Total Mixed Rations (TMR) for Dairy Cattle
Total Mixed Rations (TMR) for Dairy Cattle
A Total Mixed Ration (TMR) is a feeding method in which all feed ingredients, including forages, grains, protein sources, minerals, and vitamins, are combined into a single, uniform mix. This type of feeding program is often used in feedlots and dairies—especially dairies. It helps ensure that each bite a cow takes provides balanced nutrition for optimal milk production and health. TMRs are particularly beneficial for high-producing dairy cows, to minimize feed sorting and to ensure consistent nutrient intake.
A separate TMR can be developed for different groups of cattle. Rations are often formulated for fresh cows, early lactation cows, mid- and late-lactation animals, and for far-off and close-up dry cows, or heifers, since they all have different needs
Scott E. Poock, DVM, DABVP, Associate Extension Professor, University of Missouri, says the TMR for a lactating cow at peak lactation will be different than the TMR for a dry cow or heifer. “They have different nutritional requirements and also need to be fed different amounts. It is very important to figure these out and do it correctly,” he says.
“There are some dairies, however, that have just one standard TMR, no matter how many pens of cows they have, and then simply vary the amount they would give each different group. The amount would be different for a first calf heifer, versus a mature cow, for instance. The mature cows will be getting more dry matter than a first-calf heifer,” says Poock.
That’s one strategy, used by some dairies. “Another strategy, especially for larger farms is to design the ration based on those various groups and their needs. They might have a fresh cow diet, a high production diet, a medium and a low production diet. This is more common on the larger dairies because it’s easier to mix an appropriate batch. What’s difficult in doing this is if the batch gets too small. Most feed scales are not that refined for those differences, in small amounts,” he says.
“Even here, at the University of Missouri, where we are only milking 150 to 60 cows, at any given time we might only have 20 cows in the pre-fresh group. If we are only needing 25 pounds of supplement, the scale might call it 25 but it might actually be 29 or maybe only 21. It’s not as accurate for a small batch, so sometimes we’ll move some additional cows in there so we can make it work. Usually we can do a pretty good job with the TMR if we can have more than 30 cows in a group.”
The dry cows’ diet would contain a lot less energy than the lactating cows’ diet. “Holsteins might need about 28 to 30 pounds of dry matter, whereas once they freshen a mature cow might need 45 to 50 pounds of dry matter. When she reaches peak lactation she’ll need 55 to 60 pounds of dry matter. Thus the dry cow diet—far off to pre-fresh—increases in dry matter, energy and protein content, so it’s very important that the producer work with a good nutritionist who can formulate those rations,” says Poock.
There are many software programs to track this. “We have a good one and when we initially put it in we started tracking how accurate our feeding crews were. This is a peer pressure situation; it might be that one feeder is getting the ration right 98% of the time and this one is only 90% or whatever. So these are some important things to track. We also found that when a person is moving cows around, they’d better be moving the numbers in the feed software, too.” It can become fairly technical.
Normally it’s good to have the pens fairly stable, with not a lot of cows moving in and out, to not disrupt the social dynamics of the group. “Of course the fresh cow pen has to keep changing because most dairies have cows calving all the time. This is also the pen where you have to keep the numbers correct. If you fall behind for a couple of days and end up pushing 15 cows, you have to adjust the numbers in the feed software. When we do that, I like to go right from moving the cows to adjusting the numbers for the feed bunk,” he says.
Producers should always be evaluating every facet involved—looking at milk production, looking at bunks and feeders. “When the feeders come in, the first thing they are supposed to do is go look in the barn and see how much feed is left and whether they need to adjust the ration. We also follow milk production, our test dates, etc. When we are in the pens we look at the manure and assess a fecal score—making sure it is right, and consistent,” he explains.
“We also use what’s called the Penn State particle separator. You put some of the feed into that and shake it, and it will tell you if you have the right ratio of particle size in the ration. You need enough fiber to keep the rumen healthy and running like it should, but you don’t want too much long-stem fiber in there because cows will be able to sort it out. This is something cows do exceptionally well, pushing the unwanted feed aside. Just like you and I, they like their dessert first! They eat their favorite feed first and leave the rest. If you don’t do it right, they can sort some out,” says Poock.
“And if you have old cows with young cows, the old cows will eat all the dessert and the young ones only get the ‘salad’. Then you’ll have old cows with acidosis and some young cows with ketosis. Thus it is very important to evaluate this aspect.”
