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Managing Your TMRJim Linn, Extension Dairy Specialist A total mixed ration (TMR) should be the best way to feed your dairy cows and heifers. It offers the advantage of providing a balance of all the nutrients an animal needs in each and every mouthful she consumes. However, the best formulated ration can result in poor animal performance and health problems if the TMR is not properly mixed and fed. Let's look at some potential problems in mixing and feeding TMRs. Weighing FeedThe scales on your mixer should be checked every few months because they can become inaccurate. It is important to check the scales at different weights because sometimes they can be accurate at low weights, but inaccurate after several thousand pounds of feed have been added. One way to do this in open-top auger-type mixers is to place a 50-pound feed sack on each corner (200 pounds total) and observe the scale weight. Remove the sacks and begin adding feeds to the mixer. After about a third of the total mix weight has been added, place the sacks back on the corners and check the scale to see if it increased 200 pounds. Repeat this after about two-thirds and all of the feeds have been added to the mixer. Too often we assume if the final weight of the TMR is correct, the individual feed weights must be close to the amount listed for the batch recipe. This is not always true. For example, you could have added 400 pounds too much of one feed and 400 pounds too little of another. A couple of times each month, the weight of all individual feeds and the total weight for the batch should be recorded by someone assisting the feeder. Not adjusting for changing moisture content of feeds is probably one of the major reasons TMRs fail to give the animal performance expected. Determine the moisture content of ensiled and wet feeds at least once a week. If the moisture or dry matter (DM) content of a feed is different than what is listed on the feed mixing instructions, you need to adjust the amount of that feed so the ration remains balanced. Mixing the TMRIn general, minor ingredients, minerals, protein supplements, and grains should be added to the mixer first and forages last. However, this varies with mixer type and feeds being mixed, so follow manufacturer recommendations. Overmixing a TMR can lead to inadequate particle size and a mushy mix cows don't particularly relish. A TMR should be completely mixed about four to five minutes after the last feed has been added. If you mix much longer than this, especially with auger mixers, forages and long particles can be ground too fine. Particle size your TMR mix on a particle shaker box. Between 6 and 10 percent of the sample weight should be on the top screen. Undermixing TMRs is a less frequent problem than overmixing, but it can happen when mixers are overfilled. To get the best, most efficient mixing, fill the mixer to only about 90 percent of capacity. Look at mixes as they are being unloaded to evaluate how well they have been mixed. To help avoid overmixing and undermixing problems, develop protocols for mixing feeds that specify ingredient addition order and how long to let the mixer run between feed additions and after all feeds have been added. This will help the people mixing feed and assure more continuity in TMRs when different people are mixing. Adding HayMost feeds can be mixed into TMRs rather easily except one, baled hay. Often baled hay is added to the TMR for "effective fiber" or to provide the fiber needed for good rumination. What generally occurs is the hay gets sorted out in the manger and cows eat grain and the other finer material. When this happens cows develop acidosis symptoms (sore feet, low fat tests, fluctuating or lowered feed intakes, displaced abomasums, or other problems) even though on paper and in the mix there is plenty of "effective fiber." Without grinding or processing hay before adding to most mixers, it is almost impossible to consistently get good mixing of hay into a TMR and prevent cows from sorting. Some points for evaluating whether you are having a problem with hay in your TMR: 1. Are you trying to feed more than 5 pounds of hay per cow per day in your TMR? Sorting is almost impossible to prevent when this amount or more hay is fed without fine-grinding the hay first or having premium quality dry alfalfa hay (160-plus RFV). 2. Particle size your TMR. Between 6 and 10 percent of the sample weight should be on the top screen. Evaluate the top screen material. Is it something cows will eat? It should not be corn cobs or long coarse stems of hay or haylage. If you have more than 15 percent of the sample on the top screen, there is a good chance cows will be sorting through the TMR. 3. Particle size the weighback. Feed refusals or weighback from a pen should ideally be the same as what was fed. If the weight of material on the top screen is more than 10 percentage points higher than the TMR fed, cows are sorting. For example, if your TMR has 15 percent on the top screen and your weighback is 28 percent on the top screen, this is a very good indication cows are sorting. Solutions to sorting problems are few. Hay can be ground finer or reduced in amount fed. If the material being sorted out is long haylage or corn stalks and cobs, there are not many options. Reducing amounts of the refused forages fed can worsen problems as you reduce fiber in the ration and cows continue to sort, reducing fiber intake even more. Addition of molasses or water if the TMR is too dry can sometimes help. So can feeding more fibrous byproduct feeds such as beet pulp or corn gluten feed to replace some of the forage. FeedingThe first feeding every day should always be to a clean bunk or manger. Clean out refusals each day before fresh feed is delivered. Evaluate the refusal for quality and amount. Weighbacks should be the same composition as the TMR fed and no more than 2 percent of the TMR fed. At least 1 percent weighback is needed to assure cows are being full fed. However, as weighback amounts increase, the opportunity for sorting increases. TMRs can be fed once a day, but for best animal performance twice a day feeding is preferred. If you feed once a day, be sure you have adequate bunk space. The average lactating cow will eat 80 to 100 pounds of as-fed per day. As cows eat, they push feed away from them. On flat mangers, push up feed at least four times per day to minimize sorting. |
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