Proper udder preparation will result in higher peak milk flow and faster milk out times. Milking routines must stress thorough preparation and stimulation of the teats and udder and be consistent among milkers and milking crews for best results.
Milkers must be trained in milking routines. Udder preparation programs must be monitored and reviewed regularly. Ideal udder preparation routine will include: thorough stimulation of the teat ends with some fore-stripping; teat sanitation including 30 second exposure to teat dip at an interval of one minute between fore-stripping and udder attachment.
The dairy industry obviously derives its livelihood by harvesting raw milk from dairy cows and then processing it into a variety of high quality milk products such as pasteurized fluid milk, cheese, ice cream and cultured milk products. At milking time the key is to work with the physiology of the dairy cow so that we harvest her yield, quickly and completely, without creating problems either for the cow or milk quality.
The recent annual meeting of the National Mastitis Council featured a number of presentations by speakers who have developed experience and technical knowledge on this topic. Basic on these discussions it appears that somehow we often allow milking practices that produce problems of one type or another because they violate the basic rules of cow physiology.
Necessity of Milk Letdown
It has been documented repeatedly that a full and complete milk letdown is dependent on the dairy cow receiving proper stimulation at milking time. When this stimulation fails to occur or when the timing and sequence of the steps involved is inappropriate, the end result is frequently sub-optimal.
The dairy cow produces and stores a great percentage of the milk produced between milkings in the alveolar region of the gland where it is produced, rather than in the cisterns of the udders and teats. Consequently proper pre-milking stimulation is critical in order to allow this milk to be released so that it can be harvested. We breed and manage dairy cows to produce huge volumes of milk. Regardless, until letdown is initiated, the majority of this milk remains in the alveolar tissue where it is produced.
We know that stimulating the nerve endings in the teats and teat ends, when done properly, is the ideal way to cause the release of oxytocin from the brain. It then is transported by the blood stream to the udder where it acts to cause milk in the alveolar spaces to be released to the udder and teat cisterns. This is the fundamental basis of milk letdown.
Many of today’s dairy farms are very large and operate up to 24 hours/day. The equipment in use is expensive, sophisticated and durable. Owners expect, after investing large amounts of money in fixed assets, that such assets be fully utilized and generate a reasonable pay back. It is a business and there is nothing wrong with the logic.
Cow, Milking Machine, Man Interaction
Where problems occur often relates to the unique situation where a human being is using a mechanical device to remove milk from a living dairy cow. Given this three-way interaction it is quite possible that problems may occur with any of the three individual components or among the components. Years ago, before milking machines, it was simply man interacting directly with the cow so only two of the three components were involved. In the future, as robotic milkers evolve, machines may be programmed to milk cows in a prescribed manner every time and no direct human involvement will occur. For the foreseeable future however most dairy operations will continue to have the three-way interaction of cow, man and machine and it will have to be managed properly to achieve optimal results.
For example, if the cows are nervous such as first calf heifers, or the udders are very uneven, three teated or sore, it often causes difficulties. These factors tend to put cows under a lot of stress and the stress may override the positive signals normally associated with teat preparation and result in poor letdown. When the equipment does not function properly due to whatever reason, problems! If the milker is unfamiliar with or ignores proper milking procedures, problems! Each of these possibilities is very real and has to be resolved for the overall system to perform up to its potential.
Milk Letdown and Teat and Udder Preparation
One specific topic that I feel needs to be addressed is the actual procedure of milking so that man, machine and cow all perform at their optimum. It starts with understanding the details of milk letdown and the timing of various events.
It is critical to understand what constitutes complete letdown. When cows enter the milking center leaking milk from their udders, it may be misleading. There may be enough milk in the teat cistern to create pressure and leaking. This is common amongst early lactation, high producing cows. This often does not represent true full-scale milk letdown. The way to produce complete milk letdown is to stimulate the teat and teat ends so that the nerves carry signals to the brain and cause natural oxytocin release. This in-turn is carried by the blood supply to the udder where it causes milk letdown. Oxytocin produces an effect in the udder somewhat like squeezing out a sponge.
Milking also requires that the teats be clean, dry and sanitized prior to units being attached in order to be in compliance with milk production rules and regulations. Generally we combine teat sanitation and stimulation of the teat nerve endings into the pre-milking routine. Ideally 2-3 squirts of milk should be removed from each teat. This allows detection of significantly abnormal milk. Squeezing the teats and passage of milk through the teat opening is a strong stimulus promoting oxytocin release.
