Slide 1
Good afternoon. I'm Hans H. Stein, and I'm a professor at the University 
of Illinois at Urbana-Champaign. And I would like to talk to you today 
about how to use soybean products in diets fed to swine.

Slide 2
First of all, let's look at the composition of soybeans and soybean 
meal.

Slide 3
If you look at soybeans first, we'll see we have moisture in them, about 
10%. We have minerals or ash, that is 5%. We have fat, that's 19%. 
Protein is 35%. And then we have carbohydrates; and we divide the 
carbohydrates into sugar, oligosaccharides and fiber. And the sugar and 
oligosaccharides combined are about 16%, whereas the fiber is about 15%. 
Now, the fiber in this case is not an analyzed value; it's actually a 
calculated value, and it is the difference between the concentrations of 
all the other nutrients and 100%. So, it's a number that is calculated 
by difference. If we were to analyze, say, NDF in soybeans we would get 
a number that is a little but lower than what we have here, maybe 9 or 
10%.

But this is the composition of soybeans. We don't feed a lot of soybeans 
to pigs. Most of the soybeans we feed, we actually feed in the form of 
soybean meal, and the soybean meal is either dehulled or not dehulled. 
And we can see in the middle column here and in the right column, if we 
assume the moisture is still 10%, which means the dry matter is about 
90% in these soybean meals, that means the concentration of minerals 
will go up to about 6%. But the fat is down to about 1.5% in both 
dehulled and nondehulled soybean meal. And the reason is that soybean 
meal is produced by defatting the soybeans. So, of the 19% fat we had to 
begin with in the soybeans, we only have 1.5% approximately left after 
the soybeans have been defatted. Because of the reduction in fat, 
everything else is increased. So protein goes up from about 35% to 47.5% 
in soybean meal dehulled, and 43.2% on average in nondehulled soybean 
meal.

The sugar and oligosaccharides go up a little but from 16 to 18.5 or 
17.5 and fiber will stay about the same if we have dehulled soybean 
meal. We can see here that's calculated at 16.5%, however, if the beans 
are not dehulled then the fiber would be about 21.8%. And again, 
remember these are not analyzed values for fiber; these are calculated 
values.

Slide 4
If we look at the sugar and oligosaccharides, we'll see we have about 
four percent free sugars in soybean meal. Sucrose, which is a 
disaccharide, accounts for about 8%. It can be a little bit less than 
that or a bit more than that but on average we have about 8% sucrose in 
soybean meal. And then we have what we call galacto-oligosaccharides or 
alpha-galactosides and that's about 6.5% on average. It can vary among 
different varieties -- they could be a little bit less than 6.5%, or it 
can also be a little bit more than 6.5%. And the 
galacto-oligosaccharides consist of three different oligosaccharides. 
One is called raffinose, one is called stachyose, and one is called 
verbascose.

And, you can see stachyose is the one that has the greatest 
concentration among these three oligosaccharides. And stachyose is 
easily fermented in older pigs however pigs that are relatively young, 
that means the first couple of weeks after weaning, they don't handle 
this stachyose very well and they actually can get some diarrhea and 
they have a low digestibility of stachyose and therefore stachyose has a 
negative impact on growth performance of pigs right after weaning. It is 
therefore relatively common to not include a lot of soybean meal in 
diets fed to newly weaned pigs. Most newly weaned pigs get diets that 
are containing only 10-15% soybean more and the reason is pigs don't 
tolerate this stachyose very well.

Slide 5
The main reason for including soybean meal in diets fed to pigs is to 
provide amino acids in the diets. So let's talk a little bit about the 
amino acids we have in soybean meal.

Slide 6
We can see here in the blue bars we have the concentration of amino 
acids in nondehulled soybean meal and in the orange bars we have the 
concentration in dehulled soybean meal. And we will see here among the 
most limiting indispensable amino acids, we have slightly greater 
concentrations of amino acids in the dehulled soybean meal than the 
nondehulled soybean meal and the reason simply is that we have more 
protein in the dehulled soybean meal then we have in the nondehulled 
soybean meal.

