Rojas, O. J. and H. H. Stein. 2014. Effects of reducing the particle size of corn on growth performance of weanling pigs. J. Anim. Sci. 92(Suppl. 2):158 (Abstr.) Link to abstract (.pdf)

Rojas, O. J. and H. H. Stein. 2013. Reducing feed particle size may enhance performance. Page 12 in National Hog Farmer, December 15, 2013. Link to full text

Grinding of feedstuffs to small particle sizes is a low-cost way to increase their energy and nutrient digestibility. Currently, nutritionists recommend feeding corn ground to an average particle size of 650 to 700 µm. However, it may be advisable to formulate diets containing corn ground to smaller particle sizes due to the greater metabolizable energy (ME) values of these diets. A previous experiment conducted by Rojas and Stein at the University of Illinois demonstrated that when diets are formulated to contain the same amount of metabolizable energy, feeding diets containing corn ground to different sizes to weanling pigs did not have a negative effect on growth performance.

An experiment was conducted to test the hypothesis that when diets are not adjusted to contain equivalent amounts of metabolizable energy, weanling pigs fed diets containing corn ground to smaller particles sizes will have an improved gain to feed ratio relative to pigs fed corn containing corn ground to larger particle sizes.

The metabolizable energy content of corn ground to smaller particle sizes is greater than that of corn ground to larger particle sizes, because the reduced particle size provides more surface area for digestive enzymes to act on. This results in more starch being digested in the small intestine with a subsequent absorption of glucose.

Currently, nutritionists recommend feeding corn ground to an average particle size of 650 to 700 µm. However, it may be advisable to formulate diets containing corn ground to smaller particle sizes due to the greater ME in these diets. If diets are formulated to a constant ME, the inclusion of added fat can be reduced if corn ground to a smaller particle size is used.

In a previous experiment, growth performance did not differ among growing-finishing pigs (average initial body weight: 32 kg) fed diets containing corn ground to particle sizes ranging from 339 to 865 µm if diets were formulated to the same ME by reducing the concentration of added fat as corn particle size was reduced. The experiment discussed in this report was conducted to test the hypothesis that added fat can be reduced in diets fed to weanling pigs if corn ground to a smaller particle size is used.

Research has shown that grinding cereal grains in diets fed to pigs into smaller particle sizes improves growth performance. Feed ground to smaller particle sizes has more surface area on which digestive enzymes can work, so digestibility of energy and nutrients that are enzymatically digested may also be improved. Previous research at the University of Illinois indicated that particle size had no effect on the digestibility of phosphorus, but that decreasing particle size increased energy digestibility in corn in the range of 338.5 μm to 864.5 μm.

However, it is not known if reduced particle size also increases amino acid digestibility. Therefore, an experiment was conducted to determine the standardized ileal digestibility (SID) of amino acids in corn that was ground to different particle sizes and fed to growing pigs.

Stein, H. H., D. Y. Kil, and J. A. Roth. 2012. Strategies for managing weanling pigs fed no antibiotic growth promoters. Swine Focus #003. Link to full text (.pdf)