The plus with TMRs and how they can help what you are trying to do is to have every bite the same, for each cow. “Every mouthful of feed she takes in, you’ve mixed it properly and every bite is exactly like every other bite. That’s the goal,” he says.
“One place where we struggle sometimes to get things right, is looking at dry matter, especially when we’ve had a bunch of rain. If there’s been a lot of rain on that bunk and you are not adjusting for that, and you are not looking at dry matter often enough, soon the cows are not receiving enough dry matter. You need to adjust the ration to make sure you are getting the dry matter into that cow that she needs.”
If producers are using just one TMR for the whole herd, Poock says it is important to make sure the reproduction in that herd is excellent. “If you have very many problem breeders or slow breeders that end up in the late lactation or lower production pen, they will get too fat,” he says. Or if they aren’t going to calve on schedule and it’s going to be awhile before they are dried up for the next calf, they will be consuming more nutrients than they need during that time.
“Some farms make that work—feeding every group the same mixed ration and simply adjusting the amount—but the reproduction has to be really good or some cows spend too much time between calves in that lower production group,” he says.
Dr. Pete Erickson, Extension Dairy Specialist, University of New Hampshire, says that using a TMR helps reduce alterations in rumen pH (the acid-base ratio). “There won’t be potential for a slug of grain going into the rumen, dropping the pH and killing the resident bacteria. There are some very successful dairies, however, especially smaller dairies, that feed component diets instead of a TMR. They feed hay and grain separately or haylage, grain and silage separately and do very well. There is an art to it however, in terms of when you feed what,” he says.
“Typically you would feed hay first and then some grain within a couple hours, being careful to not slug the grain. I remember Dr. Mike Hutjens saying it should be no more than 8 pounds at a time. The TMR eliminates that challenge,” says Erickson.
“TMRs are not without their own challenges, however. Cows are very adept at sorting, selecting what they want to eat and discarding the rest. You can watch them and they will move the feed around with their nose and eat only what they want, so some farms try to figure out a way to prevent this problem. To determine whether cows are sorting, you can look at the particle size of the orts (what remains of the meal—ort is the term for feed refusals). Cows that are sorting usually refuse the longer, larger particles, and a person can check for this by looking at how much (what percent) is left on the top screen of your Penn State shaker box (particle separator),” he says.
“To get around this problem, some people add water to the TMR to try to make it stick together better. Others use molasses and other things to make the feed stick together better to decrease the sorting.”
There are different mixes a person would use, for different groups. “A far-off dry cow’s TMR will have a lot more forage and a lot less protein in it than a lactating cow’s TMR. As the dry cow approaches calving, about three weeks prior to calving you’ll want to increase the crude protein, up to about 15%, and also increase some of the grain portion,” says Erickson.
“As the cow approaches calving, her intake will drop (there’s not as much room in the rumen for feed because the fetus is so large, taking up so much space in the abdomen) so we need to make sure she will have enough of the various nutrients she needs. Essentially we make the diet more dense, with a little more protein. The far-off dry cow need about 12% crude protein; when she gets closer to calving we’ll bump it up to 15% crude protein. We’ll also put a little more grain in the diet or feeds that the cow will be consuming when she’s lactating. This allows the rumen microbes to change, to accomplish this,” he says.
Also you need to add something to reduce the chances for hypocalcemia (milk fever). “This might be a dietary cation-ion difference, or a calcium binder. This can help reduce the risk for milk fever after calving. Thus you are doing a couple things; you are increasing the density of the diet and helping reduce hypocalcemia.”
One thing people often don’t realize is that when cattle are fed a diet that’s low in grain, the rumen papillae regress and become shorter, with less surface area for absorption. “So when you put the cow on a pre-fresh diet, with more grain, this will cause the rumen papillae to develop more. Then after calving, those cows can absorb more nutrients in the rumen,” he explains.
Most people start the pre-fresh diet about 3 to 4 weeks before calving. “A Danish study several years ago showed that it probably should be 5 weeks. This is the length of time it takes the rumen papillae to develop again after a high forage diet. This is almost like what happens with a young calf as the rumen develops. The rumen papillae will develop when we feed calves grain starter.”
