Milk harvest is the interaction between cows, people and milking machines, and we control two-thirds of it. In this interaction, we must ensure that cows are fully participating, but what does that even mean? What does full participation entail? Cow participation is strong, continuous milk flow throughout the milking. It is a cow that is calm and shows no signs of fear or stress before, during and after milking.

Cow participation is not something we routinely measure on farms or hear about when talking to a consultant or a producer. We often hear about total production or parlor efficiency, how many pounds of milk a farm is producing, or how well a parlor is being run (turns per hour, cows per hour, pounds per stall, etc). Even though those concepts are important, they do not include the cow’s engagement during milking.

Defining participation

Milk flow can give us an idea of cow participation, and it can be evaluated with milking efficiency. Milking efficiency is defined as the percentage of unit on-time where milk flow is near maximum.

From a Michigan dataset, we observed that the best herds had an average milking efficiency greater than 90%. In other words, a cow from one of these herds had high milk flow during 90% or more of the time she had a milking unit attached. On the other hand, the worst herds in the dataset had milking efficiencies between 60% and 70%. Milking efficiency is mostly affected by issues happening at the beginning or at the end of the milking, due to delaying milk ejection (DME) and overmilking.

Also known as bimodal milk letdown, DME occurs after unit attachment when milk flow is interrupted or starts after 30 seconds. It is mostly caused by insufficient stimulation or by not allowing for enough lag time (time between stimulation and milking unit attachment). It can affect more than 80% of the cows in a herd, with the best herds having less than 7% DME.

Although some studies have reported no impact of DME on milk yield, recent studies have challenged this idea. We now know that cows that have DME can produce between 3-7 pounds less than cows with normal milk letdown during a single milking. Another study revealed that cows do not compensate for the loss of milk in a following milking. A milking with DME results in less milk, and the more often a cow is experiencing DME, the bigger the yield loss.

Overmilking occurs when the milking units continue to be attached after the cow is done milking. Automatic cluster removers have been an important solution to address overmilking. However, it is still present in many herds. Farms can have between none and all their cows being overmilked. Hyperkeratosis and short-time teat change – such as congestion – are well-known consequences of overmilking. Although there’s no impact on yield, overmilking increases the unit-on time and can potentially impact parlor efficiency.

A common negative effect of both DME and overmilking is the high vacuum in the mouthpiece chamber of the liner. Under optimal milk flow and liner fit, where the teat barrel is in contact with the liner walls, the milking vacuum cannot access the mouthpiece chamber, so that area of teat experiences low vacuum. A different scenario occurs when there is no milk flow. With low or no milk flow, the teats collapse and the seal between the teats and the liners is lost, allowing milking vacuum to reach the mouthpiece chamber. This can result in congestion of the teats, repositioning or climbing up of the cups, and discomfort.

Cows let us know when they are not comfortable during milking: They step, kick or try to take the units off (the feared cow-assisted unit remover). At this point, we do not have evidence that low milk flow or poor cow participation during milking causes pain or stress, but it would be hard to say that cows are comfortable if we observed any of the “I am not OK with what I am experiencing” behaviors during milking.

Make miking a comfortable experience

So, is cow participation important? From an efficiency and a well-being perspective, yes, it is. Farms should try to achieve the best milking efficiency and cow participation possible. The key to accomplish this are practices that are aligned with the cow’s physiology and behavior:

• People – Milking technicians should use low-stress animal handling practices.
• Environment – Provide a low-stress environment in the parlor. Avoid slippery floors, high-pitched noises, poor lighting.
• Stimulation and lag time – Plan the premilking udder preparation to meet the cows’ physiological needs.
• Timing milking unit takeoff – No matter if manual or automatic cluster removers are used, remove the units in a timely manner.

Farms can work with their herd veterinarian, consultants or extension services to assess cow participation in the parlor and what actions can be done to make improvements.