Accuracy is a measure of how well a total mixed ration (TMR) matches your nutritionist’s formulated specifications; precision refers to the consistency or variability inherent in the mixer and TMR.
If you hit the target’s bulls-eye, it doesn’t matter if you use a rifle with a precision engineered scope or a crude bow and arrow; you’re just as accurate.
Even when TMR mixers are in perfect working order, they are more like the bow and arrow. We formulate down to the milligram, but we weigh with 10-lb. to 20-lb. precision.
Jeff Weyers, a nutritionist from Stephenville, Texas, and a dairy global technical specialist with Vi-Cor, has some pretty scary videos of "out-of-condition" TMR mixers. These videos will make you want to run right out to your mixer to check it.
Here are some tips to make sure your mixing is as precise and your TMR is as accurate as possible.
1. Look in your mixer. Check for leftover feed and/or mold buildup. Feed tends to stay on top of the screws on vertical mixers and in dead spots if the mixer is out of condition. Load down the sidewall in the middle of the mixer to prevent hang-ups on the screws and augers.
2. If you see any of this, check for wear. Kicker plates should be replaced if they are worn; they are very important for proper mixer operation. Baffles should not be in all the way–that’s just for shipping. They should be in half way, at most. Knives should be sharp; screws or augers should in good condition. The auger’s leading edge should pass close to the mixer wall.
3. Test distribution by dumping a bushel of green tomatoes, potatoes or oranges in the front of the mixer after it’s full. Watch what happens to them as it mixes. They should show up at the back of the mixer within a minute and be distributed all along the feed bunk after you feed.
4. If you have dead spots, try increasing the tractor’s revolutions per minute and watch the mixing process again.
5. Never put any ingredient in the mixer that’s included at less than 20 lb. unless it’s pre-weighed with a more precise scale. Always premix low-inclusion-rate ingredients.
6. Overmixing is rarely a problem with TMR mixers. We’ve heard this about vertical mixers, but in reality, sorting long particles is a more common problem. The mixer should be turning as you load. Don’t layer the ingredients and then turn the mixer on. Rushing a mix will lead to sorting.
7. Liquid feeds help keep the ingredients blended. Choose a liquid with the proper viscosity to reduce clumping and improve blending consistency. Use a T-bar for better distribution over the mixer.
8. Use the inventory and feeder deviation programs in your feed management software. It’s the best way to keep tabs on your mixing accuracy and precision. It’s also a great teaching tool (not a "gotcha" tool) for feeders. Remember, "You don’t know what you don’t know".
RICK LUNDQUIST, Lundquist & Associates, Nutrition Pro-fessionals, based in Duluth, Minn. You can email him at firstname.lastname@example.org.