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Feeding total mixed rations

Quick facts

Feeding a total mixed ration (TMR) that contains all the feeds and nutrients the cow needs is an effective, efficient and profitable way to feed dairy cows.

Managing TMR daily can make sure your cows receive enough nutrients for good health, milk production and reproduction. 

Proper nutrition leads to healthy and high-performing dairy cows. Cow rations must contain the following:

  • Good quality forages
  • A balance of grains and protein sources
  • Vitamins
  • Minerals

These feed sources provide nutrients needed for milk production, growth and reproduction. You must balance the nutrients in a ration to avoid excesses or deficiencies. Balancing rations to meet your cows’ nutrient needs can optimize feed digestion and use.   

Feeding a total mixed ration (TMR) that contains all the feeds and nutrients the cow needs is an effective, efficient and profitable way to feed dairy cows.

What is a total mixed ration (TMR)?

A TMR is a method of feeding cows that combines feeds formulated to a specific nutrient content into a single feed mix. The mix contains the following feeds.

  • Forages
  • Grains
  • Protein feeds
  • Minerals
  • Vitamins
  • Feed additives

You can offer cows free choice TMR.

Should you feed your cows a TMR?

Advantages of feeding a TMR

  • With every bite or mouthful cows will eat a nutrient-balanced ration.
  • Cows will eat a fixed amount of forages and concentrates needed for good production and health. It’s harder for cows to be picky while eating.

  • A TMR lowers the risk of digestive upset, stabilizes rumen pH and optimizes rumen feed digestion.

    • The rumen microorganisms have a uniform supply of protein and carbohydrates throughout the day. This maximizes rumen fermentation and the production of rumen microbial protein.

  • TMR mixers can reduce the work of feeding cows and save labor costs. A TMR provides more control and accuracy over the amount of feed given than separate ingredients.

  • Feeding a TMR that’s correctly balanced for your cows can increase milk production by 1 to 2.5 kilograms per cow daily.

Disadvantages of feeding a TMR

  • All cows in the group get the same ration. Individual feeding isn’t possible.

  • You need a mixer to correctly feed a TMR.

    • Feed mixers with weighing equipment are expensive.

  • Dry forages such as hay or straw may not mix well in some TMR mixers.

    • You may need more equipment to chop the hay or straw before adding it to the mixer, depending on the type of mixer you use.

  • You need to group cows to use TMR feeding effectively.

  • Cows in a group should be as uniform in milk production and body weight as possible. Differences in milk production (over 10 kilograms per day) or body weights (over 100 kilograms) within a group can result in some cows being over or under-fed. This can increase feed costs or milk production loss.

  • Have at least three lactating cow groups for cost-effective TMR feeding.

Grouping tips for TMR Feeding

In general, producers using TMR should have at least three milk production groups and a dry cow group. Suggested groups for a TMR-fed herd include the following.

Pre-fresh or close-up dry cows (2 to 3 weeks before calving)

Pre-fresh cows have a low dry matter intake (about 10 kilograms per day). They need a high-fiber ration that contains the nutrients they need for the following.

  • Preparing for the calf’s birth

  • Starting lactation

  • Helping prevent metabolic problems

The ration should contain the following:

  • About 3 kilograms of grain

  • 2 to 3 kilograms of good quality hay plus forage like corn silage

  • Proteins

  • Minerals

  • Feed additives needed to make the ration palatable and help prevent metabolic disorders

Fresh cow group (1 to 21 days after calving)

Fresh cows have low dry matter intakes, but high nutrient needs as they start lactation. Their ration should contain enough fiber (2 to 3 kilograms of good quality hay) to help promote good rumen function. It should also contain other forages and concentrates for a good start towards high milk production and entering the high-production group.

High-producing older cow (2nd lactation and greater) group (21 to 180 days in milk)

High-producing older cows reach peak milk production and peak dry matter intake. The goal for feeding this group is to keep high milk production to get cows bred back for next lactation. You can consider this group a reproduction group because heat detection and breeding occurs.

First lactation or first calf heifer group

First lactation cows tend to do better if they have their own group for social and nutrition reasons. These cows reach peak dry matter intake and milk production slower than older cows. Yet they’re more constant in keeping milk production than older cows. This group can stay together for 250 days in milk or more before moving to a late lactation group.

Mid-lactation cows (180 to 250 days in milk)

Mid-lactation cows should be pregnant with milk production averaging 75 to 85 percent of the high group. Feed this group a ration higher in forages and slightly less nutrient dense than the high group ration.

Late lactation pregnant cow group (250 days in milk to dry off)

In this group, you can mix first lactation cows (over 250 days in milk) with older cows if barn space doesn’t allow you to keep first lactation cows separate for the whole lactation. These cows need a high forage ration to maintain milk production and avoid fattening cows.

Far-Off dry cows (220 to 260 days pregnant)

The goal of the dry period is to prepare the cow for the next lactation. The TMR should contain mostly good to medium-quality forages to promote maximum rumen fill and rumination. Cows will need enough protein and proper mineral balance in their ration.

Formulating TMR rations for groups

Balance rations for slightly higher nutrient intake than the group’s average milk production. Use the dry matter (DM) intake of the group to formulate the ration to the desired nutrient amounts. In general, formulate lactating cow rations for milk production about 20 percent above the group average.

For example, if the group averages 26 kilograms of milk daily, formulate rations for 31 kilograms of milk daily. Rations formulated slightly above average milk production can help cows produce more. If they don’t, the extra nutrition can aid in growth or body condition.

Formulate first lactation cow groups for 30 percent above milk production of the group to promote growth.

