The particle size of a pig diet can have a big impact on feed efficiency, and now is a good time to eek out as much as you can from every bite.

Bob Goodband, KansasStateUniversity swine specialist, recommends that particle size be held around 700 microns, with an optimal range of 650 to 750 microns, as larger particle sizes result in poor feed efficiency. “For every 100 microns that particle size exceeds the recommend range, the cost for lost feed efficiency will be about 65 cents per pig,” Goodband says.

For example, suppose you haven’t checked particle size recently, and it has crept up to 1,000 microns. If you reduce it back to 700 microns, you will save almost $2 for every finishing pig marketed, he notes.

But don’t drop below the 650 micron mark. “Studies have shown diminishing returns on smaller particle size, which can increase milling costs due to higher energy input costs” Goodband cautions. It also can create bridging in feeders and bins; and pigs can face a greater susceptibility to gastric ulcers.

As for equipment, Goodband says both hammer mills and roller mills have their advantages and disadvantages. Particle size and shape tend to be more uniform with a roller mill, which helps ground feed flow well.

Regardless of the mill, Goodband recommends regular maintenance such as changing hammer-mill screens or turning hammers. Adjustments to the grinding surfaces and mill rollers should be part of routine service and maintenance.

“If you use toll-milled feed, ask the mill for regular particle size analysis as part of its quality-control program,” he adds.

Check laboratories in your area and determine which ones offer particle size analysis. You should be able to have diets analyzed for about $10 per sample — a wise investment if it reduces energy use, cuts milling costs and boosts your pigs’ feed conversion.