Brown mid-rib varieties improve quality |

Brown mid-rib varieties improve quality

Deciphering a hay test: Crude protein

By Jerry Volesky and Ben Beckman
Nebraska Extension

Summer annual grasses often are an important part of many hay and pasture plans. As you select a variety to plant this coming summer, choose one with a genetic trait that improves animal nutrition.

Summer annuals like Sudangrass, cane, sorghum-sudan hybrids, forage sorghum, and millet can produce high forage yields even under dry growing conditions. But they tend to be more stemmy and less digestible than many cattle producers prefer. Can they be made better?

The answer is – yes. A natural, genetic trait called BMR (or brown mid-rib) has been used in numerous varieties and hybrids of summer annual grasses for many years. This trait makes them more digestible and enables cattle to extract more energy from these forages.

It received the brown mid-rib name because the mid-rib or vein that runs down the center of each leaf has a brownish tint in summer annual grasses that have this genetic trait. Normally this mid-rib is a cream or whitish color.

The important characteristic is how the BMR gene affects forage quality. Grasses that have the BMR gene produce less lignin than normal plants. Lignin is a complex compound that attaches to fiber components like cellulose in the plant and make it less digestible. Since plants with the BMR gene produce less lignin, more of the fiber can be digested by your cattle, increasing the energy or TDN value of this forage. Grazing studies in Texas found yearlings to have a 12% greater daily gain when grazing a BMR forage compared to a conventional forage. In addition, animals eat more of the stems, reducing waste.

The BMR gene has little other effect on these plants, so they respond like normal plants to other management practices, like planting rate, fertilization, and harvest timing. Give BMR forages a try and I think you will be pleased.

Last week we looked at the impact moisture has on a hay analysis and how the dry and as received values are used to develop and feed a ration. Today, we’ll take a look at crude protein.

Protein values in hay tests are typically reported as percent crude protein (CP). This measures the nitrogen portion of the hay. For cattle and other ruminants, protein serves two functions. First, protein is important for a healthy population of rumen microbes. These microorganisms aid in digesting grasses and hay that the animal alone couldn’t process. However, a consistent source of protein is needed to maintain a functioning population.

Second, protein is important for animal maintenance and growth. All animals will require some base level of protein to survive, but growing animals and animals with additional demands like pregnancy or lactation may require even greater amounts.

In some cases, when hay gets too hot, the nitrogen chemically bonds to carbohydrates and is unavailable for an animal to utilize effectively. This often happens when hay is stored with moisture concentration above 20% or when fermented feeds like silage are harvested below 65% moisture. When this happens, crude protein does not accurately represent the available protein. Often, these feedstuffs are discolored and may have a sweet or tobacco-like odor.

In these cases, adding heat damaged protein or insoluble crude protein test to your analysis is recommended. This will provide an adjusted crude protein content if more than 10% of the reported crude protein is unavailable for animal use and should be the basis used to form the rations.

Understanding protein in a diet may seem straight forward, but can have a few nuances to keep in mind. Protein is critical for proper animal growth and maintenance, as well as healthy rumen function and, if you do find feed that was improperly stored, the damaged proteins need an additional heat damaged protein test to provide true availability.

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