Dairy Specialist Offers Tips For Managing Dairy Cows With Limited Forage
J.W. Schroeder, Dairy Specialist
A short supply of forage is causing special concern among North Dakota dairy producers, says a North Dakota State University dairy specialist, J. W. Schroeder.
"Forage is especially crucial for dairy producers," says Schroeder of the NDSU Extension Service. "Other livestock species can substitute grains or other feedstuffs for most of their forage, but dairy cattle must have minimum amount of forage in the form of long hay, corn silage or haylage to maintain production levels, feed efficiency and health."
"As feed supplies dwindle, producers of all ruminant species will be forced to abandon the ideals of production efficiency and move into a survival mode," he says.
Feed typically represents 40 to 60 percent of the cost to produce milk. If milk yield is forced down by feeding lower-quality forages, an even greater portion of the production dollar will go toward feed, Schroeder says.
For the high-producing dairy cow, about 50 percent of the crude protein and net energy for lactation requirements are supplied by forage, along with 80 to 90 percent of the fiber (neutral detergent fiber) requirements. To successfully meet these requirements for high levels of milk production, high-quality forage must be a primary component of the diet, Schroeder says.
"Feeding excessively high levels of grain, even though that diet raises dietary net energy for lactation, will not match the performance of feeding high quality alfalfa with low to moderate grain levels," he explains. Research shows that cows fed high quality alfalfa hay (40 percent neutral detergent fiber) and 20 percent grain out-performed those cows fed low quality alfalfa hay (60 percent neutral detergent fiber) and 70 percent grain.
As forage quality declines, the amount of corn and soybean meal (or other appropriate energy and crude protein sources) in the ration must increase. The percentage of neutral detergent fiber from coarse roughage should be at least 75 percent of the ration.
The fundamental problem with feeding poor quality forage to dairy cows is the upper limit to intake in early lactation, Schroeder says. This occurs at about 32 to 34 percent dietary neutral detergent fiber or at 1.3 percent of bodyweight as neutral detergent fiber intake.
Above these levels, intake decreases, resulting in reduced milk production, poor body condition, and difficulty in rebreeding.
To cope with poor quality forages, producers can feed more grain, alter grain composition, feed supplemental fat, use high-fiber byproducts as starch replacements or forage extenders, feed more corn silage, and properly allocate forages based on quality, Schroeder says.
When increasing the amount of grain in the ration, the key is to avoid acidosis. Often, high-grain rations don't contain enough fiber to prevent this problem. When dietary neutral detergent fiber falls below 25 percent of ration dry matter or the forage is finely chopped, cows may experience reduced rumination, less saliva production, ruminal acidosis, low milk fat test, laminitis, chronic intake fluctuations, reduced milk production, and excessive weight loss during early lactation. To avoid these problems, limit grain intake to 7-8 pounds per feeding or 50 to 60 percent of ration dry matter.
When feeding high levels of grain, consider adding high-fiber, high-energy byproducts to the grain mix, such as ear corn, corn gluten feed, hominy, beet pulp or soyhulls. These feeds often reduce the incidence of acidosis and related off-feed problems. Many high fiber byproducts such as soyhulls, oat mill byproducts, cottonseed hulls, corn cobs and beet pulp can be used as forage extenders at 15 to 20 percent of ration dry matter. Maintain minimum effective fiber levels of 19 to 21 percent acid detergent fiber, 26 to 27 neutral detergent fiber, 75 percent of neutral detergent fiber from coarse roughage and 40 to 50 percent forage in total ration dry matter.
Two-thirds to three-quarters of the forage mix can easily be corn silage. Provide 5 to 7 pounds of hay or haylage per cow in the ration to keep cows from overfeeding on corn silage. When feeding corn silage, more protein supplements are needed, especially from soybean and animal sources. Use high-fiber, low-starch byproducts to stimulate rumination and reduce the potential for acidosis. Generally, adding a buffer and increasing feeding frequency will also promote better cow performance when feeding high corn silage diets.
Adding proper amounts of fat to diets containing low quality forage can boost the energy content and avoid the risk of acidosis from overfeeding grain. A good rule of thumb is that the pounds of fat in the ration should equal pounds of butterfat produced per hundredweight of milk.
The proper allocation of forages to the various classes of livestock can greatly improve the profitability of the feeding program. Make a forage inventory and allocation worksheet as part of your forage harvesting recordkeeping to organize and plan your forage feeding system.
For more information on feeding dairy cattle with limited high-quality forage, contact your county office of the NDSU Extension Service.