Providing additional feed is a relatively common practice throughout the summer months to boost gains on unproductive pastures. However, producers trying to “stretch the grass” by feeding supplemental protein may be doing their stands or hay supplies more harm than good. Understanding common misconceptions surrounding ruminant physiology could save your pastures and your pockets.
“How much a cow can eat is determined by two factors; how much her rumen can hold (rumen capacity) and how quickly the rumen is emptied so she has room to eat more (rumen passage rate),” says Jay Jenkins, a University of Nebraska extension educator in a recent BeefWatch newsletter.
Jenkins goes on to say that passage rate is affected by diet quality. With lower quality feed comes a slower passage rate. This means that cattle are able to eat more high-quality feed than low-quality feed.
“Supplementing low-quality forage with protein increases animal performance, but it does not ‘stretch’ the grass. It actually allows them to eat more of it,” Jenkins explains.
When feeding hay, supplementing with protein is often beneficial as it enables cattle to eat greater amounts of lower quality forages. Aside from being able to use cheaper hay, additional benefits can be gained in years of more expensive hay. Jenkins points out that producers can “limit-feed” by feeding less than cattle would be able to consume and still attain their nutritional requirements.
“Protein supplement only stretches feed when intake is limited. Protein supplementation increases passage rate, which means that cows can eat more,” Jenkins concludes. “Not only can the cows eat more, but they definitely will eat more if allowed to eat all they want.”