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Roughage: Essential for Rumen Function

Jul 05, 2016

By: Kelly Whitcomb

Dairy cow nutrition is constantly analyzed by its contents of protein, energy and minerals. We rarely take notice of the fiber we are feeding, whether it’s adequate, and the key role it plays for overall rumen health. Many people feel that a course roughage is utterly useless nutritionally, but in factuality it is extremely valuable in keeping our animals feeling well and performing their best.

A ruminant’s niche in life is their ability to break down complex structural fibers by means of rumination or “foregut fermentation”. They do so via microbial function in their four-chambered stomach, in comparison to “hindgut fermenters” or single-chambered stomachs seen in other mammals, including horses and rabbits. From this degradation process, cows are able to metabolize and produce the milk we consume or use to make other products.

Though long, coarse fiber is considered to be a low quality forage source, it influences a process known as the “roughage effect” which keeps rumen function optimal. This process occurs when stick-like fibers rub against the inner walls of the rumen, stimulating muscle contractions, and stirring up material being digested. This agitation mixes the contents, becoming more bioavailable for the microorganisms to break down and utilize.

Roughage presents an additional benefit by causing cows to regurgitate the material, usually referred to as “chewing their cud”. The saliva being produced during the mastication process contains a buffer which assists in keeping the cow’s stomach pH at desired levels: neutral to slightly acidic. This is important because most dairy cows are being fed a concentrate, along with their forage, that is high in starches or sugars; this creates acidity in the rumen. By feeding a fibrous roughage, the saliva buffers counter balance the acidity from the concentrates, providing a healthy rumen and a happy cow.

So what is considered a good roughage?

A roughage is a component of the dairy cow’s nutrition regime consisting of a high concentration of slowly degradable fiber, such as long stemmed hay. Adequate roughage is long-stemmed, from 3/8 inch to 1.5 inches long (or longer), causing the cow to chew the forage numerous times. A total mixed ration, or TMR, consists of forage, yet contains additional starches and sugars, and is often cut too short to trigger the “roughage effect”.

The importance of feeding roughage to dairy cows is shown through over all rumen health, function, and productivity. Though concentrates are crucial for energy and production, quality fiber will keep the dairy cow vigorous and content.

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