Slide 7
However, more than the concentration of amino acids, the quality of the 
protein is also important. And when we look at this slide, we have 
protein concentration for soybean meal here, we have it for corn and we 
have it for distiller's dried grains with solubles. So, these three 
ingredients, they contain 47.5, 8.3, and 27.5% crude protein, 
respectively. If we calculate the concentration of each amino acid as a 
percentage of the total crude protein then we'll get a measure for the 
quality of this crude protein and not all proteins have the same quality 
when they are fed to pigs. And we will see here that lysine has a 
concentration of 6.35% in soybean meal but only 3.13% in corn and 2.84% 
percent in DDGS. For methionine, the picture is the opposite; we have a 
greater concentration in corn and DDGS than we have in soybean meal. 
Threonine is relatively close for all three ingredients but when we come 
to tryptophan, which is oftentimes a second limiting amino acid in diets 
fed to pigs, we can see again that the concentration in soybean meal is 
much greater than it is in the protein that is present in corn and in 
distillers dried grains. For isoleucine we also have a greater 
concentration in soybean meal than in corn and DDGS, whereas for valine 
it's about the same in all the ingredients. What this tells us is that 
soybean meal is an excellent source of lysine, and tryptophan, and 
isoleucine and particularly when we compare it to corn and distillers 
dried grains or any other corn protein for that matter. And one of the 
characteristics of corn proteins is that they are always low in lysine 
and low in tryptophan. So, by adding soybean meal to corn-based diets we 
make up for those deficiencies and that's why corn and soybean meal 
complement each other. And we also note here that soybean meal is 
relatively low in methionine but corn and DDGS are relatively high in 
methionine. Also in that case do the two sources of protein complement 
each other.

Slide 8
You can also express the amino acids in soybean meal relative to the 
requirement of the pig. And in the column here in the middle, we have 
the requirement of the pig for each amino acid expressed as percentage 
of the requirement for lysine. And for methionine, the pig have a 
requirement of 30% of the lysine content, for methionine+cysteine it's 
60%, for tryptophan it's 18% and so forth. And if we do the same 
calculation for the amino acids in soybean meal, we can see here that 
methionine and methionine+cysteine are 22 and 47% respectively of the 
concentration of lysine. And we will see for both of these two values 
they are less than the requirement for the pig. So again, that shows 
that soybean meal is relatively low in methionine and 
methionine+cysteine. However, when we look at tryptophan, threonine, 
isoleucine, and valine you'll see that the soybean protein has a greater 
concentration then what is required by the pigs. So again, soy protein 
will greatly enhance the quality of the protein that a pigs will receive 
because it has a high concentration of the indispensable amino acids.

Slide 9
However, when we formulate diets fed to pigs, we formulate diets not 
only based on the concentration of the amino acids, we also formulate 
based on the concentration of digestible amino acids. To do that, we 
need to have a digestibility value for each amino acid that is present 
in soybean meal. And the way we determine these digestibility values is 
by inserting a little cannula into the distal ileum of the pig because 
we need to collect the fluids that are coming out of the distal ileum of 
the pig and that can be done only if we have a cannula in the small 
intestine there.

So we had to do a small surgery, put in the cannula into the intestines, 
and then we can actually open that cannula and we can get fluids out and 
then we can analyze that and from there we can calculate the ileal 
digestibility of amino acids.

Slide 10
When we look at the standardized ileal digestibility of amino acids in 
soybean meal we'll see here that the digestibility of most amino acids 
in dehulled soybean meal is slightly greater than in nondehulled soybean 
meal. And the reason for that is that the digestibility of amino acids 
in the hulls is a little bit less than in the rest of the soybean 
protein. And because there are more hulls and in the nondehulled soybean 
meal than in the dehulled soybean meal, we get a little bit greater 
digestibility for most amino acids in the dehulled soybean meal.

Slide 11
If we compare the digestibility of amino acids in soybean meal to the 
digestibility of amino acids in a couple of other protein sources, we'll 
see here that the digestibility of amino acids in soybean meal which is 
shown in the red bars is greater than the digestibility of amino acids 
in canola meal which is shown in the yellow bars and quite a bit greater 
than the digestibility of amino acids in DDGS which is shown in the blue 
bars. From that we can see that not only does soybean protein have great 
quality and we have relatively high concentrations of amino acids in 
soybean protein but we also have a relatively high digestibility of 
these amino acids and in particular when we compare the digestibility of 
amino acids in soybean meal to that of other protein sources we see that 
that the digestibility is pretty impressive for soybean protein.

Slide 12
I also want to talk a little bit about the effects of soybean oil on 
amino acid digestibility.

