Guidelines for Particle Size on Swine Operations
Particle size is an area where producers can significantly improve feed efficiency and lower feed cost per kg of gain. Research at Kansas State University has indicated that, for corn-based diets ranging in particle size from 1200 to 400 microns, there is a 1 to 1.5% improvement in feed efficiency for every 100 micron reduction in average particle size.
What is the "correct" particle size?
Current research suggests that the optimum particle size for pigs is 700-800 microns (0.7-0.8 mm). It is too expensive to grind any finer than this since the time and energy inputs often outweigh any improvement in feed efficiency.
Feed that is finer than 700 microns will produce ulcers in pigs very quickly. Research at the University of Guelph has shown that feed with a particle size of 550 microns produced ulcers in 90% of pigs in only 2 weeks; after 4 weeks the first pig died from bleeding ulcers.
As a rule, swine diets tend to be too coarse rather than too fine.
Particle size distribution
It is important to consider the distribution in particle size, not just the average. Obviously a consistent diet, with a narrow distribution would be ideal. Assess the level of extremes in the sample. Large percentages of dust (particles smaller than 150 microns) and very coarse particles (particles greater than 1200 microns) should be minimized.
Unfortunately, there has not been a lot of research into the appropriate distribution of particle size so there are no useful numeric guidelines for assessing what amount of variation is appropriate in your sample.
Maintaining particle size on-farm
The best, and really only, way to determine the appropriate screen size to use is to have samples analysed for particle size. Based on processing volumes, Kansas State University recommends that particle size should be checked every 500 to 700 tonnes of feed processed.
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