TMR mixers are all the same. Is mix quality that important?

There are reel mixers, three and four auger horizontal mixers and vertical mixers. All designs are a series of compromises and each has its advantages. Some mixers are true TMR (Total Mix Ration) mixers. Because of the poor mix quality of some mixers, a new term is being used to describe them; PMR or Partial Mix Ration mixers.

When recently talking to Dr. Tom Oelberg from Diamond V, he knew of two studies that verified the importance of mix quality. One was a study from 2011 to 2012 in eastern Ontario, Canada, where 22 farms were visited during the summer and winter. The results were part of a larger study investigating the relationship between feed sorting, feeding management and productivity measures of freestall housed dairy cows.

The conclusion is that measures taken to improve TMR composition, in relation to daily variability, may lead to improvements in DMI, milk yield, and efficiency of group housed dairy cows, ultimately increasing herd profitability. (Source: Sova et al. 2014 J. Dairy Sci 97:562-571)

Another source is from a Diamond V research study. It shows that mixes with CV of under 2% had higher milk and energy corrected milk production, with similar dry matter intake, compared to rations with a CV of 4.6% and 5.4 %

We do have a history of producers that switched types of mixers for a short period of time and have increased production. When their old mixers were returned, production went back down. When these same producers traded in their old mixers, their production went back up.

Is mix quality important? Yes; it is very important. Even a 2-lb. increase per day represents an increase of $900 per month, for every 100 cows at $15 milk.

This is not the time to be making any major purchases. How could anyone justify spending money now with low milk prices?

Whether milk prices are high or low, there are only two reasons for any purchase. Will this investment increase my income or reduce my expenses? Some mixers won’t increase your bottom line and you shouldn’t buy them. A TMR mixer can increase your production if it mixes better than your current mixer. Sometimes you can see a production increase in the first few days of the demonstration, but usually it takes longer.

There are two ways a TMR can reduce your expenses. Many producers have out grown their current mixer and they need to upgrade. Also, some TMR mixers are just very slow. They can actually pulverize the ration before the ration is mixed. In either case, for every hour of mixing time you eliminate, you save at least $75 per hour. This represents a savings of $2,250 per month.

The second way a TMR reduces expenses, is to reduce your feed costs. If your ration is being determined by your TMR, it could be costing you money. For example, you have an opportunity to reduce your hay costs by buying round bales, but your current mixer can’t process this product. The same applies to ethanol by-products, cannery waste, high moisture bales and various types of long grass. Your biggest expense is feed, so it represents your biggest opportunity to save money. These savings can be more than the monthly mixer payment.

It’s more important to reduce expenses or increase income, when milk prices are lower.

How do I know if my TMR is mixing?

You have to test your ration.

  1. Someone who is doing a lot of work with TMR mixers and feeding issues is Dr. Tom Oelberg of Diamond V. ( He has been doing on the farm feeding tests for the several years and has evidence that mix quality can be determined with a Penn State shaker box.
  2. There are tests where your ration can be sent out for analysis, but this can be expensive and time consuming.
  3. Tom and I have worked on using candy as a trace element to determine mix quality. It looks like this will work well. We used ½ inch long red licorice that was added with the last ingredient in the ration. This will determine how well the last ingredient added to the ration was mixed. For every foot of feed bunk you will need to add about 10 pieces of candy to the ration. This should allow you to see the red candy as you walk down your feed alley. You can pull out one-foot wide samples of feed from the beginning, middle and end of your feed alley and count the candy pieces for a more accurate reading. We know that mix quality affects production and these are some ways to check.

What types of things affect mix quality?

Nearly everything. Here are some:

  1. The order the ingredients are added to the mixer.
  2. The length of time the ingredients are mixed.
  3. Changes in the moisture in the hay.
  4. The amount of grass in the hay.
  5. Type of bales.
  6. The wear on the knives and plow wing.
  7. Different operators affect the mix quality.

It seems like anything can affect mix quality.

Some types of TMR’s are more sensitive than others. When you are ready to trade, try different units and buy the unit that mixes best. For example, try mixing small batches, full batches and different ingredients. Because so many things affect mix quality, test your rations.

What size mixer do I need?

Mixers are sized by the total cubic feet and pounds of feed they will hold. The smaller of these two factors will determine the capacity of the mixer. Dairy rations are lighter than some beef rations, so you should run out of space in the mixer before you exceed the weight limitations. Because of this, many manufacturers use cubic feet to determine the proper mixer for dairy farms. Dairy cows need between 6 and 7 cubic feet of feed per day. If you use higher percentages of hay in your ration, you should consider using 7 cubic feet per cow per day.

100 dairy cows @ 7 cubic feet per cow = 700 cubic feet of feed per day.

If you feed once per day, your mixer should be about 700 cubic feet. Many producers feed twice per day, so they would need a 350-cubic foot mixer. Keep in mind that if you put the entire round bale in these smaller vertical mixers, you may run out of room. Round bales are very bulky until they get processed, so you may have to size your mixer a little larger.

Do vertical mixers over mix the feed?