Slide 13
And here we have some data from an experiment we conducted in our lab a 
few years ago. And we have the average digestibility of lysine, 
methionine, threonine, and tryptophan from soybean meal and soy protein 
concentrate. The yellow bars here represent these feed ingredients 
without any oil added to the diets. The red bars represent the 
digestibility of soybean meal and soy protein concentrate when we added 
7% soybean oil to the diets. And what we will note here is that for all 
four amino acids we see a significant increase in digestibility when we 
add oil to the diets. And we have actually repeated this experiment a 
couple of times and observed the same thing in other experiments so we 
are convinced that addition of soybean oil to diets increases the 
digestibility. We don't have a definitive answer on why that is but we 
believe that the reason soybean oil has this impact on amino acid 
digestibility is that by adding soybean oil to the diets we've reduced 
transit time -- that means the passage rate in the intestinal tract of 
the pigs -- and therefore the enzymes have more time to digest the 
proteins, and that's more time for the amino acids to be absorbed over 
the intestinal wall. So we believe that is a reason we see this increase 
in digestibility when we add soybean oil to the diets.

Slide 14
When soybean meal is produced, one of the steps that is required during 
that process is that the soybean meal has to be toasted, or heated. 
There is a risk this heating step can damage the protein in soybean 
meal. So let's talk a little bit about how to avoid that and how to 
check if soybean meal has been heat damaged.

Slide 15
First of all, let's briefly go through the process that can result in 
damage of protein in soybean meal and in any other feed ingredient. The 
chemical reaction that may take place after heating is called the 
Maillard reaction. And the Maillard reaction is mainly a problem for 
lysine, but it will impact all amino acids in the protein. But using 
lysine as an example here, we'll see that lysine starts out being 
converted to some Schiff bases if we apply heat to the protein. Those 
Schiff bases can be converted back to lysine, in particular if they are 
put in an acidic environment. However, if we further heat the protein 
then the Schiff bases, instead of converting back to lysine, will be 
converted to compounds that we call Amadori compounds. And from this 
point forward, there is no way back. So we cannot convert Amadori 
compounds back to lysine. However, if we continue to heat the protein, 
the Amadori compounds may be converted into premelanoidins and 
melanoidins. And melanoidins are cyclic compounds that are completely 
undigestible to pigs. What happens here during this reaction is that the 
amino group of lysine -- which is supposed to contain a nitrogen group 
and two hydrogens -- that amino group can be converted so it contains a 
nitrogen, one hydrogen, and one sugar molecule. This reaction will take 
place if the protein is heated at the same time as we have sugars 
available in the reaction. And remember, when we talked about the 
composition of soybean meal, we talked about the presence of sugars and 
sucrose in soybean meal. So every time we heat soybean meal there will 
be sugars available and those sugars can then be used in this Maillard 
reaction and turn lysine into an unreactive lysine by attaching the 
sugar molecule at the nitrogen instead of one of the hydrogens. So by 
doing that, we have converted a reactive lysine into an unreactive 
lysine and the unreactive lysine cannot be utilized by the pig for 
protein synthesis. Some of the unreactive lysine cannot be absorbed but 
some of it will be absorbed. Generation of Amadori compounds will reduce 
lysine digestibility and it will also reduce the analyzed concentration 
of lysine in the soybean meal. Generation of melanoidins will result in 
destruction of lysine so if we have converted a lot of lysine into 
melanoidins, then we would have a reduced concentration of lysine in 
that protein. So that's the general reaction that takes place when we 
overheat feed proteins including soybean meal.

Slide 16
Here are some data from an experiment we conducted in our laboratory. 
And in this case we started out with one sample of soybean meal -- we 
call that the control sample, that was just regular soybean meal. We 
then autoclaved that sample for either 15 or 30 minutes at 125 degrees 
Celsius and you can see here that the color changed, meaning it became 
more brown as we heated it therefore we assumed it was heat damaged. We 
also took one sample that we oven dried at 125 degrees Celsius for 30 
minutes and you can see here that the color did not change when we oven 
dried the soybean meal. And on the previous slide we talked about 
generation of melanoidins if lysine is heat-damaged. And melanoidins are 
brownish pigments therefore the more melanoidins we have the browner the 
feed protein would become. And in this case we can clearly see that the 
soybean meal became browner, and we also measured that by determining 
the L* value and the a* value. And L* value goes down from 76 to 52.5 
amd the a* goes up from 3.4 to 12.5 as we autoclave the samples. We can 
clearly see that the color changed when we autoclaved them. However, the 
oven dried samples did not change in color, and we can also see that 
both L* and a* values here did not change. So this means that it's not 
only the amount of heat we apply to the protein that is important; it's 
also type of heat. And autoclaving applies heat in the presence of 
water, steam, and high pressure and that's the reason we destroy the 
protein when we autoclave it, whereas oven drying here is a dry heat 
without any steam or water application and there we don't get that same 
destruction of the protein.

