When the dry cows’ urine ph went up and down like a roller coaster at Walnut Grove Dairy, Peter van der Vegt knew something was wrong. They needed to start somewhere, says the Fremont, Ind., producer, so he took a close look at the ration. What he found was that the problem stemmed from his 850-cubic-foot TMR mixer — it didn’t empty out completely at each feeding.

The extra 1,000 pounds left in the mixer distorted the dry cows’ ration. The end result was that the 60 cows in the dry pen got too much potassium. Urine pH levels flew up and down as a result, and fresh-cow health took a hit.

That’s when van der Vegt decided to buy a second mixer to feed his smaller dry-cow and fresh-cow groups. Now, one-and-a-half years later, van der Vegt hasn’t regretted his investment once.

Here’s why you, too, might want to consider buying a second mixer for these smaller groups.


Improve mixing accuracy
The recommended rule-of-thumb is to size a TMR mixer so that it meets the needs of both the largest and smallest groups on your dairy. That way, the mixer will have the capacity to blend batches ranging between these two extremes.

That strategy may prevent you from overfilling the mixer when blending large batches. However, it also may increase the inaccuracy of small batches. That’s because a bigger mixer may not do a good job mixing small batches.

That’s not always the case — a lot of it depends on the mixer’s design — but it’s a valid argument, says David Kammel, extension agricultural engineer at the University of Wisconsin.

If your mixer isn’t blending small batches accurately, small groups, like your close-up and fresh cows, may not be getting a consistent diet, which can hurt feed intake at a time when it is already compromised.

Worth the investment

The other problem associated with mixing small batches in a big mixer is that the mixer may not empty completely.

On any given day at Walnut Grove Dairy, you could peer inside van der Vegt’s 850-cubic-foot mixer and see as much as 1,000 pounds of a ration still inside after feeding a large batch. If van der Vegt hadn’t purchased a smaller mixer, the 60 or so cows in the dry-cow pen would still be receiving a sizeable portion of the lactating-cow ration — and the potassium that went along with it. One thousand pounds of feed can really imbalance a small batch of feed fed to just 60 cows.

Yes, it is an expensive decision to buy a second, smaller TMR mixer. But, it is worth it just to get an accurate ration for critical groups like dry and fresh cows.

Since van der Vegt started using a smaller mixer to feed the dry- and fresh-cow rations, his fresh-cow health has vastly improved.

Before the mixer, 30 percent to 40 percent of all cows that freshened on the 600-cow dairy experienced a fresh-cow health problem, like milk fever, ketosis or a displaced abomasum. Now, that number has dropped to just 10 percent. In fact, his health bill is half of what it used to be.

Certainly, other factors — better feed, more attention to fresh cows — helped improve fresh-cow health at the 600-cow dairy, but van der Vegt is convinced the second mixer played a big role in trimming health problems during the first few weeks after calving.

Using a smaller TMR mixer for these two 60-cow groups has been a win-win for van der Vegt. Maybe it’s time to explore if it can be that way for you, too.


A dual-purpose machine

in addition to feeding small groups, a second, smaller TMR mixer can earn its keep by performing these other tasks on the dairy:

  • Grind hay and straw for all rations fed on the dairy.
  • Serve as a backup if the other mixer breaks down.

A second TMR isn’t right for everyone

not everyone wants to invest upward of $30,000 for a second, smaller TMR mixer. Other options for feeding small groups exist. Greg Bethard, a dairy nutrition consultant based in Wytheville, Va., has found these strategies work well on many of his clients’ dairy operations:

  • Feed small groups just once per day. That way, you mix a larger volume of feed in the mixer than if you feed twice per day. Push feed up frequently, though.
  • Feed more than one pen with the same batch of feed. For example, feed the same ration to fresh cows and hospital cows.