The concept of a total mixed ration (TMR) is that everything the cow consumes is mixed together. By doing this, the cow gets the appropriate proportions of the ration in every bite. This means the feed can be left out free choice with little to no worry about acidosis. And dry-matter intakes are maximized. If the quality of ingredients is optimum, the ration is properly formulated and dry-matter intakes increase, milk production should increase without digestive upsets.

However, many producers experience reduction in milk yields, increase in displaced abomasums, increase incidence of founder and increased breeding problems.

Let's consider why such negative results are sometimes observed.

1. Few producers feed a true TMR but actually feed a PMR (partial mixed ration). This means that there is some segment of the feeding program where something is fed individually. This may be grass hay, whole cottonseed or some other feed component that is difficult to mix in a mixing wagon.

   Because it is extremely difficult to control individual intakes of a separate ingredient, the entire concept of avoiding acidosis is removed. When formulating the ration, it is impossible to determine the exact amount consumed of such an ingredient. All you can do is base it on the average that disappears. Within this average there is extreme variation from cow to cow. Here's an example: Free-choice grass hay disappears at 5 lbs./cow/day. The consumption of this grass hay may vary from 0 to 15 lbs. per cow. Add to this that a given cow will vary her intake from 0 to 15 lbs. on different given days. If the feed formulator tries to formulate the ration based on 5 lbs. hay per cow per day, there is a high likelihood that the variations in individual consumption will cause a seesaw effect of acidosis.

   All that can be done is to formulate the PMR as if it were a TMR and let the extra roughage go uncalculated. On the other hand if the extra feed ingredient fed is grain, this approach will not work either.

2. Grinding the roughage causes reduced particle size. This reduces the cow's ability to form a bolus and thereby decreases cud-chewing time. A rumen mat, which is like a crust on a lagoon, is essential to a healthy rumen. To keep this rumen mat, a cow must have forage with ample length. There are ways to measure this length, one with a Penn State, particle-size separator. Just follow the procedure with it. If the particle size is too small, acidosis will result.
3. Mixing too long. It is important to follow the manual given with the mixer. It should tell you what order ingredients should be added and the amount of time for mixing.
4. Have enough moisture to keep the cows from sorting. Several ways can be utilized to get a heterogeneous mixture. If silage or haylage make up the majority of the roughage, sorting usually isn't too bad. However, with larger particle roughage, as previously mentioned, sorting still occurs with haylage and corn-silage diets. The best way to avoid this problem is to have liquid molasses on the farm. This is a long-term commitment, but liquid molasses added to a TMR on the farm can do wonders for the feeding program. Feed about two lbs. of actual wet molasses per cow per day. Not only will it stop the sorting, but it will improve dry-matter intake, reduce wastage and provide valuable sugars to the rumen microbes. MFA can provide liquid molasses to farms through most of our locations.

   Another remedy is to add water. Though this is tedious and really contributes nothing for your time, it can be worth a lot if it adds enough moisture to stop sorting. Water can be added at fairly high rates. Some producers add 400 lbs. per ton. Most nutritionists agree that the ration's total moisture content should not exceed 50 percent.

5. Sodium bicarb can be added to the ration at a rate of 1/4 to 1/2 lb./cow/day. When silage or haylage is a major ingredient of the ration, sodium bicarb shows dramatic improvements in dry-matter intakes and reduction of acidosis.

   It is my opinion that sodium bicarb should always be used to give the producer a cushion for mixing errors, ingredient changes and changes of ingredient moisture.

6. Many TMRs are formulated with a low calcium percentage. Calcium should be greater than 1 percent on a dry-matter basis. Failure to raise calcium to 1 percent or greater increases the incidence of displaced abomasums.

Summary:

It has been proven that when a cow is given a choice of several ingredients she will not balance her ration for energy, protein, fiber or mineral. Therefore, we do the balancing. When we mix a total mixed ration, we have decided what the cow needs. We also have decided that we can mix what it says on paper. We have also decided that we can mix and deliver to the bunk the exact proportions we have balanced for, and that the cow will be getting exactly that mix. If we have done this perfectly, we have a true TMR.

A way to check yourself is to take a sample from the mixer, one from the bunk at delivery time and another from the bunk two hours after eating. If they match the ration on paper, then the ideals discussed with a TMR may come true.