Adapting roller mill kernel processors to pull-type forage harvesters suddenly is a hot topic, helped along by last year's high grain prices. The endless quest for more efficient milk production has engineers reconfiguring the technology, previously available only on larger self-propelled harvesters in Europe and North America. Units are being adapted for the lower-cost pull-type harvesters prevalent on mid-sized dairies across the United States and Canada.

Gehl Company and Canadian-based Dion Machinery Ltd. have tested pull-type prototypes during the past two years, and both companies plan to unveil their units for the 1998 crop year. Neither company has yet announced particular models or prices for the units. See your dealer.

More milk. A University of Wisconsin study with roller mill processors used on corn silage at the silo have shown that better pulverization of kernels and forage improves digestibility, decreases grain in the manure, and can boost milk production by 3.8% - or nearly 3 lbs. per day. According to the study, assuming you have a 20,000-lb./year cow and a milk price of $14.00/cwt., a 3.8% increase could mean an additional $106/cow/year to be used to offset the additional cost of capital and energy needed for processing silage.

In the Wisconsin study, the 48-in. rollers on the prototype at the silo, supplied by Automatic Equipment Manufacturing Company, Pender, NE, were set for minimum clearance and maximum grinding effect, damaging virtually all the kernels and reducing the average particle size.

"I think roller mill kernel processing has the most potential for corn that's on the mature side, where the breakup of the kernels, as well as fiber, is important," says Dick Straub, chairman, Department of Biological Systems Engineering, University of Wisconsin-Madison. "Some of the benefit that we see from processed corn comes not only from the disruption of the kernels but from the disruption of the forage as well, because we know that with alfalfa we get more energy out of the crop if we macerate it severely before it goes to the silo."

Roller mill processors on self-propelled choppers streamline the later process of loading the silo. It's the next affordable step for smaller forage operations.

First prototype. Researchers at Laval and McGill universities in Quebec were the first to experiment in 1995 with a pull-type-mounted two-roll processor prototype using a Dion chopper. The blower, normally located directly behind and parallel to the cutterhead, was moved upward and to the rear to make room for the two grooved processing rolls placed parallel to each other between the cutterhead and the blower above.

In 1995 tests, power requirements and real length of cut were measured for alfalfa and corn silage. With a tight clearance, processed alfalfa required 30% more power. Corn, with a 6-mm (1/4-in.) clearance between rollers, required 7% more power. Average processed particle length at that clearance was 15% shorter.

Only 3% of the processed, chopped kernels remained undamaged, compared to 20% without processing. Of processed kernels, 4% were cracked (19% for unprocessed kernels) and 93% (vs. 61% unprocessed) were broken.

In fact, about a quarter of the original grain was pulverized. This starch-rich powder is expected to be more rapidly digested than either whole or cracked corn.

Ready for 1998. "When we started roller mill processors with John Deere and New Holland in 1979, this was strictly a European market, where self-propelled harvesters are the norm. Roller mill processors on pull-types are just in their infancy now," says Denny Fillipi of Automatic, which has been fitting roller mill processing prototypes to Gehl's three-row pull-type harvesters for tests during the 1996 and 1997 seasons.

"They needed something to compete against the high cost of the self-propelled units, and our tests have found pull-types to be very efficient," says Fillipi. "It looks like a full-go into production for 1998."