Following this, pre-milking teat dip should be applied to the teats and left on for a period of approximately 30 seconds for maximum benefit in terms of teat sanitation. The teat end should be rubbed while the teat dip is present to help clean and sanitize the team opening. Finally, a minute after the stripping has been done, teats need to be wiped clean with a single service towel, paper or cloth, and then units should be attached. This interval is critical. Milkers may develop inappropriate habits either through failure to understand the letdown mechanism or due to training that over-emphasizes rapid preparation and unit attachment to save time.
Consequences of Inadequate Teat and Udder Preparation
Frequently what happens is that cows enter the milking facility, teat dip is applied and then within 10-15 seconds it is wiped off and the units are hung. Another routine may involve only a dry wipe of the teats and units are immediately attached. The problem with these approaches is that the pre-milking stimulus is minimal and the cow’s body cannot react and experience a complete letdown in 10-20 seconds. The milk that initially enters the milking cluster is only what was in the teat and udder cisterns and once that is removed there is no milk to harvest until letdown occurs and the tea cistern is filled. This situation may lead to a number of issues, all of which are serious.
One concern is that the liner, for a period of time, is opening and closing on a teat that has no milk. The industry has always been concerned about this issue when it occurs at the end of milking and all automated take-off systems signal machine removal a reasonable time after the flow rate has reached a predetermined low level. This minimizes the time the teat end is exposed to system vacuum with little or no milk flowing. While there may still be a bit of milk left in the gland, the benefits of getting the unit off promptly far outweigh the benefits of harvesting this small volume of residual milk. When this same issue occurs at the beginning of milking the negative concerns are the same in terms of possible damage or injury to the teat end.
Early Milking Fall-offs and Liner Squawks
A second concern, when units are attached too soon after initial stimulation, is that the lack of significant milk flow may result in the unit falling off shortly after attachment or experiencing significant liner squawking, both of which are a concern. The reason for these is simple. Attaching units too quickly means the teat has not swelled due to milk letdown resulting in more likelihood of air being able to pass between the liner and the teat wall. Once the teat cistern milk is removed the liner is attempting to hand on to an empty teat. Frequently it can’t and starts to squawk or, worse yet, falls off. Small teated cows and heifers are probably the most vulnerable. This may result in a lot of units having to be reattached at the beginning of milking.
Ideally the milking unit should be attached, approximately one minute after preparation, to a fully distended teat. It will then seal better and stay where it belongs.
Maximizing Peak Milk Flow Rates; Minimizing Milking Time
Finally, there is evidence from a number of studies that indicate properly prepping cows and then attaching milking units approximately one minute later results in higher peak milk flows. This is turn leads to complete milk out in a shorter period of time. Attaching units too quickly after prepping the teats tends to lead to lower peak flows and longer machine on time.
Milking routines therefore need to be developed that allow thorough preparation and stimulation of the teats followed by unit attachment one minute after this is complete. There are a number of routines involving one or more milkers that will allow this to happen but they key is to make it happen the same way every milking. Cows are very much creatures of habit and they respond best to consistent routines. Deviations throw them off because they do not quickly adjust to such challenges.
Milkers need to be trained in the basics so that the proper sequence and timing of events is accomplished. Make the routine available in a written format in the language milkers understand. Generally in the US this will be English, Spanish and Portuguese but occasionally it may have to be in other languages as well. Monitor and review programs routinely so milkers know management is concerned about it and expect that it will be done properly. It is also critical that management accept this approach to milking because it is very tempting to speed up the attachment of units with the idea that time is being saved. In fact the time saved at the front end may be offset by lower peak flows and extended machine on-time which is obviously counter productive.
Rasmussen, M.D. A Review of Milking Preparation: The Science. 2000. National Mastitis Council Annual Meeting Proceedings. 39: 104-110
Johnson, A. P. Proper Milking Routine: They Key to Milk Quality. 2000. National Mastitis Council Annual Proceedings. 39:123-126
Eicker, S., S. Steward, D. Reid and P. Rapnicki. New Tools for Measuring the Effect of Stimulation and Take-Off on Milk Flows. National Mastitis Council Annual Proceedings. 2000. 39:127-133.