Hello, everyone. My name is Su A Lee from the Stein Monogastric Nutrition Laboratory at the University of Illinois. 
I will be discussing the effects of pelleting and reducing particle size of corn on ileal digestibility of starch and amino acids in diets fed to pigs.
This work was presented in 2023 ASAS Midwest Meeting.
Pelleting is a process of compacting and shaping feed ingredients into small pellets or granules.
This thus helps in the ease of handling, transport, storage, and consumption of animals.
Pelleting can potentially increase the digestibility of starch and amino acids in pigs as well. 
The pelleting process involves heat and pressure, which can improve the digestibility of starch and amino acids in feed ingredients by breaking down protein structures, reducing anti-nutritional factors, and gelatinizing starch. 
Because pelleting also increases palatability of pigs and digestibility of nutrients, the growth performance of pigs is improved as well. 
However, because the process, again, involves heat and pressure, this may induce the heat damage of amino acids. Lastly, the diets cost more because this is an extra process.
Reducing particle sizes of grains increases the surface area available for enzymatic activity, and thus leads to increased digestibility of nutrients and also growth performance of pigs.
However, because finely ground diets can generate dust and have negative impact on gut health, reducing particle size can cause health problem pigs. Like pelleting, reducing particle size increases the overall cost of feed production because this requires additional grinding or processing steps.
This experiment was conducted to test the hypothesis that particle size reduction and pelleting, separately or in combination, increase ileal digestibility of starch and amino acids in corn-soybean meal diets fed to growing pigs
In this experiment, diets were arranged with 2 by 3 factorial and all diets contained corn and soybean meal.
the first factor was the diet form, meal or pelleted
And the second factor was particle size of corn. One batch of yellow dent corn was prepared and ground into 3 different particle sizes from 700, 500, to 300 microns.
Pigs were fed ad libitum and had free access to water throughout the experiment. 
A total of 7 pigs with approximately 59 kg body weigh were used and all pigs were surgically installed with a T-cannula in the distal ileum.
A nitrogen-free diet was also used to determine the basal endogenous losses of amino acids. Therefore, we used 7 diets in this experiment and all diets contained titanium dioxide as an index.
Pigs were allotted to a 7 by 7 Latin square design with 7 treatments and 7 periods to have a total of 7 replicates per diet. 
Ileal digesta were collected for 2 days after 5 days of adaptation. 
The ileal digesta were immediately stored at negative 20 to prevent microbial fermentation of amino acids. 
Using analyzed titanium, dry matter, starch, and AA in diets and ileal digesta, the apparent ileal digestibility, AID, was calculated.
The standardized ileal digestibility, SID, of AA was calculated by correcting the AID of AA for the basal endogenous losses of AA.
The statistical model included diet as the fixed variable and period and pig as random variables.
Contrast coefficients were used to compare the two diet forms, linear effects of reducing particle size, and the interaction between diet form and particle size.
Moving on to the results, let me set up the slides first.
The yellow represents diets in meal form and orange represents diets in pelleted form. 
Within each diet form, there are 3 different particle sizes of corn that are 700 all the way down to 300 microns.
There were no interactions between diet form and particle size of corn and the effects of pelleting or reducing particle size were not observed for the AID of dry matter.
With no changes found in the AID of dry matter, there was no interaction between pelleting and reducing particle size on the AID of starch.
Regardless of diet form, reducing particle size linearly increased the AID of starch and regardless of particle size of corn, pelleting increased the AID of starch in diets.
The observation clearly indicates that pelleting increases starch digestibility by increasing starch gelatinization and that reducing particle size increases starch digestibility by increasing surface area of particles.
For indispensable amino acids, the SID of Lys was linearly increased by reducing particle size, but the effect was greater in pelleted diets compared with meal diets. 
Pelleting increased the SID of Lys, even though Lys is one of the most susceptible amino acids to heat. This indicates that under the condition of this experiment, the heat damage by pelleting was minimized.
The SID of Met was linearly increased by reducing particle size, but the effect was greater in pelleted diets compared with meal diets. 
Regardless of particle size of corn, pelleting increased the SID of Met.
Similar was observed for Thr. The SID of Thr was linearly increased by reducing particle size, but the effect was greater in pelleted diets compared with meal diets. Pelleting increased the SID of Thr in diets containing 3 different particle sizes of corn.
There was no interaction between pelleting and particle size and there was no particle size effect on the SID of Try. However, the SID of Try was increased when diets were pelleted. 
There was no interaction between pelleting and reducing particle size on the SID of total amino acids.
Regardless of diet form, reducing particle size linearly increased the SID of total amino acids and regardless of particle size of corn, pelleting increased the SID of total amino acids in diets.
The observation indicates that pelleting may break down protein structures and remove anti-nutritional factors and that reducing particle size may increase the surface area of proteins to be digested and absorbed.
In conclusion, we found that there was no interaction between pelleting and reducing particle size on the ileal digestibility of starch, Arg, His, Isoleucine, Try, and total amino acids.
The interactions were found in the SID of Lys, Leu, Met, Phe, Thr, and Val and it was observed that the particle size effects were greater in pelleted diets.
Lastly, both diet form and particle size affect the ileal digestibility of starch and some amino acids.  
I would like to acknowledge everyone from Dr. Stein’s lab. And if you want to learn about the research we are conducting in the Stein Monogastric Nutrition Laboratory, please visit our website at nutrition.ansci.illinois.edu, or search “Stein” and “pig” on google. Thank you for listening.