First, we have to use the proper terminology. I doubt if “over mixed feed” is possible. Feed is either mixed or it isn’t mixed. A better term may be, “over processed.” Some types of mixers are notorious at reducing the particle size before they mix. The result is a ration that is pulverized before it is mixed.

When manufacturers talk about mixing speed, the real benefit is not just the reduced time it takes to mix feed. The faster you mix, the more control you have in determining particle length. As a mixer runs we know that with each revolution of the screw, reel or augers, at least one of two things are happening. Feed particle size is being reduced and the ration may or may not be mixing. The hard part is to have the mixer mix as fast as possible, so that the ration is mixed long before the particle length is too short. If your mixer can do this, then you control the particle length in the ration by how long you run the mixer. If your mixer reduces particle length before it mixes the ration, you will have an “over processed” or ruined ration.

How small of a ration can I mix in a mixer?

Equipment salesmen will talk about how their mixers will mix small batches and this is very important. Mixer design can greatly affect small batch mixes. Some vertical mixers are actually quite poor with these rations. I have personally had great results with rations as small as 400 lbs. in a single screw mixer with a rated capacity of over 10,000 lbs. This is really the exception. Most mixers can’t do this. In fact, some of these mixers leave that much feed on the screws, so how could they possibly mix these small batches. Twin-screw mixers will never mix as small a ration as a single screw because of the design limitations. If small batch rations are important to you, stay with a single screw mixer.

There are so many variables in rations that it would be very hard to guarantee that your small ration would mix well in any mixer. The good news is that a serious equipment dealer would want you to try your ration first before you would ever commit to buying.

Can I add very small batches of ingredients directly into the mixer?

Adding small batch ingredients to your ration is a difficult problem. I know of one example where producers want to add several ounces of liquid feed supplement to a 10,000-lb. ration. There has to be a limit to how small a batch can be added to a ration with any hope of it being mixed. There isn’t a definitive answer to this, but my source for some guidelines is Dr. Tom Oelberg. He has seen some engineering data that suggests that the limit to mixing a small ingredient with a larger ingredient is 40 to 1. This example would be like adding 250 lbs. of supplement in a 10,000-lb. ration. He has another source from the beef industry that suggests about a 3% limit. This example would be similar to adding 300 lbs. of supplement to a 10,000-lb. ration.

Mixer scales can be set to be very sensitive and read in 1 lb. increments, but just because you can weigh the ingredient doesn’t mean you can mix it. You may be well served if you use these guidelines and do more with premixes with your smaller volume ingredients. These ingredients are usually very dry and they should be premixed with other dry products. Look again at my first example of adding a few ounces of liquid supplement to a 10,000 ration. I don’t see how that could possibly mix well in any mixer.

What is the most important feature to look for in a new mixer?

Some features are related to repair costs and others are related to mixer performance.

Features such as stronger steel, thicker material or special designs, can be important when you look at the purchase price and future repair or replacement costs. There are two areas that have changed in the last 26 years that I have been involved with TMR mixers. The type and amount of feed that goes through a mixer has increased dramatically and how producers have switched to vertical mixers. The two changes are related. Twenty-five years ago, a small reel mixer could feed 12 to 25 million lbs. before rebuilding, if it didn’t process long hay. The heavier auger mixers could process some long hay and the good ones didn’t need new augers until 50 million lbs. Once some manufacturers found out how to get vertical mixers to mix as well as reel and auger mixers, things changed. Because vertical mixers don’t have high pressure pinch points, producers could feed almost anything that cows would eat and these mixers lasted much longer. If a mixer lasts two to four times longer than a competitor, it just spread replacement costs. That is very important.

If a TMR mixer mixes very well, it will improve your herd health, production and weight gain. If it mixes very quickly, it can reduce your labor costs and you can control the particle length of your ration. If your mixer can mix a wide variety of feed ingredients, you may be able to reduce feed costs. There is no one feature that can do all of these things. The most important “benefit” of a mixer is, can it make you more profitable?

TMR mixers are supposed to make money while you own them. If you can save money when you buy them and they last longer than your old mixer, so much the better.

What’s the fastest way to tell if my mixer is mixing?

The fastest way to determine mix quality is probably not the best. If mix quality were always obvious by watching the ration, no one would have a poor mix.

If you don’t have the time to test your mixer, there are some things that you can look for. Get on your mixer platform and watch what’s happening. One basic rule in mixing is that feed has to fall into a cavity in the ration. You cannot crush feed and expect it to mix. These are the three most common mixes that I have seen:

  1. If feed cones up in the middle of the tub and flows down to the bottom along the sides, you are probably getting some mixing action.
  2. If feed is just rotating around the tub or it looks like it is bouncing, there isn’t any top to bottom mixing.
  3. You may see feed moving around the screw, but not near the sidewalls. This feed near the screw is probably being over processed before the rest of the ration gets mixed.

If you have trouble telling what is going on, throw several empty plastic pop bottles in the ration. They should disappear in the ration very quickly and then pop up somewhere else in the ration after a few minutes.

As a final test, stop the mixer once the ration is mixed and open the door. Most of the feed will stay in place and you may be able to see if the ration has “hot” spots.