Moving cows between groups

After calving, move cows to the fresh cow group. Between 14 and 21 days after calving, move healthy cows into the high production group. Keep cows in a high production group until:

  • They’re pregnant,

  • Their milk production drops 10 percent or more below the group’s production average or

  • Their body condition score is greater than 3.

Avoiding milk production drops

Cows usually drop in milk production when moving between groups. To minimize milk production drops, follow these guidelines:

  • Move cows in groups of four or more. Social changes and fighting within groups affect individual cows more than groups of cows.

  • Move cows at feeding time to limit fighting and social upset.

  • Move cows on a regularly scheduled basis.

    • This helps cows get used to moving and facing social changes.

  • If cows moved to a high group don’t reach the group’s average milk production within about five weeks or before 60 days in milk, move them to a lower group.

  • Avoid large changes in ration nutrient content between groups.

    • You can reduce drops in milk production due to nutritional changes by formulating rations for no more than a 9 kilograms milk production difference.

TMR feeding daily

Monitor the following to make sure your cows consume the correct amount of nutrients for good milk production, reproduction and health.

Changes in feed dry matter

Dairy cow rations are formulated on a dry matter basis. The amounts of each feed fed are on an as-is or as-fed basis. Knowing the correct dry matter (100 - percent moisture) of ensiled forages and wet grains and feeds fed in the TMR is key to mixing and feeding a balanced ration.

Use a moisture tester to test all ensiled forages and wet feeds once or twice a week for moisture or dry matter content. You may feed too much if you underestimate the feed’s dry matter content, thinking it has more moisture than it does. You may not feed enough if you overestimate the dry matter of a feed, thinking it has less moisture than it does.

You can notice changes in dry matter content through:

  • Changes in the size or volume of the TMR mixed.

  • Larger than normal amount of feed remaining the next day (usually means feeds have increased in dry matter).

  • No feed remaining the next day (usually means feeds have decreased in dry matter content or increased in moisture).

Number of cows in a group 

Count the number of cows in a group daily before feeding. This will allow you to feed the correct amount per cow.

Daily intake

Increase or decrease the amount of TMR you mix based on daily changes in feed intake. Cows don’t eat the same amount of feed every day. Weather and environmental temperatures greatly affect daily feed intakes. When making changes to a TMR keep the amount of feeds in proportion.

If feed intakes consistently differ 5 percent (about 2 kilograms) as fed from the amount you balanced for, reformulate the ration using the new feed intake.

Order of feeds added to TMR mixer

Auger mixers

Add feeds in this order when using auger mixers.

  1. Grains and other concentrates

  2. Ensiled forages

  3. Dry forages

    • For the best results, chop or grind dry forages coarsely before adding them to the mixer.

Vertical mixers

Add feeds in this order when using vertical mixers with one or two center augers.

  1. Dry or long forages

  2. Grains

  3. Concentrates

  4. Ensiled forages

Mixing time

Mixing times will vary with:

  • Mixer-type (auger or vertical)

  • Amount of feed in the mixer

  • Size of the tractor running the mixer

  • Mixer condition (new or old)

After adding the last feed ingredient, five minutes of mixing should be enough time to thoroughly mix the feed. With vertical mixers, final mixing time after you add all ingredients is often only three to five minutes.

Make sure to not over mix the TMR. If you overmix the TMR, the feed particles will be small, and no long physical fiber will remain. This will lead to rumen upsets, low cud chewing and acidosis (low pH).

How often and when to feed the TMR each day

You can feed a TMR once daily, but twice daily is better, especially during hot, humid summer months. Feeding once in the early morning and once in the evening keeps the feed fresher and promotes feed intake.

Many producers set out the TMR while the cows are in the parlor for milking. After milking, the cows return to the pen and to fresh feed. Cows are most hungry at this time and eating encourages cows to stand. Standing allows the udders to dry off and the teats to seal before lying down.

How often to push feed in towards the pen

Push the TMR in towards the pen six or more times daily. Cows eat the feed closest to them first. They can only reach out about 72 centimeters from the pen for feed. Thus, if feed isn’t regularly within the cows’ reach, less aggressive eaters may not be able to maximize their feed intake.  

Pushing feed regularly is also important in overcrowded pens with feed bunk space less than 46 centimeters per cow.

Sorting of the TMR

Cows are good at using their noses to sort and separate grain from forage in a TMR. Cows usually eat the grain first and leave long forages for later. In doing this, cows unbalance the TMR by eating only grain at one meal. This can lead to acidosis and off-feed problems.

The drier the TMR, the more the cows sort. A TMR should be between 50 and 55 percent dry matter. Feeding the TMR more than once daily or pushing feed in often helps reduce sorting problems.

Feed refusals

Watch for feed refusals daily. Leftover feed in the bunk should look the same as the TMR you’re about to feed. You can tell if cows are sorting and not eating a balanced ration if they leave long forage particles, corn cobs or other single feed ingredients. Chop the long forages or particle feeds finer or replace them with feeds that are harder to sort to avoid this problem.  

TMR particle size

Check TMR particle size every two to four weeks. You can use a Penn State Particle Size Separator box to check your TMR.

Aim for your TMR particle sizes to separate as follows:

  • 3 to 8 percent of feed on the top screen

  • 30 to 50 percent of feed on the middle screen

  • 30 to 50 percent of feed on the lower screen

  • Less than 20 percent of feed on the bottom pan

Long particles in the TMR or more than 10 percent of TMR on the top screen can allow cows to sort the TMR easier.

Mixer scales calibration

Calibrate mixer scales once every three months. Check mixer scales when the mixer is at one-third, two-thirds and full weight capacity. Placing a known amount of weight (25 to 45 kilogram) on each corner of the mixer, at the three weight loads, is a simple way to test the scales.

Author: Jim Linn, former UMN dairy nutritionist

Reviewed in 2023

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