Optimizing the Rumen

In recent years the dairy industry has suffered through a significant amount of price volatility in milk prices and feed prices. Margins seem to spend much more time being minimal or negative. Commercial dairy farms have found it necessary to improve efficiencies, primarily through economies of scale gained through producing more milk per man-hour worked and total volume from increased herd sizes. However, in pursuing profitability on the modern dairy farm, one area often overlooked is feeding efficiencies and optimizing the rumen function of the cow.

Though often poorly understood or ignored on many dairy farms, feed fermentation in the rumen of a dairy cow is the engine that drives milk production. The more fermentation that can occur in the rumen at any given time, the healthier and more productive a cow will be. While there’s nothing wrong with improving labor efficiencies, milking more cows or buying new equipment to do a better job of farming, the real money – the key to maximizing the thin profit margins on dairy farms – is made with cows that produce more milk during their lifetime – and the way to do that is by optimizing rumen function.

Dairy cows and heifers, being ruminants, require diets consisting of a high percentage of forage. It’s the fermentation of the forage fiber – cellulose and hemicellulose – that keeps a rumen functioning properly and efficiently. The more digestible the forages are the more energy that’s produced by the rumen microbes through the fermentation process. A healthy rumen produces more metabolizable energy for the cow as well as more metabolizable amino acids coming from an increased population of microbial protein.

For commercial dairy cows to be productive and profitable, they must convert the feed they consume every day into milk. This only happens when the microbial population – primarily a multitude of different species of bacteria – have an environment in which they can thrive and multiply. And while cows will seldom be unhealthy on a 100 percent forage diet, they will not necessarily be producing to their genetic potential. Balancing diets that enable optimal rumen function requires a careful balance of forages and other feedstuffs and supplements.

Fermentation drivers

The two fundamental factors that drive fermentation in the rumen are: (1) feeding the rumen microbes and (2) stabilizing the rumen environment. Essentially, when we feed a cow, we are really feeding rumen microbes so that they can ferment cellulose and break it down into other products that become the precursors for glucose synthesis. The microbes become part of the protein source that’s absorbed in the small intestine. For all of this to occur, the rumen environment must be oxygen free (anaerobic) and maintain a consistent pH level for the microbes to survive.

Fiber fermenting microbes require a slightly acidic ruminal pH level of 5.8 to 6.8 to survive and do the job of fermentation. If the rumen becomes more acidic – less than 5.8 – the fiber fermenters begin to die off. This situation is diagnosed as subacute rumen acidosis (SARA). Once rumen pH drops below 5.5, the cow is experiencing clinical acidosis at which time her ability to digest feed is severely limited and her health becomes jeopardized. Maintaining this delicate balance in the rumen is the central focus and a key goal of managing dairy cow nutrition.

Farmers’ challenge

The challenge for dairy farmers and nutritionists is to optimize the fermentation process so that the conversion of feed to milk is as efficient as possible. This must be accomplished while keeping feed costs in check. Every feedstuff that is fed to a cow must be analyzed for its nutritional contribution to cow health and milk production. The ongoing quest for many years is to design diets that will optimize rumen fermentation and energy synthesis without a prohibitive rise in feed costs. But, at the same time, for cows to maximize milk production, they must consume more feed dry matter.

Finding that sweet spot where milk production and feeding efficiencies is maximized is an ever-moving target. On the dairy, forage quality changes from year to year and season to season and diets must continually be reevaluated and rebalanced to compensate for those changes. The costs of purchased ingredients such as corn and soybean meal fluctuate daily and all must be evaluated relative to each other. What is often the case, more expensive ingredients will outperform others that are less expensive. While cheap ingredients are attractive, they may not lend themselves to the most optimal combination for performance in a diet.

While the feeding of grain and other starchy feedstuffs has been commonplace in dairy diets for decades, it’s important to understand that excessive levels of those feedstuffs will cause rumen upset. Slug feeding of grains should be completely avoided and whenever and wherever possible, diets should be delivered as a total mixed ration (TMR) to deliver a consistent supply of nutrients to the rumen microbes.

Especially for the high-producing cows in early lactation, the rumen must be a “well-oiled machine” for it to perform at its optimal best. Ruminant biologists are continually looking for new products that will help maximize microbial growth and fermentation of feedstuffs. Some products such as sodium bicarbonate have a proven track record to help stabilize rumen pH with diets that are high in starch. In many cases yeast products have been proven to help support microbial health. More recent products are introducing enzyme cocktails that will assist in breaking down hemicellulose, providing a head start for the rumen microbes. New and improved versions of mycotoxin binders are showing up in the marketplace, too.

On the management side, remember that cows are living creatures that must be treated properly to maximize milk production. While providing access to feed for your cows and encouraging them to eat all day is necessary, they must also have time for rest so that the rumen can ruminate. Scrimping on cow comfort will depress and compromise the digestion process and milk production no matter how intricately a diet may be balanced.

As the dairy industry struggles through yet another period of price volatility, maximizing the efficiency of your cows’ rumens is recognized as becoming more important to maintain a profitable dairy operation. A healthy rumen is a profitable rumen.