Maximizing Rumen Performance in Dairy Cattle


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Focusing on rumen health allows dairy producers and nutritionists to achieve a new level of productivity.

The productivity – and profitability – of the entire dairy operation relies on healthy rumen function. The four compartments of a ruminant’s stomach must operate efficiently and without imbalances for maximum milk production and minimal losses. Advances in dairy production are allowing producers and nutritionists to focus on maximizing rumen function in finer detail than ever before.

Tricia Wood headshot
Tricia Wood

“We’ve been forced into efficiency,” explained Tricia Wood, Ph.D., Dairy Technical Services with Lallemand Animal Nutrition. “The past several years have seen environmental stressors – flooding and droughts, planting delays, and harvest delays – that lead to molds, Clostridia and fungi in the feed. As an industry, we’re realizing how much those bad spoilage microorganisms and toxins have impacted the rumen.”

When the rumen is not functioning well, producers see variations in milk production, lameness issues, and reproduction issues. At the same time, new technology is available to research the microbes living in the rumen and better understand how they affect rumen health, she noted.

Building on existing knowledge, producers are now able to positively affect the rumen environment to help counter variations in forage quality, improve productivity and enhance animal well-being.

Dana Tomlinson headshot
Dana Tomlinson

Dairy digestion

Dairy cattle are designed to digest and utilize fibrous feeds. These components are not well digested by monogastric animals like swine or poultry. This provides a unique opportunity for dairy producers to utilize as feedstuffs the whole corn plant, grasses, hay, and other high-fiber byproducts, explained Dana Tomlinson, Ph.D., a research nutritionist at Zinpro®.

“Harvesting whole-crop forages increases the tonnage yield, rather than just what you get from grain. It’s a God-given opportunity that you get with ruminants: to utilize high-fiber feedstuffs,” he said.

Dairy cow digestion is strongly determined by the microbial populations in the rumen. A large extent of the energy uptake by lactating dairy cows is in the form of volatile fatty acids (VFAs) synthesized in the rumen by this microbial population through the fermentation of feed. Today much more is understood about how to predict and influence the growth of these microbes.

Advances in dairy nutrition

One of the biggest advancements in dairy nutrition has been modeling the rate and extent of what’s digested in the rumen or metabolized as energy and protein, Dr. Tomlinson noted.

“Looking back 25 or 30 years ago, we were balancing diets based on crude protein and total digestible nutrients. Then, we got closer by formulating diets on rumen degradable and undegradable protein, and on different starches, fats and sugars. Today, we can model what’s happening in the rumen and how the animal is using those end products of digestion. It’s completely different today than it was 15 or 20 years ago,” he said.

However, harmful microbes in feed can negatively impact rumen function and nutrient output. Avoiding contaminants has been increasingly difficult due to forage growing concerns. Research has shown that wild spoilage yeasts and molds can reduce dry matter intake, which can cause cows to fall short of their genetic potential for production.

“Quality control of the silage is important to understanding what is digestible in the rumen,” Dr. Wood said. “Protect against bad microbes and spoilage in the feed by treating your silage right by covering the pile with plastic and using a research-proven forage inoculant, especially those that help minimize spoilage, improve the palatability, and retain nutrients in the silage.”

Tweaks to improve productivity

Dairy producers have been early adopters of direct-fed microbials (DFMs) or probiotics, but they aren’t always able to determine the return on investment, Dr. Wood cautioned.

“First, go with a research-backed additive that’s been in trials where the results have been replicated and show improvements in fiber digestion, energy-corrected milk, etc.,” she advised. “It’s really hard to research your own operation. There are too many factors that can muddy the waters.”

She also recommends choosing a company with a robust service program that can help evaluate the DFM on the operation with diagnostics and lab reports. Fecal starch testing is a good tool. In addition, testing rations and silage can help avoid problems initially.

“If you’re having issues with feed digestibility of crops, adding an active dry yeast can be a good insurance policy to ensure the rumen can maximize the energy you’re feeding it,” Dr. Wood advised.

Feeding the rumen bacteria that help in fiber digestion is another DFM option. In addition, providing branched-chain volatile fatty acids (BCVFAs) directly in the ration can help unlock the full potential of nutrients in the ration and, therefore, enhance the production of high-producing cows.

“It’s not uncommon to see herds with an average of 100 pounds of milk per day per cow. You can’t achieve that by not truly balancing those diets down to the very small components, including fatty acids and trace minerals,” Dr. Tomlinson said. “These cattle are like Olympic athletes. You want to give them the best and minimize antagonizing elements that would limit their performance. Including branched-chain volatile fatty acids can fill dietary insufficiencies and take performance to a new level.”

Walking before running

A properly formulated diet is not always a given, Dr. Tomlinson said. An imbalance between forage and grains can lead to digestive upset, rumen dysbiosis, rumen acidosis, and/or sub-acute ruminal acidosis (SARA) – all of which can negatively affect the immune status, performance, and longevity in the herd.

“There are less obvious mistakes, too, like inconsistency in feeding times,” Dr. Tomlinson said. “Ruminants are creatures of habit. They tend to graze at consistent times a day – almost exactly the same time every day. Feeding times must be consistent.”

He also advises noticing where cows actually eat along the bunk, reducing diet sorting, and maintaining proper mixer processes.

Protecting rumen health can help dairy producers achieve steady gains in milk production and animal health, Dr. Wood advised.

“With new technology available, that has helped us realize that we are sometimes maximizing the cows’ output instead of optimizing them – pushing some of our herd too far,” she said. “Maximizing is pushing the cows to get as much milk production as you can get. That might come at the cost of gut health. Optimizing is feeding a good level of fiber that is well digested, with balanced microbes and avoiding contaminants in our feed. That will optimize what the cow is able to produce over a long, healthy lifetime.”


Key Points

  • The ruminant stomach has four compartments: the rumen, reticulum, omasum, and abomasum.
  • Rumen microbes ferment feed to produce volatile fatty acids and microbial protein, which are the cow’s main energy and protein sources. Rumen microbes also produce B vitamins, vitamin K, and amino acids


1 Linn J, Otterby D, Howard T, Shaver R, Hutjens M, and Kilmer, L. The ruminant digestive system. The University of Minnesota Extension. Available at:


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