Sunday morning a group of cows returns from the parlor. They’re ready to eat after the first milking of the day, but stand around instead — hungry and confused. The regular feeder has the day off, which may explain why fresh feed hasn’t been delivered. Finally, around , the substitute feeder delivers fresh feed, and hungry cows hit the bunk hard.

   Due to a breakdown in communication — or perhaps even incompetence or laziness on the substitute feeder’s part — the cows are put in a difficult position. Delaying a crucial feeding by an hour or even a half hour may be all that’s necessary to cause the cows to over-eat, which can trigger sub-acute ruminal acidosis and other problems down the line.   

At a time when milk prices are headed downward, it’s more important than ever to practice good management. Experts agree there are two areas in particular that demand your attention:

  • Good feedbunk management, including a consistent feeding schedule.
  • Periodic checks of forage quality.

 Feed on a consistent schedule
Cows eat inconsistent amounts of feed for various reasons:

  • Weather patterns.
  • Overcrowding.
  • Less dry matter in the ration than prescribed.
  • Poor feed delivery.

When feed isn’t delivered according to the cows’ expectations, it can throw their intakes off whack, creating all kinds of problems.

When cows finally have proper amounts of feed in front of them, they can over-eat.

Normally, a cow can regulate irregular meal patterns “exquisitely” well, says Gary Oetzel, veterinary researcher at the University of Wisconsin and an authority on rumen acidosis. But fluctuating pH levels in the rumen — due to irregular meal patterns and changing rumen microbe populations — can sometimes get the better of her. (On any given day, the pH in a cow’s rumen may fluctuate a half point to a full point — for instance, from 6.3 all the way down to 5.3.)

Usually, if the pH in a cow’s rumen stays above 5.5, there isn’t a problem, Oetzel says. But if the pH drops much below that, the cow will sense that something is wrong and stop eating until the situation corrects itself.

Mild drops in pH can trigger subacute rumen acidosis, but the cow usually pulls out of it by the end of the day (due to her self-correcting actions), Oetzel says. The pattern may repeat itself the following day.

However, with acute cases, the cow doesn’t pull out of it. Usually, there’s some major mistake that throws the cow’s meal patterns way off, pH drops to 5.0 or below, and the animal goes into a terrible downward spiral that can’t be corrected.

Again, various things can trigger subacute or even acute acidosis. “If there’s a fundamental error, it would be allowing the bunk to be empty at a time (the cows) are not expecting it to be empty and they are hungry,” Oetzel says. 

This is just one example of how you can minimize your losses through better feedbunk management. 

Test your forages  
Ken Bolton, extension livestock agent in Jefferson County, Wis., collected TMR samples from 12 herds in Wisconsin and found considerable variation in dry-matter content. (The farms that contributed samples were split down the middle — six were ranked at the top of their county for rolling herd average and six were ranked at the bottom. In addition, Bolton sampled each of the dairies twice at a 60-day interval.)

A quarter of the samples analyzed in Bolton’s study were significantly different in dry-matter content than what they were supposed to be on the ration-formulation sheet. (A significant difference, in this case, was defined as 3 percent or greater.)

Bolton says variation in dry-matter content is the most important variable affecting TMR nutrient composition.


To stretch your feed dollars, keep track of forage dry matter with a food dehydrator or other method.

Certainly, when cows don’t get enough fiber in their diets — because the forage contains more moisture than it should, which throws off scale weights — health problems can develop and milk production suffers. And, if cows bounce back and forth between rations that are low in fiber and adequate in fiber, they will come back hungrier than ever, which may cause them to over-eat and fall into the acidosis cycle described in the previous section.

Don’t blame the feeder — there may be another reason why the ration changes on a day-to-day basis. It may be a change in the dry-matter content, energy value or digestibility of your forages. 

Be sure to benchmark your forages on a regular basis by sending them to a reference lab for analysis. (For more, go to the Dairy Herd Management Web site at, and access the articles “Improve rations with forage benchmarking” and “How does your forage measure up?” from the April 2004 issue.)

And, an article on page 40 describes a simple test for measuring the dry-matter content of the feed.

Check forage dry matter

A certain mix of alfalfa silage, corn silage and concentrate provides 5,000 pounds of dry matter with 28 percent neutral detergent fiber (NDF). 

What if the alfalfa silage changes from 45 percent to 35 percent dry matter, and nothing is done to adjust the mixing ration? Now, when you load the alfalfa-silage portion (3,333 of the 5,000 pounds in the total mix), you are only feeding 1,167 pounds of dry matter from the alfalfa silage instead of 1,500.

The mixed ration now contains 333 fewer pounds of dry matter, and the effective NDF has dropped from 28 percent to 27.3 percent. That, in turn, could short the cows on fiber and throw them off feed.