Use
Caution When Feeding Dairy Cattle High Levels of Concentrate
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.
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