When hay macerators finally reach U.S. alfalfa fields, growers won't buy them just because they dry hay faster.

Maceration makes hay more digestible, according to a recent California study. The findings verify the results of earlier trials.

Macerators - machines that severely condition forage - have been under development for a number of years. They were expected to be available to U.S. growers by now, but none have been introduced. New Holland, however, is said to be testing one.

Studies have shown that macerated alfalfa dries faster than that cut with conventional equipment. The reduced drying time could help avoid rain damage, minimize yield losses from traffic damage and permit more timely irrigation, says University of California-Davis extension forage specialist Dan Putnam.

"These factors could increase yield by approximately 10%," he says.

In the California study, alfalfa was harvested July 31 at two maturity stages - 31 and 45 days after the previous cutting. The alfalfa was macerated with a mini-macerator on loan from the USDA-ARS Dairy Forage Research Center in Madison, WI.

The researchers used a fistulated cow to measure digestion. They placed alfalfa samples in nylon bags and inserted them into the rumen for varying periods. Then they measured the undigested material.

Digestion was the same for the 31- and 45-day alfalfas. But there were dramatic differences between macerated and non-macerated forage.

"With the macerated forage, approximately 34% of the plant dry matter was immediately soluble or released to the rumen," Putnam reports. "With the non-macerated samples, only 18% of the forage was immediately soluble."

The difference was evident throughout the digestive process. Even at 48 hours, there were significant differences.

"With maceration, cells are apparently ruptured, making more surface area available for immediate microbial degradation," says Putnam.

"There's a lag time associated with the digestion of the fiber in forage," explains Tim Kraus, a New Holland engineer who assisted with the study. "It takes eight to 10 hours before digestion actually begins. When the forage is macerated, the lag time is reduced. As soon as the cow swallows the forage, she can start digesting it and converting it into usable energy."

The mini-macerator conditioned the alfalfa more severely than would a field-size unit, cautions Putnam.

"The improvement in digestibility we measured should be viewed as the upper limit to what can be achieved through maceration, rather than the expected improvement," he states.

He says further studies are needed to measure maceration's impact on milk production.