Slide 17
We then fed these proteins to pigs, and here are data for the control 
and also for the two autoclaved samples. And we can see here that as we 
autoclaved the samples for either 15 or 30 minutes the digestibility -- 
both the apparent ileal digestibility which is shown in the red graph 
here, and the standardized ileal digestibility which is shown in the 
blue graph -- both of these graphs go down as we heat treat the soybean 
meal. So clearly we have reduced the digestibility as we heat treated 
the soybean meal.

Slide 18
As we saw on the first slide about the Maillard reaction, heat damage 
will not only reduce the digestibility, it will also reduce the 
concentration of lysine in soybean meal. And on this slide, we can see 
that crude protein did not change among the treated soybean meal 
samples. However, the lysine was reduced from 3.05% to 2.83% in the 
sample that was autoclaved for 15 minutes, and 2.69% in the sample that 
was autoclaved for 30 minutes, and it was not changed in the oven dried 
sample. So, we saw before that lysine digestibility was reduced when we 
autoclaved the sample and here we can see that lysine concentration is 
also reduced. So again, as we saw on the first slide about the Maillard 
reaction, both lysine digestibility and lysine concentration is reduced 
when we heat damage soybean meal. Because the protein is not changed 
when we heat damage the soybean meal, we can actually estimate the 
degree of heat damage by calculating what we call the lysine:crude 
protein ratio. That means we take the lysine as a percentage of crude 
protein. And if we do that we will see that the control soybean meal 
here has a lysine:crude protein ratio of 6.29, the autoclaved sample for 
fifteen minutes has a ratio of 5.75, and the sample that was autoclaved 
for thirty minutes has a ratio of 5.57. So, the lysine:crude protein 
ratio is reduced as we heat damage the soybean meal. And you can also 
see here that the oven dried sample has the same lysine:crude protein 
ratio as the control, again indicating that the oven dried sample was 
not heat damaged.

Slide 19
What we've seen here on heat damage is that if we calculate lysine as a 
percentage of crude protein in soybean meal, then we can estimate the 
degree of heat damage in this soybean meal. And in general, if 
lysine:crude protein ratio is greater than 6% then the meal is not 
damaged, but if it's less than 6% then we probably have a heat-damaged 
soybean meal. So, we recommend that users of soybean meal calculate the 
lysine:crude protein ratio and by that, they can easily determine if the 
soybean meal is heat damaged or not. If it's above 6% it's not heat 
damaged, and if the lysine:crude protein ratio is less than 6% it is 
heat damaged.

Slide 20
Soybean meal provides amino acids to the diets and that's the main 
reason why we use soybean meal in diets for pigs. However, soybean meal 
also provides quite a bit of phosphorus so let's talk a little bit about 
the digestibility of phosphorus in soybean meal.

Slide 21
This slide shows the concentration of phosphorus in soybean meal. You 
will see in this case, we have a total of 0.66% phosphorus in dehulled 
soybean meal, which is close to the average we find in soybean meal. If 
we analyze for phytate, we'll see there's 1.51% phytate in soybean meal. 
And phytate is a small molecule that can bind six molecules of 
phosphorus. So, we can calculate how much phosphorus is bound to 
phytate, and on average that's about 28.2%. So if we take 28.2% of 1.51% 
phytate, then we can calculate that about 0.43% phosphorus in soybean 
meal is bound to phytate. And then from there, we can calculate how much 
of the phosphorus in soybean meal is not bound to phytate, and that 
value is the difference between the total phosphorus and the phytate 
bound phosphorus in soybean meal -- in this case 0.23%. Now, pigs and 
poultry, they don't digest the phytate bound phosphorus very well. So 
out of the total of 0.66% phosphorus here, it's only about one-third -- 
0.23% -- that is easily utilized by pigs. The other 0.43% are usually 
not utilized by pigs. They are excreted in the manure from the pigs and 
therefore if the manure is not spread on the fields it can contribute to 
environmental problems.

