Swine Management Resources - PIC


A successful nutrition program needs not only an adequate diet formulation but also a high-quality, consistent, feed manufacturing process.

Particle size and feed form are discussed below. For more information regarding feed manufacturing download the “Feed manufacturing guidelines for PIC pigs” at

Particle size, depending on the phase of production, can be managed to maximize nutrient digestibility or to maximize longevity. Research has shown that for every 100 micron reduction in grain particle size feed efficiency improves 1.0 to 1.2% (Steinhart, 2011a). Practical particle size recommendations are generally coarser for boars, gilt development, and gestation and finer for lactation, nursery, and finishing. Grain particle size is influenced by testing methodology and therefore, consistent testing practices are a key for successful particle size management.

Boars, gilt development, and gestation
A primary focus for boars, gilt development, and gestation is to maximize longevity while achieving good nutrient digestibility. Previous research has shown that reduced or highly variable particle size can increase the incidence of stomach ulcers (Steinhart, 2011a) and potentially mortality (Goodband et al., 2002). Based on the combination of these factors it is important to follow the acceptable range of grain particle size presented in Table N1.



The focus of grain particle size for lactating sows is to maximize nutrient digestibility and, thus, milk output. Therefore, particle size should range from 500 to 600 microns on average. For every 100 micron reduction from 1200 to 400 microns, litter weight gain increased 1.3% (Wondra et al., 1995).

Typically, the grain particle size recommended for the nursery phase is 500 to 600 microns for mash diets and, approximately, 400 microns for pelleted diets. Grain particle sizes in meal diets greater than 600 microns will reduce the digestibility of nutrients and grain particle sizes smaller than 500 microns will decrease feed intake (Woodworth et al., 2015). The response to reducing particle size is similar for corn, sorghum, and wheat (Woodworth et al., 2015).

Finishing is the phase of production where nutrient digestibility needs to be maximized the most. Most feed mills will grind grain as fine as possible as long as feed can still flow in bins, feed lines, and feeders. Pelleting diets reduces feed flow ability problems. Woodworth et al. (2015) reviewed the literature and concluded that there is little benefit to reduce below 600 microns in high quality pelleted diets; however, lower particle size often is used to improve pellet quality.

Particle size and ground grain storage capability
As shown in Table N1, if the feed mill only has one bin for ground grain, a compromise between all phases would be 550 to 650 microns; however, it must be noted that feeding gestating sows with fine grain particle size can negatively impact sow mortality. Thus, two ground grain bins are recommended. Another approach is to limit the ground corn inclusion in the gestation diet by using other ingredients, such as DDGS that mitigate some of the negative effects of finely ground grain.

If the feed mill has two storage bins for ground grain, one bin could store grain at 450 to 600 microns for lactation, nursery, and finisher and the other at 750 to 900 microns for boars, gilt development, and gestating sows.

Evaluating particle size
For details about particle size testing methodology (time and whether to use an agitator or flow agent) please refer to Steinhart (2011b) and to Benz and Goodband (2015). For current methodology on particle size evaluation please visit

Pigs fed high-quality pellets will have improved feed efficiency. As pellet quality becomes poorer, the advantage in feed efficiency declines until no difference is found when the feed contains 50% fines or more at the feeder. Diet formulation has a major impact on pellet quality. Equally important is checking the pellet mill temperature, cooled pellet temperature, and pellet durability.

For nursery pigs, feeding pelleted diets in the first phase has been shown to increase feed intake and F/G by, approximately, 8% (Groesbeck et al., 2005) and to improve flow ability of the diets (DeRouchey et al., 2007). However, due to inclusion of high amounts of lactose and specialty protein sources, the inclusion of 2 to 3% fat is needed to facilitate the pelleting process. Diets with high inclusion of lactose sources are difficult to pellet, thus, care must be taken when using high inclusion rate (Leaver, 1988). Furthermore, in Phase 1 diets, pelleting temperatures lower than 170°F are typically used to avoid denaturing proteins from these diets that more typically contain higher levels of animal plasma and milk products (Steidinger et al., 2000). For pelleted diets, it is important to have less than 20% fines or otherwise the positive effects of pelleting are likely lost (Nemechek et al., 2012). A recent summary of experiments concluded that feed efficiency would increase 0.03 for each 10% increase in fines (De Jong, 2015).

PIC has performed a number of large scale trials comparing feed form of meal and pellets on feed efficiency. Trial results typically show that feeding high quality pellets to finishing pigs improve feed efficiency in all sire lines by, approximately, 6% (PIC internal data); however, the improvement of full-value pigs may be higher (1 to 3%) in meal diets for some lines.

Swine Management Resources - PIC