Enhancing digestibility of corn fed to pigs at two stages of growth through management of particle size using a hammermill or a roller mill

Abstract

The experimental objective was to determine the role of mean particle size (PS), grinding method, and body weight (BW) category on nutrient, fiber, and energy digestibility of corn. A total of 48 barrows were housed in individual pens and randomly assigned to one of six dietary treatments for 11 d at two BW categories (55 kg and 110 kg). The six treatments consisted of corn ground at three different targeted mean PSs (300, 500, and 700 µm) using either a roller mill or a hammermill. Fecal samples were collected for the last 3 d of each feeding period. Titanium dioxide was used as an indigestible marker. Digestibility data were analyzed as a linear mixed model using the MIXED procedure of SAS. Finishing pigs had greater apparent total tract digestibility (ATTD) of dry matter (DM), gross energy (GE), and N than growing pigs (P = 0.02, P = 0.01, and P <0.01, respectively). The ATTD of DM, GE, and N was similar in pigs fed hammermilled corn across all PS treatments. However, in roller-milled corn, they increased as PS was reduced (P < 0.05). The ATTD of acid-hydrolyzed ether extract (AEE) in growing pigs was similar between corn ground at 700 and 500 µm, but it was increased by further reducing PS to 300 µm (P < 0.05). In finishing pigs, the ATTD of AEE increased as mean PS decreased from 700 to 300 µm (P < 0.05). The ATTD of AEE was similar in hammermilled corn at all three PS treatments. On the other hand, the ATTD of AEE was similar in corn ground in a roller mill to 700 and 500 µm, but it increased when PS was reduced to 300 µm (P < 0.05). In conclusion, reducing PS of corn with a roller mill increased digestibility of energy and nutrients, but there was less effect using a hammermill. It is possible that differences in SD, distribution, chemical composition, and the shape of the particles resulting from the two grinding processes help to explain the different response.

Effects of grinding method and particle size of wheat grain on energy and nutrient digestibility in growing and finishing pigs

“…2 ). The observed PS parameters were different than those observed in a similar experiment investigating PS in corn grain ( Acosta et al, 2019 ); in that study, the hammermill resulted in a greater SD of PS when compared with the roller mill. The absence of any difference between GM may be noteworthy since increased variation in PS can affect energy digestibility ( Patience et al, 2011 ).…”

Can the digestibility of corn distillers dried grains with solubles fed to pigs at two stages of growth be enhanced through management of particle size using a hammermill or a roller mill?

“…At the feed mill, corn DDGS may be ground to a smaller PS; depending on available equipment, an HM or RM may be used. The purpose of such grinding is to increase feeding value by enhancing the digestibility of energy and nutrients ( Htoo et al, 2008 ; Acosta et al, 2020a , 2020b ). The results of this experiment confirmed that reducing the PS of corn DDGS with either an HM or an RM (from 670 to 450 μm) increased the digestibility of DM, GE, and AEE and tended to increase the digestibility of N. This improvement is presumably a consequence of increasing the surface area ( Stark, 2012 ), allowing for easier access by enzymes secreted within the gastrointestinal tract of the pig.…”

“…Images depicting the topography and PS of the experimental diets were captured using field emission scanning electron microscopy (Roy J. Carver High-Resolution Microscopy Facility, Iowa State University, Ames, IA) following the procedures previously described by Acosta et al (2020a , 2020b ).…”

“…First, it is necessary to clarify if grinding methods (GMs), such as HM or roller mill (RM), are equally effective. The digestibility of corn and wheat has been reported to differ by using an HM compared with an RM ( Acosta et al, 2020a , 2020b ). Second, digestion improves as animals grow ( Noblet and Henry, 1993 ; Acosta et al, 2020b ).…”

“…The digestibility of corn and wheat has been reported to differ by using an HM compared with an RM ( Acosta et al, 2020a , 2020b ). Second, digestion improves as animals grow ( Noblet and Henry, 1993 ; Acosta et al, 2020b ). This has been attributed to a more developed gastrointestinal tract with greater digestive capacity.…”