Slide 22
However, if we add the enzyme phytase to diets fed to pigs, then we can 
increase the digestibility of phosphorus because we can break that bond 
that binds the phosphorus to the phytate molecule and liberate some of 
that phosphorus. And we can see here that by adding phytase to soybean 
meal, we can pretty dramatically increase the digestibility from about 
44% up to more than 70% in soybean meal. So, by doing that, we actually 
have a pretty high digestibility of phosphorus in soybean meal. But even 
without phytase we have a relatively good digestibility of about 44% in 
soybean meal. So phosphorus is well utilized in soybean meal when we 
feed that soybean meal to pigs, and in particular when we add phytase to 
the diets.

Slide 23
When we feed soybean meal, we also get energy. And we can determine the 
digestibility of energy by subtracting the energy that is excreted in 
the feces from pigs when we feed them soybean meal. And if we also 
subtract the amount of energy that is excreted in the urine from the 
pigs, then we can calculate the metabolizable energy in soybean meal.

Slide 24
Here are data from six different experiments in which we have determined 
the metabolizable energy in dehulled soybean meal. And you'll see here 
there's a little bit of variation among these six experiments, but on 
average we have about 4000 kilocalories of energy per kilogram dry 
matter in soybean meal. This value is actually a little bit greater than 
what has been shown in previous research and it appears that over the 
last ten or fifteen or twenty years, the soybean meal varieties that we 
are growing now, they actually contain a little bit more energy than 
what we had in the past. So, it is appropriate to use a value for 
metabolizable energy in soybean meal of about 4000 kilocalories per 
kilogram dry matter.

Slide 25
If we compare that to the book values we ought to have values for 
digestible energy, the DE. You can see here that the values we have 
gotten at the University of Illinois over the last few years is about 
4292 kilocalories per kilogram dry matter for DE and about 4017 
kilocalories per kilogram dry matter for metabolizable energy. And if we 
divide the ME by the DE we see that ME is about 94% of all the DE. 
However, the book values which were published in the NRC publication in 
1998 states that there is only 4094 kilocalories per kilogram dry matter 
for DE and 3755 kilocalories per kilogram dry matter for ME. That is a 
difference of more than 200 kilocalories per kilogram dry matter for ME, 
and it appears that the newer varieties of soybeans that we are growing 
now, they result in more DE and more ME in the soybean meal than what we 
had in the past. So we probably need to update those book values. So the 
bottom line is that there is actually a little bit more energy provided 
in diets fed to pigs when we add soybean meal to the diets than what we 
had in the past.

Slide 26
So, a few conclusions from this presentation.

Slide 27
We have seen that soybean meal is an excellent source of amino acids 
that can be used in diets fed to swine. The amino acid composition is 
very favorable relative to the requirements of pigs and we also saw that 
we have a very high concentration of digestible amino acids in soybean 
meal. The digestibility of amino acids in soybean meal in general is 
greater then that of other protein sources. And soybean meal can easily 
provide all the amino acids that are needed in the diets fed to pigs 
above twenty kilograms body weight.

Slide 28
We also saw that soybean meal contains both calcium and phosphorus and 
the digestibility of phosphorus is greater than what has previously been 
determined. And in particular, if we add phytase to the diets then we 
can get digestibility of phosphorus that is about 70%, which is much 
greater than previously reported. And likewise, the concentration of 
digestible energy and metabolizable energy in soybean meal is greater 
than in corn, and the ME value for soybean meal is greater than what we 
have for the current book values. So, we actually get more energy into 
the diets when we use soybean meal than what we assumed in the past and 
that is likely because the varieties of soybeans we grow today they 
result in a greater concentration of energy in soybean meal than what we 
had in the past.

Slide 29
So that concludes our presentation here, so I want to thank you for your 
attention. For more information about soybean meal and other feed 
ingredients fed to pigs, please visit our website at 
nutrition.ansci.illinois.edu. And on the website, we have lots of 
information about many different feed ingredients. There's also a 
newsletter that is free -- all you have to do to subscribe is to provide 
your email address and once a month you'll then get our newsletter. 
There are also many previous podcasts on the website that you can listen 
to if if you want to. Thank you again for your attention.