CONVERSATIONS: TMR consistency
Total mixed rations (TMR) should be as consistent as the sun’s rising and setting. That doesn’t happen by itself, though. As producers and their advisors meet in the conference room (or kitchen), the conversation will turn to any of a number of factors that can cause unwanted variations in the herd’s TMRs.
By John Miller
The beauty of properly prepared TMRs is that each bite contains exactly the same proportion of forages and concentrates. Every mouthful delivers a balanced ration. With today’s use of wet ingredients – water, light whey, molasses, etc. – unwanted variations can occur if wet ingredients are not properly applied and mixed.
1) What differences can occur?
The TMR’s uniformity suffers when wet ingredients are improperly added. Consider a recent scenario with a mid-lactation diet that contains liquid whey (see Table 1). Once the TMR was delivered to the feed bunk, five samples of approximately 1.5 lb. each were taken at different locations. Each sample was put through a 3-box Penn State Particle Separator and each fraction was analyzed for moisture.
2) How are cows affected?
Anytime TMRs are not consistent, cows are affected. Consistent TMRs nurture highly efficient rumen environments which support optimal milk production and cow performance. Introducing inconsistencies in the TMR can only hold cows back.
On a day-to-day basis at commercial dairies, there are many variables (including the TMR) and normal bulk tank levels fall within a certain range. Good managers using good protocols typically enjoy a pretty narrow range in bulk tank levels. By using good management, they move the total range ahead a little at a time.
3) What causes notable bulk tank changes?
We find that weather or negative changes in ingredient quality can cause the most noticeable changes in bulk tank levels. Cows are resilient, however, and seem to be able to get through most of these without a lasting effect.
If the TMR’s moisture level varies, the cows will eat to a certain dry matter level; they will adjust their intake until their dry matter threshold is reached. However, if parts of the ration have more (or less) whey or water, they may be getting more (or less) sugar or soluble protein. This then dilutes other nutrients. Plain water could also have the same effect, and cows eating the higher moisture parts of the TMR may not have enough TMR available to eat to their dry matter requirement.
4) What are the major causes TMR variations?
• Inadequate mix time – a few more minutes may make all the difference in getting all ingredients evenly distributed in the load.
• Unevenly adding liquid ingredients – many dairies use a boom with a manifold to add liquids. Have the mixer wagon centered under the boom before adding liquids.
• Overfilling the mixer – too much feed in the mixer adversely affects mixing efficiency. Avoid exceeding the manufacturer’s recommended load size. If ingredients spill over the mixer’s top, it’s probably too full.
• Improperly maintained mixer – regularly perform preventative maintenance including knife replacement and adjusting or replacing the kicker bar.
5) How can I easily flag variations in TMRs?
Have your nutritionist and other advisors keep an eye on your TMR. If the TMR in the bunk doesn’t look well mixed, then it probably isn’t. Regularly climb up and look in the mixer; have the feeder do likewise. If, after a load is discharged, you identify individual ingredients stuck to the walls or floor of the mixer, begin looking for the cause of the problem.
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