Dairy Focus: Balance Rations to Avoid Rumen Problems

By J.W. Schroeder, Dairy Specialist

NDSU Extension Service

Corn silage is a wonderful feed for dairy cattle.

It is a lot of work, but once it is in the yard and put up properly, nutritionists love to include corn silage in a ration for energy and more milk production.

But, as with all good things, the amount of corn silage should be balanced in the ration carefully to prevent health problems such as lameness and acidosis.

This year, going overboard may be easy. This is especially true with the inclination to step up the rate of feed-out of the 2009 corn silage harvest to reduce spoilage as spring nears.

While I have recommended increasing feed-out to avoid losing silage unnecessarily due to spoilage, one fact remains: The health of the cow should have first priority.

This is one of those scenarios where trying to do the right thing for the farm feed budget could compromise cow health. Why? Because rations high in silage also can be low in fiber. If you are pushing more corn silage into the ration and less hay, be careful because acidosis could become a problem.

Several common factors lead to acidosis in dairy cattle, according to Limin Kung, University of Delaware dairy nutritionist. They include:

• Diets too high in fermentable carbohydrates
• Too high concentrate-to-forage ratios
• Switching from high-forage to high-concentrate rations too fast
• Switching from silage to high levels of green-chop forage too fast
• Low fiber content in diets
• Diets composed of very wet and highly fermented feeds
• Too finely chopped forage
• Overmixed total mixed rations, resulting in excess particle size reduction
• Mycotoxins

Not every issue can be blamed on the poor harvesting weather of 2009, but overfeeding corn silage could become a big factor this year. How can you tell if your cows have acidosis? Common symptoms include:

• Low milk fat test (less than 3 percent to 3.3 percent in Holsteins)
• Sore hooves; laminitis
• Cycling feed intake
• Diarrhea
• Liver abscesses
• Low rumen pH (less than 5.8) in 30 percent to 50 percent of animals tested
• Limited cud chewing

You can read more on feeding to minimize acidosis and laminitis in dairy cattle on eXtension at http://www.extension.org/pages/Feeding_to_Minimize_Acidosis_and_Laminitis_in_Dairy_Cattle.

NDSU Agriculture Communication