The particle size of a pig diet can have a huge economic impact on production costs says Kansas State University Research and Extension swine specialist Bob Goodband. He recommends that particle size be maintained at approximately 700 microns with an optimal range of 650 to 750 microns, because larger particle sizes result in poor feed efficiency.

As particle size is reduced, the digestibility of the diet can improve, however, there are tradeoffs. Smaller particle sizes increase the cost of milling and grinding feed grains as energy input costs are higher. There also can be storage problems with bridging in feeders and bins; also, pigs fed these diets can have a greater susceptibility to gastric ulcers.

"For every 100 microns that particle size is above the recommend range, the resulting cost for lost feed efficiency will be about 65 cents per pig. For example, suppose you haven’t checked your particle size recently, and it has crept up to 1,000 microns. If you reduce that particle size to 700 microns, that will save you almost $2 for every finishing pig marketed," says Goodband.

Goodband recommends that producers regularly carry out routine maintenance to feed processing equipment, such as changing hammer mill screens or turning hammers. Livestock producers and nutritionists can also have the particle size of their diets analyzed independently for around $10 per sample. This is a wise investment if it enables a reduction in energy use, lower milling costs and better feed conversion.