind either."

The study performed by Michigan State University Extension staff revealed that 84 percent of herds overmilked their cows.

"We saw great stimulation, lagtime and milk flow. But many of those units were on a good 1 1/2 minutes after the cow was telling us she was done by dancing around or kicking the milk machine off," Durst said. "If you can see rings around the top of the teats or discoloration of the teat ends, that unit was on too long."

Moore says that like biphasic milking, overmilking will also cause detrimental changes in the teats.

"There will thickening of the cell wall, and the cows will milk out even slower in the future because of that," he said. "So every side in the parlor now has an increased milking time of 1-2 minutes because of overmilking. In both cases, that's a dramatic change in your profitability."

Cows standing in the holding area waiting for their herd mates to finish milking are now forced to be away from the feed bunk and water longer. 

"This is more than just about milk production, we're talking about the health effects on cow's feet and legs," Moore said. 

Durst suggests first checking the procedures and then checking the equipment and settings for automatic takeoff units.

"For those milking without automatic detachers, it's an unfortunate guessing game for milkers to be keeping track of what's going on with each of those cows," he said. "Milk a few cows out by hand after the units come off normally to find out how much milk is left. If there's too little then we're overmilking those cows."

Moore says that evaluating milking procedures is a way to identify problems and correct them, not a time to point fingers.

"The units helped us to measure the cow's experience out in the parlor and allowed us to provide education to producers. If you measure something you can set goals and measure progress," Moore said. "The ultimate goal is to reduce non-milking time the unit is on the cow by better stimulation and by removal of the unit when she's milked out. True efficiency is achieved when people and equipment work with the cow."