Use Caution When Feeding Dairy Cattle High Levels of Concentrate

DS-15-97, Reviewed April 2008
J. W. Schroeder, Dairy Cattle Specialist

Sometimes it is more economical for dairy producers to limit forage intake and feed concentrates more heavily. Drought generally requires producers to limit forage intake because of limited forage availability. The fiber content of the concentrate mixture fed on limited forage rations should be monitored closely to maintain cow health and milk composition.

If 3-5 lbs of hay-equivalent as hay-crop forage cannot be fed, it may be necessary to use a concentrate mixture with a minimum of 10-12 percent crude fiber as fed. This may be accomplished by using certain byproduct ingredients in the formula. These include: pulp feeds, wheat bran or mids, soybean flakes, corn gluten feed, brewers or distillers grains and malt sprouts. Due to their low soluble nitrogen levels, brewers or distillers grains are preferred when little hay is fed to dairy cows.

Most corn and protein supplement type feeds may only contain 5-7 percent crude fiber. In many cases only maximum crude fiber guarantees are given on tags for manufactured feeds or ingredients, so testing to determine fiber level may be necessary.

Heat treatment of starchy grains such as corn, barley and wheat may lower milkfat tests. If milkfat test depression occurs on a pelleted or coarse-textured feed containing flaked, steamed, rolled and pelleted ingredients, switch to a meal-type feed or limit starchy ingredients to not more than 30-35 percent of the mixture.

Buffers may also be considered if milkfat test depression occurs on limited forage and/or
heat-treated concentrates. The inclusion of the following may be helpful: sodium bicarbonate at 1.0-1.5 percent, magnesium oxide at 0.5 percent and sodium bentonite at 2-3 percent of the concentrate mixture or finished feed. Always check the particle-size on silage or haylages if little or no hay is fed and fat tests are low.

Milkfat tests that run 0.3 percent below or above breed average may indicate that the cows are metabolically abnormal. The problem should be alleviated since health and reproduction also may suffer. If necessary, increase levels of normal forage and reduce concentrate intakes appropriately. Most cows cannot remain at normal levels if concentrate intake from all sources (mixtures, top-feeding, etc.) exceeds 2.5 percent of bodyweight daily on an air-dried basis.

Whenever rations fed vary appreciably from the usual, it is more important than ever to test forages and obtain professional help with feed programming. Nitrate and sulfur tests should also be obtained in appropriate situations, especially when forages have been grown and harvested in adverse weather.

Many grains, roughage and forage substitutes do not contain as much protein, minerals and fat-soluble vitamins as good forage. These and other nutrient balance problems must be addressed in feed programming.