Published on Thu, 08/10/2023 - 11:52am
By Heather Smith Thomas.
Feeding a total mixed ration (TMR) helps cattle achieve maximum performance, and for a dairy cow that means more milk. This feeding method was begun in the 1950s, and is now the most common method for feeding high-producing, indoor-housed dairy cows around the world. Optimum production is accomplished by feeding a nutritionally balanced ration, allowing cows to consume as close to their actual energy requirement as possible while maintaining the physical or roughage characteristics of the diet (ration particle size), required for proper rumen function. Advantages and disadvantages of any feeding system, however, must be weighed before choosing a TMR processer.
The advantage of feeding a TMR (total mixed ration) diet is that each cow can consume the necessary level of nutrients in each bite. The mixed ration should include good quality forages and a balance of grains and proteins. The ideal diet for a lactating dairy cow will be different than the diet for a young growing heifer.
There are several strategies that can be used in TMR systems. A separate TMR can be developed for different animal groups. Rations can be formulated for fresh cows, early lactation cows, mid and late lactation animals, and for far-off and close-up dry cows. Multi-group strategies are especially helpful for meeting the needs of dry cows; the dry cows that are due to calve in three weeks have specific nutrient requirements to minimize metabolic diseases after calving, for instance.
The advantage of the TMR is that you are putting all the selected ingredients together, feeding the cattle what they need, versus them choosing what they like or sorting through a ration and eating parts of it. You’ve selected the ingredients to create a balanced diet for that particular class of animal, making a palatable mix that they can’t sort. You can utilize marginal quality forage, chop it and mix it with higher quality ingredients in a balanced diet, to increase production.
With a proper TMR, each mouthful of feed contains the right amount of ingredients for a balanced ration for that particular cow, resulting in a more stable and ideal environment for the rumen microbes. It provides adequate carbohydrates and nitrogen sources and proper rate of rumen breakdown. This can lead to higher levels of protein required by the rumen microbes throughout the day. A 4% increase in feed utilization can be expected when using a TMR compared to a conventional ration of forage and grain fed separately twice daily.
The ability to use feeds with varying rates of breakdown is also enhanced, often enabling even better nutrient utilization. Dairy farmers can also utilize a greater variety of byproduct feeds with a TMR, which can save money. Many things today are used in cattle rations including human food byproducts like citrus pulp, and even outdated foodstuffs like bread, candies, etc.
The incidence of digestive and metabolic problems often decreases when a TMR is fed, and milk production has been shown to be as much as 5% higher with a TMR compared to conventional rations.
For calves and heifers you can get the forage portion of the diet cut to a certain shorter length, so they can readily eat it. They have smaller mouths and don’t like coarse feed so you need to get it down to a smaller particle size.
There are many different TMR machines available today, since most dairies have realized the benefits for the cows and also for labor saving in the feeding program. These mixers contribute not only to quality mixes and more precise nutrition for the cattle but also can improve efficiency on the farm.
Some machines can load themselves, which turns a two-person two-tractor job into a one-person job. Many North American companies make mobile machines and put big tires on them, like any other piece of equipment that has to go through mud, snow or water. This allows the operator to get to silage bags that might be on the far edge of a field. Many machines also have four wheel drive four wheel crab steering that allows the operator to move the large, heavy piece of equipment around in tight spaces or in a barn.
Some of the most important features of a good TMR machine include minimizing the time it takes to load ingredients, and accuracy of weighing/measuring ingredients, which affects the quality of the mix. The dairy is primarily concerned about quality—especially for lactating cows. It’s important to have a specific cut length on forages, for palatability and quality, and to have all of ingredients thoroughly mixed. Producers are generally utilizing a wide range of ingredients. Some are fluffy and light and some are heavy and dense. Some are dry, some are wet, some are long and some are short.
To deal with these differences, some producers pre-process some ingredients, but others don’t. Some TMR mixers have knives on twin screws in the mixing tub, which can be used if forages are put in first, to reduce the particle size down to what is desired, and then all the other ingredient can be added. This can make a very quick mix that is accurate and consistent.
Big round bales are commonly used as the forage source, since many farms find round bales the quickest, easiest and cheapest way to harvest hay. Those bales may be anything from alfalfa to grass to cereal hay or mixed grass-legume hay, etc. depending on the needs of the operation and availability of the forage. Any operation that feeds large amounts of forage and wants to use round bales will generally use feed mixers.
