Choosing a liner is a complex and difficult task – and an extremely important one. Liners have a huge impact on teat-end health as well as parlor efficiency. Often a particular liner is settled on by a trial-and-error process. With so many liner designs and choices, this process can be quite lengthy. I will attempt to describe the most popular types of liners available.
The first place I went to find research for this topic was the Journal of Dairy Science. I entered a quick search for liner shape and was dismayed with the results.
I know it is not one of the most heavily researched areas in dairy science, but surely there had to be a fair number of scientific journal articles? I was wrong. There were various articles here and there.
But many were older than I am. So I did some more digging, consulted a few people, drew on my own experience – and the following is what I can share with you about liner design.
Traditionally, liners were round. Seems like common sense, right? A round liner will fit a round teat. Seems as basic as that toy toddlers often have, where they try to fit the appropriate shape (square, star, circle, etc.) into the appropriate hole.
But not everything is as simple as it seems. In 1972, a gentlemen by the name of Dan Noorlander was thinking outside the box and pitched the idea to my grandfather and dad for the barrel of a liner to be square.
This story is, in fact, the way things actually came about. I am telling it to preserve a part of dairy history, not to force my family stories on you. At that point, I’m not certain what my grandfather and dad thought about Dan’s idea.
Dan was quite ahead of his time, and this was the biggest change in liner design the industry had seen in a long time. But I do know that my mom (mother of four) did chime in with some sort of evidence that supported the idea of a square liner and gentler massage (I will spare you the details here).
But the basic philosophy behind square and triangular liners is that when a calf nurses, the tongue pushes the teat to the roof of the calf’s mouth, effectively squishing it into a shape that definitely is not round.
Thus, the square and triangular liners are perhaps mimicking Mother Nature more closely than a round liner. Something about it just plain works. Square liners are popular and have certainly withstood the test of time.
There was a very thorough study done on square versus round liners, and it was presented at the National Mastitis Council meeting in 2006. To sum up a very lengthy and technical study, allow me to make two points.
In herds that used square liners compared to herds that used round liners, herds that used squares had less keratinization (a protrusion of keratinized skin at the teat end).
Second, cows milked with round liners will have, on average, 20 percent more cracks on their teats than cows milked with square liners.
In addition to shape, other important considerations are vents and vent placement. Some dairy producers prefer vents to be in the claw. Some prefer the liner to be vented. Either is OK, as long as there is not a vent in both.
Traditionally, vents have been placed somewhere in the barrel of the liner. This placement has proven to be effective for many years and has been used successfully in many herds and with many different types of milking systems.
Recently, however, new vent placement has been introduced into the dairy industry. Liners with a “mouthpiece” vent are now being seen on some farms. Feelings and performance on this vent placement so far are mixed.
Research was presented at this year’s National Mastitis Council meeting that indicated placing the vent at the mouthpiece chamber reduces signs of congestion in the teat after milking.
While this may indeed be true, the materials and methods of the study presented seemed to have some weaknesses.
Additionally, there have been reports from the field of teat irritation in the area of the airflow from the mouthpiece vent, which has led to cracks and rough skin on the teat.
Another common problem we see with these liners is the build-up of “slime” under the mouthpiece. Any time we are not getting equipment completely clean, bacteria can grow.
This can cause problems with your PI counts. A liner that is dirty and harboring bacteria could also lead to udder health issues.
Round, square, triangle, vented, non-vented, mouthpiece vent or a vent in the barrel ... wow, that is a lot of choices. And there are still more decisions to make. What about rubber versus silicone? Silicone, of course, is more expensive, but it lasts longer.
Are you concerned about the up-front cost? Or are you more concerned with how often you will have to change inflations? Most rubber inflations are used for somewhere in the neighborhood of 1,200 cow milkings.
How often you need to change them depends on how many times a day you milk, how many cows you milk and how many milking units you have. Silicone inflations can last from 5,000 cow milkings to more than 8,000 (based on what I have seen and heard from the field).
So even though silicone inflations may be more of an up-front cost, in the long run they should be able to save you money and time since you won’t be changing inflations as often.
Also, silicone is more resistant to cracks, meaning there are less places for bacteria to hang out, multiply and cause high counts or mastitis.
Are you on information overload yet? Let me try to sum up the most important points for you. The liner needs to have a mouthpiece size, barrel circumference and barrel length that can accommodate the average teat size in your herd.
There will always be one cow with small teats that has some squawks and slips, and one cow with large teats that don’t fit in all the way, but for the most part, liner slips and cluster falls should be rare.
When the liner comes off, you should not see rings where the mouthpiece was, excessive swelling or blue teats. These indicate mechanical damage to the teat and will have a variety of negative effects on your herd.
Cows should milk out in a reasonable amount of time and have an adequate massage phase. The liners should also be easily cleaned.
I will leave you with one final piece of advice. Any liner can and will fail if your system is not properly set up for that liner.
When changing liners, it is imperative you set your system to the manufacturer’s recommendations for that liner. Vacuum levels must be assessed, pulsators checked, automatic takeoffs adjusted, etc.
A representative from the manufacturing company should also be available to come to your farm and assist with this. Usually a Digimet, PT-5 or some other type of diagnostic equipment will be used for the evaluation.
And if you truly want to see the effects of new liners in your herd, do not make any other changes when you change the liners. Changing teat dips, types of bedding or even milkers can give a false impression of what the liner actually is or is not accomplishing.
Liner choice is an extremely important piece of your udder health puzzle. Choosing an effective liner for your herd is a decision that should not be taken lightly. PD
References omitted due to space but are available upon request. Click here to email an editor.