You want to start feeding some of the ingredients that the cow will get after she calves. “You don’t want to feed anything like sodium bicarbonate; we don’t want to increase the chance for milk fever. Sodium will actually change the blood pH and stimulate the cow to get milk fever. Most of the ingredients, with the exception of anything that’s going to be high in sodium bicarbonate would increase. Some salt is fine, obviously, but definitely no sodium bicarbonate for those cows,” says Erickson.
Lactating cows will have two or three different TMR diets. “Typically post calving there are some huge changes going on in that animal. Her hormones are raging, and if she’s a Holstein she had a calf that weighs about 100 pounds.” That calf took up a lot of space and now everything shifts back into place. It’s a good idea to feed the cow some long-stem hay to help with the musculature of the rumen.
“This hay can be fed for 2 or 3 weeks, in addition to the current TMR. A person could argue that this diet is not a real TMR but is a PMR (partial mixed ration). It’s probably a good idea to feed some long-stem forage just before calving also, to improve the musculature of the rumen and reduce the chances for a displaced abomasum.”
A couple weeks after calving, most people put cows on a high cow diet, and this will vary from farm to farm and by ingredients available on the farm. “Then as the cows progress forward and go past the peak of lactation, they would be fed a medium diet, and then as they taper off in production it would change to a low cow diet, and the cycle starts all over again,” says Erickson.
The high cow diet will have all the best ingredients and supplements. “It will include all the protective proteins and maybe the rumen protective amino acids and maybe some supplemental fat sources. Then as the cow gets post-peak, she probably doesn’t need as much of that anymore and you can back that down—and put your money where the best response will be,” he says. Post-peak, you are trying to maintain or increase body condition and start backing off on some of those ingredients.
Some dairies in regions where small grains are grown utilize what is called the Goldilocks diet for dry cows and feed a lot of straw. “Jim Drackley from the University of Illinois was the researcher who developed that diet,” says Erickson. This is a feeding strategy to provide just the right amount of energy, not too much and not too little, during the dry period. This balanced approach is also known as a controlled-energy or low-energy dry cow ration, and it helps improve the cow’s metabolic health and transition to lactation.
SIDEBAR: FEEDING HEIFERS – Heifers can be fed in a variety of ways. “I have been here at the University of New Hampshire for 28 years. We’ve been feeding heifer calves a TMR, beginning at about 8 to 10 weeks of age. Many people say you can’t do that, but we do, and it works fine. Most people say you need hay and grain, and that’s fine, too, but there’s no reason you can’t feed calves a TMR after you’ve weaned them. The TMR is based on the nutrient requirements of those animals at that age,” he says.
“You can start at about 18% crude protein just after weaning and then gradually drop it as they get older and are given a heavier forage diet—if the forage is fed free choice,” says Erickson.
“There is another way you can feed heifers, which is called precision feeding or limit feeding. This goes back to some work that was done at Penn State several years ago. With this method, heifers are fed based on their nutrient requirements. It’s a bit like humans in our recommended daily allowance, with a certain number of calories, etc. When we think about feeding cattle, we feed in terms of concentration, like percentages and mega-Cals per pound of dry matter, etc. In actuality the animal is eating pounds of protein, grams of calcium, etc. They are eating an amount rather than a percentage.”
So Penn State developed a program in which they feed heifer calves to meet their actual requirements. If you do this correctly, you only have feed in front of them for about an hour and then no feed for 23 hours. “They can actually eat everything they need within one hour, and if you do it correctly they will grow just fine. To make it work however, you need to weigh them once a month and adjust the diet accordingly, and always make sure there is adequate bunk space for every calf to eat at the same time. It will not work if the pens are overcrowded and some don’t get their share,” he says.
“It’s been shown to work, however, if done right. It’s not a better way; it’s just a different way to feed and grow heifers. If dairy producers are interested in this, they should talk with their consulting nutritionist about it, and there is also some data from Penn State on precision feeding heifers,” says Erickson.
“We’ve done it here and I’ve done some research on it, and it is very interesting. The heifers bawl a lot, but they do perform well. One of the things that happens when you do this is that the rumen will shrink and the animal becomes much more efficient in utilizing nutrients. After they mature and become springers you put them in the dry cow pen on a free-choice diet, a couple months before they are due to calve. Then the rumen will respond and grow. It will change into what you would expect; the rumen doesn’t stay small,” he says.
By Heather Smith Thomas
October 2025
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