For round bale processing, some TMR mixers have a triangular-shaped auger which makes the pattern around the auger irregular. This breaks down the bale and takes it apart a lot faster. Some also have self-sharpening knives on the auger.
Every feeding situation is a bit different, and the people feeding cattle are looking for the strategies and technologies that work best for that particular operation. In the dairy industry, most of the feed mixers now are vertical mixers, whereas in a high concentrate feedlot diet, people still use a lot of reel-type mixers and also the four-auger type horizontal mixers.
One of the biggest advantages of using a vertical TMR mixer is that you can put a high proportion of long-stemmed material in the ration and continue mixing while processing that feedstuff down to shorter lengths. These mixers can grind, mix and feed, in one process. Long hay or bales do not necessarily need to be pre-cut before being placed in the mixer although doing so will speed up ration preparation time. A good vertical mixer provides versatility because it can process the long-stemmed material as it mixes, or can just mix pre-chopped ingredients.
The material can be dry or wet—many different kinds of commodities—and it will mix even when the mixer is completely full, because it pulls feed from the bottom and pushes it up into the middle. Some mixers start to have dead spots when you fill them up, but a good vertical mixer won’t have this problem if it’s working properly.
You want good mix consistency, and evenness of discharge so there is no variation from the start of feed-out until the end of feed-out. The more consistent the feed, the better performance of the animals.
Some mixers utilize software that advises the operator how to load the machine and what order to load the ingredients and how long to leave it mixing. This optimizes the mixing process and the ingredients at hand, and can repeat it every day, regardless of who the operator is, because the controller is guiding them through the feeding process.
With this software the manager can also input feed costs and see how much feed is used each day, and its cost, and the impact of any deviations that may occur. These machines have been fine-tuned over the years, in terms of the mixing process and being able to feed the animals the same every day. If there is too much variation, changing the diet of the animals, you are changing the environment for the rumen bacteria—and it’s important to keep that as consistent as possible.
An information bulletin from Pennsylvania State University Extension states that a TMR provides greater accuracy in formulation and feeding if managed properly. This requires accurate weighing of the various feedstuffs with calibrated scales. Using feed scales on mixing equipment allows the quantity of each ingredient to be tightly controlled. Accuracy of the scales and mixing system is critical to a TMR system, and a regular maintenance schedule should be followed to make sure they remain accurate.
When a TMR is mixed properly, a cow cannot consume signiﬁcantly more or less of any forage or concentrate than planned in the ration formulation. Parlor and selective feeding can be discontinued or limited to very small amounts to facilitate cow movement, unless speciﬁc milking systems such as robotic milking systems are being used.
The TMR system is adapted to mechanization with a mixer wagon or a stationary mixer with conveyors or mobile feeders. Mixing equipment must be properly maintained and load cells and scales kept in accurate working order. Mixers can be purchased that handle the addition of long hay but the Penn State Extension publication says these are seldom recommended because many of the TMR mixers that chop long forage also break down other feed and silage particles while they are reducing the long hay particle size. A common result is that the entire TMR has reduced particle size because of the operator’s attempt to add a few pounds of long dry hay to the mix.
It is almost always recommended to chop long forage as a separate commodity before adding it to the TMR mixer and to mix for a limited amount of time, following the recommendations by the manufacturer of the mixer. This is generally no more than four to five minutes, just long enough to achieve a good mixture. You don’t want to over-mix or under-mix the feed. Over-mixing can cause serious problems due to grinding and pulverizing the feed, and inadequate mixing can result in less effective feed utilization by the cows, so it is crucial to mix for the proper amount of time.
Forage particles must be of proper size/length. Most forage particles in silage and haylage should range from 3/8 to 3/4 inches long. Forage particles that are very ﬁne, or grain that is too coarse or whole, should be avoided in the ration. Cows sort out long particles due to their less palatable nature and just eat the ﬁner particles in the ration. This can lead to metabolic problems such as subacute ruminal acidosis. By sorting, the cows are reducing their NDF intake and consuming more fermentable carbohydrates and less effective ﬁber than the formulated ration, and are not receiving a balanced diet.
The Penn State publication also states that feed analyses are crucial; the ration should always be based on forage analysis reports. Current recommendations are to take the average of at least two separate and independent forage analyses from the same lab before building a TMR. It is important to make ration adjustments whenever there is a change in forage. The dry matter of ensiled material should also be checked frequently. The success of using a TMR depends on many factors and close attention to proper management.