Remember how the rumen functions, says nutritionist Many dairy producers have gotten so caught up in RFV, TLC, NFC, etc., that they forget to think about the cow's rumen and the kinds of feeds that help it function efficiently.

That's according to nutritionist Bill Nelson, president of Nelson Dairy Consultants, Lakeville, MN.

"We are doing everything to provide a high-energy diet to the cows and in the process we forget that they're still cows," says Nelson.

Since ruminants have the ability to get energy from fiber, cows and forages are made for each other, he says.

"Forages are the base of an efficient cow diet," says Nelson. "If you don't have good, digestible forages, none of the other stuff matters."

Long fiber particles form the rumen raft, which keeps the rumen expanded, maximizing its volume. Volume is important, because the larger the rumen, the longer period of time particles stay there before passing to the lower intestine where fiber is not digested. Fiber is digested slowly, so the longer fiber stays in the rumen, the more digested it gets, and the higher the real energy value of the forage.

The rumen raft, which expands the rumen to its maximum volume, stimulates and helps maintain the tone of smooth muscles that surround the stomach. When the rumen is full, these muscles are forced to regularly contract, mixing the rumen contents. That increases digestion by continually exposing rumen bugs to new feed particles.

The rumen raft also forces the cow to chew her cud regularly. Cud chewing reduces the size of raft particles so they can pass out of the orifice leading to the omasum and lower gut.

Nelson says the feed industry is the heart of the problem.

"We tend to think that additives are the solution to all of our problems," he says. "The more additives there are in a ration, the less room there is for forages.

"If we were able to improve forage digestibility, we could eliminate all additives from the diet and just leave forages. The additives not only include fats and other byproducts, but grains as well."

He lists three things hay growers can do to improve digestibility:

- Pay attention to plant genetics. Choose forage species and varieties with high fiber digestibility traits. Growers are so concerned about yield that they often forget about fiber digestibility, he says.

- Cut early for maximum fiber digestibility.

- Understand how the environment affects digestibility. For example, alfalfa is more digestible when grown under wet conditions than when moisture is lacking, says Nelson.