TMR mixers a favorite of cattle producers
University of Minnesota Beef Team
Use of total mixed ration (TMR) mixers mounted on wagons or trucks is on the rise due to greater returns to feeding and cow-calf operations in spite of greater feed and grain prices.
It is fair to say that simply owning and operating a TMR mixer will not automatically increase production efficiency and enhance cattle performance. Owning and operating a TMR mixer requires routine maintenance, as well as considerations for minimum inclusion rate for each ingredient, loading order, and mixing time.
Weekly preventive maintenance is important to reduce breakdowns and to ensure proper diet mixing. This maintenance schedule should include removal of twine and plastic from around augers. These foreign materials reduce effectiveness of the auger during mixing and reduce bearing life.
Knives on augers and kicker plates should be evaluated for wear and fractures. Dull knives will increase mixing time necessary to process forage to proper length. Worn kicker plates leave feed in mixer, which inhibits complete cleanout.
Feed carryover for operations using the same mixer to mix and deliver feed for conventional and natural cattle may affect the operation’s ability to remain certified under certain programs.
Electronic scales should be checked during scheduled preventive maintenance or at least once annually. Bouncing of TMR mixers over road bumps puts extreme stress on scales.
Inaccurate scale readings can lead to great losses, particularly for operators running custom yards. Similarly, for all operators, inaccurate scales can be costly due to reduced efficiency in cattle or resulting metabolic issues from feeding incorrect amounts of certain ingredients.
Preventive maintenance is very important, but proper TMR loading, mixing and delivering is just as important. Under-mixing diets can cause costly losses in performance due to improper doses of vitamins, mineral and additives.
Every producer must evaluate their TMR mixer with their own unique diets and mixing conditions. One simple mixing integrity assessment is to work with your nutritionist to conduct a Penn State shaker box test to determine the length of mixing time required for a consistent mix across all bunks fed from the same load.
Mixing time and loading sequence interact to determine consistent mixing. Typically, loading sequences that provide best results include loading roughage first. Loading roughage first allows more time for knives and the weight of denser ingredients to reduce forage size to proper length.
Fermented feedstuffs should be added next, followed by wet byproducts such as wet distillers grains or corn gluten feed. Dry ingredients, including rolled or high-moisture corn and dried or liquid supplements, should be added last.
Ingredient landing position in the mixer, particularly for small inclusion ingredients is also important. Vertical mixers should never be loaded directly over the center screw as small inclusion ingredient or liquids can be caught on top and never be blended.
At the same time, when making small diet batch sizes in any mixer type, one must ensure ingredients are not loaded where they stick to the side of the TMR mixer or any other place which might prevent proper mixing.
Diets containing extremely low inclusion rates for certain ingredients, particularly dry ingredients, may be difficult to mix properly. Feed additives, vitamins, and mineral mixes must be included in sufficiently large concentrations for the mixer capacity.
Ingredient inclusion at amounts less than five times the scale accuracy should simply be avoided. (Example: If scale accuracy rating is to within 10 pounds the smallest inclusion rate for an ingredient would be 50 pounds).
Simple carriers such as finely processed corn can be used to pre-mix small-inclusion ingredients prior to adding them to the final diet. This will allow for small-inclusion ingredients to be properly mixed into the TMR.
Roughage processing should also be evaluated closely when using a TMR mixer. Depending on the type of TMR mixer available (horizontal vs. vertical), processing hay, straw or cornstalks to desired length before they are loaded into the TMR mixer is critical.
Vertical mixers are designed to process forage whole using a round or square bale; horizontal mixers are not designed for this. On horizontal mixers unprocessed hay that is loaded into the TMR mixer tends to increase horsepower needs and put excess torque on augers and gears as forage balls in and around the augers. Balled forage can lead the mixed diet to have imbalanced nutrient supply.
Even though vertical mixers are designed to process roughage without the need of a bale grinder it can be beneficial to have the forage processed prior to loading the TMR mixer. This simple step allows for blending roughages from multiple bales. This reduces variation and time needed to process a bale in a TMR mixer before adding additional ingredients.
At feeding time (actual loading, mixing and delivering on time everyday) it is important to reduce time-consuming chores better left to non-feeding times so that all cattle are fed in the shortest time using the most consistent method. These chores may include processing hay or pre-mixing small-inclusion ingredients.
Before getting started on your way to improved maintenance, loading, mixing and delivery efficiency, it is important to consult with your nutritionist, the TMR mixer manufacturer, and proceed to test your own TMR mixer for loading order and mixing time.
Using Penn State shaker boxes, your consulting nutritionist can help you analyze ingredient and mixed diet distribution on each sieve at least once a year. This will provide you with information needed to ensure your equipment is working properly, and cattle are receiving the diet ingredients you and your nutritionist feel will work best for the cattle and economic environment.
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