At the dairy nutrition workshop held in December featuring Mary Beth Hall talking about nutrition and manure, both she and I talked about how Total Mixed Rations are not infallible.
You need to manage TMRs if you want the performance that you are expecting from the cows.
Rations. You probably have heard comments made that on some farms there are three rations for the same group of cows:
* The ration formulated by the nutritionist;
* The ration mixed by the feeder; and
* The ration consumed by the cows.
The goal is to have the cows consume the ration that the nutritionist formulated. So why doesn’t this occur?
Reason one. The nutritionist formulates a ration and feed changes (especially the silages) or unpalatable feeds are used.
Or nutrient composition of feeds change (this can be expected with commodities) or feeds have poor mixing characteristics, thus a poorly mixed TMR.
In any case, the dry matter intake – nutrient intake – is not what is recommended.
Reason two. Feeder puts in the wrong pounds of feed ingredients into the mixer, the dry matter of the feeds changed, adds the wrong feeds, and over- or undermixes the ration.
Reason three. Cows sort out feeds they want and don’t want to eat.
Just stand and watch cows for 20-30 minutes after a batch of TMR is delivered and see if they don’t sort. You will be surprised.
There are also other factors such as weather and bunk condition and management.
Still the way. So, even though TMRs are not perfect, it still is the way to feed cows.
You need to evaluate your TMR and make sure there are no mixing errors.
Some of the mixing errors that have already been mentioned such as at filling, adding the wrong amounts of ingredients or not filling according to the manufacturers recommendation can cause mixing problems.
Over-mixing will decrease particle size and under-mixing will cause a non-uniform TMR to be delivered and possible sorting.
Scales. Another mixing error can occur with scale accuracy. When was the last time you checked the scale with known weights?
You should check the scale with multiple weights from light (25-50 pounds) up to over 300 pounds.
Sometimes cows will sort even with the best-mixed TMR.
Michigan State researchers reported a study of high producing cows fed the same TMRs (balanced for the same nutrients) with the same feed ingredients, except the alfalfa hay was chopped long or short.
The results: cows with higher milk yield sorted against larger particles.
Research. At Wisconsin, a trial using oat silage with different particle size found cows fed TMRs with large oat silage length were able to sort.
When you look at sorting over time, you will find the longer feed is in the bunk more and more sorting is taking place. So how do you control sorting?
Cut back on long forage to 1 to 2 inches in length and reduce the amount of long forage in the ration providing the ration has enough effective fiber.
Eliminate dry hay and improve forage quality and palatability. Add water if the ration is too dry or add a flavor such as molasses.
Evaluate. Finally, you should evaluate the ration being fed. Walk the feed bunk and look at the feed left and the quality. It should be of similar quality as the TMR delivered and you should feed for 3-5 percent leftovers.
Use the Penn State particle separator box. It now has a new screen to improve monitoring of TMRs and we have one in the Northeast District.
Assess. Assess the TMR mixing accuracy.
I like Mike Hutjen’s thumb rules for mixing accuracy. His 1-2-3 thumb rules compares the nutrient content of the computer-generated ration to what is delivered to the bunk.
The crude protein content should be ±1 percent, the ADF (acid detergent fiber) should be ±2 percent and the dry matter should be ±3 percent.
In summary, TMRs are still the best way we know of to feed cows. The mixers manufactured today do an excellent job of mixing.
Put a plan together on your farm to get the job done properly, monitor and evaluate how well the TMR mixing is being done and take corrective action when necessary.
(The author is a dairy agent for OSU Extension in Wayne County. Questions or comments can be sent in care of Farm and Dairy, P.O. Box 38, Salem, OH 44460.)
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