Using grasses to help keep transition cows’ rumens filled may be a low-cost, viable option for reducing the number of displaced abomasums (DAs) in a herd, suggests Randy Shaver, University of Wisconsin dairy scientist.
Some dairymen have followed a relatively new trend of adding wheat straw to dry-cow and prefresh diets and dry hay or even small amounts of straw for fresh cow groups “just to maintain adequate rumen fill and effective fiber and control rate of passage,” Shaver says.
“But, also, there is quite a bit of interest in using grasses in some of the rations or even mixed legume-grass stands. Grasses are a little higher in NDF (than alfalfa), so give more fiber. They also tend to process a little bit coarser than alfalfa and can stimulate rumination activity and increase rumen fill,” he explains.
Displaced abomasums usually appear in transition cows, when they’ve reduced their intake around calving time or have milk fever or ketosis.
“Just simply feeding a higher forage diet helps minimize a lot of these digestive disorders, including DAs, to the extent that we’re improving forage quality, fiber digestibility and increasing the amount of forage in the diet. That should help cows transition better into the high-group diet and minimize DAs, claw-feet problems, acidosis, those sorts of things,” the dairy scientist says.
Feeding straw also helps fill the rumen and increase intake. “But straw is very low in energy, which is okay for dry cows. As we get into peak lactation cows, you don’t necessarily want to be cutting the energy.
Shaver’s colleague, University of Wisconsin dairy scientist Dave Combs, has been studying the effect of adding high-quality grasses to the diets of high-producing milkers, replacing some corn silage and possibly a bit of alfalfa.
Combs has so far found that grasses tone down energy and boost fiber in hot corn silage-alfalfa rations that can cause lameness.
“The ability to incorporate high-quality grasses in rations may allow us to get more effective fiber and improve rumen health, maybe prevent DAs and acidosis without having to deal with wheat straw and its cost and some of the challenges of mixing,” Shaver says.
Cows may tend to sort out straw, so producers are adding water or finding other methods to keep them from doing so, he says. “If cows are not eating stems and are eating more concentrates, those individual cows may be more prone to DAs.”
Producers and researchers have also been proactive in trying to reduce the number of DAs in herds by maintaining adequate particle lengths, he adds.
“There’s been a lot of work done with chop length of forages, both hay crop and corn silage, and one of the main benefits of that is rumen health and, ultimately, minimizing DAs.”
Chopping corn silage at ¾” theoretical length of cut and haylage at 3/8-½” is recommended. “For preventing DAs, ensure that you allow for high intakes of dry matter, that there’s plenty of forage in the diet and that the forage is not too finely chopped so you have a high rumen fill during the transition period,” he recommends.