Hi. My name is Oscar Rojas, and I'm a former PhD student in the Hans Stein
Monogastric Nutrition Laboratory. In today's podcast, I'm going to talk to you
about the effects of pelleting and extrusion on energy digestibility in pig
diets containing different level of fiber for growing pigs.

This is the outline of this presentation. I will start with an introduction
about different greed ingredients that are used in diets fed to pigs, as well as
some feed processing technologies that are used in this field. Then, we will
move into the materials and methods, results, and we'll finish up this
presentation with some conclusions and the implications of this research.

If you have seen my latest podcast, probably you are familiar with this slide.
But this slide represents very well how a production system works, and how it
can be modified with external factors such as feed processing technologies.
Let's begin with the input, that in this case is represented by the diet. As a
nutritionist, we control this factor. And therefore, we can decide what type of
ingredients need to be included in our diets and in which concentrations. The
output of this system in this case, are the feces. During the manufacture of
diets, sometimes there is the opportunity to use different type of feed
technologies such as extrusion, and pelleting. And for example, if we fail to
use any of those technologies, or if we include an ingredient at the wrong
concentration in our diets, we will expect to see an increase in the excretion
of nutrients in the feces. And this means that we are going to waste money, as
well as contaminate the environment with those nutrients.

We have some advantages when we use feed technologies in our diets. Some of them
are: increases availability of nutrients, decreases excretion of nutrients, may
increase growth performance, and may observe increased gelatinization.

Likewise, we have some disadvantages, like processing, it will add costs in our
production system; excess of heat will reduce the digestibility and the
concentration of lysine for the formation of Maillard reactions, and you could
also get retrogradation of starch. And this means that we generate resistant
starch that won't be digested in the small intestine, and therefore will be
fermented in the large intestine.

In this slide, we could observe the concentration of neutral detergent fiber, or
NDF, in different ingredients. But the point here is that when we move from
conventional ingredients such as corn and soybean meal to alternative
ingredients such as DDGS and soybean hulls, we usually observe an increase in
fiber in our diets. And the problem with increasing the concentration in fiber
is the reduction in the total tract energy digestibility as well as a reduction
in the standardized ileal digestibility of crude protein and amino acids.

So the objective for this experiment was to determine the effect of different
processing techniques on energy and nutrient digestibility of diets containing
different levels of fiber fed to pigs.

In this experiment, we used 24 barrows within initial body weight of 26.5 kg ±
1.5 kg in four periods. This experiment was set up as a split block design with
three levels of fiber – low, medium, and high – and four types of processing –
meal, pelleting, extrusion, and extrusion and pelleting.

Pigs were adapted to the level of the fiber in the diets for 14 days prior to
the start of the experiment. Pig was the experimental unit for all the stats
analysis, and the alpha level was used at 0.05.

Each period lasted 14 days. The first five days were considered the adaptation
period. The next 5 days were considered the collection of fecals and urine
samples, and the last two days was used to collect ileal samples.

As I mentioned before, we had three levels of fiber: low, medium, and high. Low
were the diets containing 8.6% of NDF, medium 14.5%, and high 24.6% of NDF. A
low fiber diet was considered when used corn and soybean meal. The medium level
of fiber was when we added 15% of DDGS on top of the corn and soybean meal, and
the high fiber diets was when we included corn, soybean meal, DDGS, and soybean
hulls.

In this slide, we can observe how we processed the diets. Let's take as an
example the low fiber diet: corn and soybean meal. We mixed a diet and we
considered that the meal treatment.

Then, we used that diet and we pelleted at 85 degrees Celsius. That was
considered the pelleted diet.

Now, we took the meal diet and we extruded at 115 degrees Celsius, and that was
considered the extruded diet.

And when we took again the meal diet, but we extruded and then pelleted, we
called that the last treatment: the extruded and pelleted diet.

This slide is just to show you a summary of how this experiment was conducted.
We have three levels of fiber: low, medium and high; four treatments within
levels of  fiber: meal, pelleting, extrusion, and extrusion and pelleting; and
we have eight pigs within levels of fiber for a total of 24 pigs for the whole
experiment.

Now, let's move on into the results. Since we have a factorial arrangement in
this experiment, we tested our variables for the main effects -- effects of
fiber, and the effects of processing -- and the interaction between those two.
And in this case, we observed that for variables such as starch digestibility,
amino acid digestibility and energy digestibility, no interactions were observed
between levels of fiber and type of processing. So I will just present the
results for the feed processing. However, in the case of energy concentration,
there was an interaction between the two main factors.

In this slide, we observe the apparent ileal digestibility of starch. The
digestibility of starch was improved when diets were pelleted, extruded, or when
the combination of both technologies was used compared with the meal diet. The
increase in apparent ileal digestibility of starch that was observed in the
diets that were extruded, pelleted, or combined with both technologies indicates
that the starch in corn will become more digestible if we use those
technologies. The increase in starch digestibility will likely have a positive
impact on energy utilization from the pigs.

In this slide, we observe the apparent ileal digestibility of lysine. Apparent
ileal digestibility of lysine was greater for extruded diets compared with the
pelleting and the meal diet. However, there were no difference between the
extruded diet and the extruded and pelleting diets.

When we observe the apparent ileal digestibility of threonine, we observe the
same pattern as the previous amino acid. Extrusion will increase the apparent
ileal digestibility comparing with the meal diet and the pelleted diet. But here
were no difference between the extruded diet and the extruded and pelleting
treatment.

So in summary, we can say that for all indispensable amino acids, the apparent
ileal digestibility was greater for pelleted, extruded, or the combination of
both systems compared with the meal diets.

In this slide, we observe the apparent total tract digestibility of gross
energy. We observe here that pigs that were fed the diet that was pelleted, or
extruded and pelleted, had greater digestibility of gross energy comparing with
the meal diet. But this was not the case when we compared these two treatments
with the extruded diet.

In this slide, we have the ME concentration on dry matter basis. This slide, we
observe that we have an interaction between fiber and type of processing. The
blue bars represent the low fiber diet, the orange bars represent the medium
fiber diets, and the red bars represent the high fiber diets. and in this slide,
I would like to point out three important points. The first point is that as we
increase the levels of fiber in the diets, we observe that here is a reduction
in the energy concentration in those diets. The second point is that the
extrusion increased the energy concentration in high and medium fiber diets, but
this was not the case for the low fiber diets compering with the meal diet. And
the last point that I would like to mention is that there was a greater increase
in the ME concentration in high fiber diets comparing with the low fiber diets.

So the overall conclusions for this experiment is that ileal digestibility of
amino acids and starch were improved by pelleting, extrusion, or the combination
of both technologies.

Also, extrusion improved the energy value to a greater extent in high fiber
diets than in low fiber diets.

And the implication of this experiment is that extrusion or combination of
extrusion and pelleting may ameliorate the reduction of energy observed when
high fiber ingredients such as soybean hulls are included in our diets.

And with this, I would like to acknowledge the sponsors for this experiment,
both Buhler Group and the National Pork Board.

Thank you for your attention. And if you enjoyed this podcast and you would like
to hear more about the exciting topics in swine nutrition, please visit our
website at nutrition.ansci.illinois.edu. Thank you.