Slide 1
Hello. I am Hans Stein from the University of Illinois, and I will talk 
to you today about methodologies for evaluating quality of feed 
ingredients. This is part of a presentation that I gave at the Midwest 
Animal Science Meeting in Des Moines in March 2011. And today, I will 
present the first part of this presentation, and talk about feed 
ingredient composition. The remainder of the presentation will be 
recorded at a later time.

Slide 2
So when we talk about nutrition in general, we talk about three main 
areas. The first area we talk about is what we feed to the animals. That 
means the composition of the feed ingredients that go into our diets -- 
the nutrients, the energies and so forth -- and also the antinutritional 
factors and maybe toxins if they are present. Those are all related to 
the feed ingredients that we use. The second area of nutrition is what 
happens to these feed ingredients when they are ingested by the animal 
and get into the GI tract. And here we talk about digestion, absorption, 
and excretion of nutrients. And the third part of nutrition is what 
happens in the rest of the body after the nutrients have been absorbed 
from the GI tract. They are metabolized, new compounds are synthesized, 
compounds are deposited, and if there are any excesses, they will be 
excreted. So, these are the three main areas of nutrition, and today I 
will talk only about the first area.

Slide 3
So when we look at the nutrient composition of feed ingredients, we can 
actually learn a lot just from analyzing the concentrations of nutrients 
in these feed ingredients. The first thing we usually look at is the 
moisture level, or the dry matter concentration. And, obviously we want 
the dry matter to be as high as possible because animals get nutrients 
and energy from the dry matter part, not from the moisture part. And 
usually, most of our feed ingredients have a dry matter concentration of 
86-90% because at that dry matter level, they can be stored for longer 
periods of time. If the moisture is greater than 10-14%, we usually have 
trouble storing our ingredients, so we try to dry them down to 86-90% 
dry matter.

The second thing we might want to look at is the concentration of ash in 
our ingredients. The ash analysis is easy, and it's inexpensive, and it 
tells us a lot about the ingredient we have. And I'll give an example of 
that later. But, we have to remember that it's in the minerals part that 
the calcium and the phosphorus and other minerals are present. And we 
know that these minerals are needed by the animal, so we do need to have 
an estimate of the concentration of calcium and phosphorus and other 
minerals in the ingredients. However, we do not want high ash 
concentrations because that will reduce the concentration of other 
nutrients, and also reduce the concentration of energy in the 
ingredients.

We talk about protein, we talk about amino acids, and in particular the 
indispensable amino acids that are needed by the animals, and we 
therefore have to analyze our ingredients for amino acid composition. 
Pigs don't need protein, they only need the amino acids. And we can have 
relatively high protein concentrations without having high amino acid 
concentration, and we'll talk a little bit about that in a few minutes 
also.

Carbohydrates is not something that we always analyze ingredients for. 
However, depending on the ingredient we are looking at, it may be 
important to analyze for starch, and if we do that, we should use an 
enzymatic procedure to analyze starch because that procedure is the most 
accurate one. We may also want to analyze for fiber, and here we can use 
ADF procedures, NDF procedures, or TDF procedures, and all of these 
procedures will tell us something about the concentration of fiber in 
the ingredient, and to some degree also about the nature of the fiber 
that we have in the ingredient. In the old days, we used an analysis for 
crude fiber; however, that analysis is now recognized as not being very 
accurate, so we usually don't use that anymore.

The last thing we analyze for is fat, and when we do that, we prefer to 
use a procedure called acid hydrolyzed ether extract, and that means 
that we acid hydrolyze our ingredients prior to extracting the fat with 
ether. And this procedure will tell us the total concentration of fat in 
the ingredient. Sometimes, we may also want to know the composition of 
that fat, and if that's the case, then we need to analyze for individual 
fatty acids in the fat. And this is important if we have vegetable feed 
ingredients with relatively high concentration of fat, because some of 
these fatty acids may have negative impacts on the product quality of 
pigs and can result in soft bellies and soft backfat in pigs if they are 
fed these ingredients.

Slide 4
This is an example of why it's important to analyze for ash in feed 
ingredients. In this case, we have two different products. Both are 
called whey permeate. You will see what we call Whey-Permeate 1 contains 
8.96% ash, but what we call Whey Permeate-2 contains only 1.72% ash. And 
we can see how that influences the concentration of metabolizable 
energy. We have that measured here in ME in kcal/kg dry matter, and we 
can see that Permeate-1 contains 3081 kcal/kg dry matter, whereas 
Permeate-2, with the low ash concentration, contains 3593 kcal/kg dry 
matter. So, this illustrates why is it important to determine the ash 
concentration in these ingredients, because they directly influence the 
amount of energy that the animal can get out of the ingredients.

Slide 5
Here's an example of four different ingredients. They are all 
co-products from the corn industry. And we have corn gluten meal, corn 
germ meal, DDGS, and hominy feed. And listed here are concentrations of 
crude protein in the blue bars, acid hydrolyzed ether extract (or fat) 
in the red bars, NDF, which is the fiber, in the orange bars, and starch 
in the green bars. And we will see that corn gluten meal is a high 
protein ingredient containing more than 60% crude protein. There is, 
however, very little fat in corn gluten meal, there's a little bit less 
than 30% fiber so it's a medium high fiber concentration, and there's a 
low concentration of starch in this ingredient. Corn germ meal contains 
much less protein, contains very little fat, but contains almost 50% 
NDF, which means the fiber concentration in this ingredient is very 
high. Starch is relatively low as well. DDGS has a medium concentration 
of protein and relatively high concentration of fat -- about 10% -- and 
a medium concentration of NDF or fiber also -- about 32%. Starch is 
relatively low in DDGS. However, when we look at hominy feed, we have 
low concentration of protein, low concentration of fat, low 
concentration of fiber, and high concentration of starch. So, we can see 
from this that although all four ingredients here are co-products from 
the corn industry, they are very different in terms of their nutritional 
concentrations. And therefore it is important to analyze the ingredients 
to correctly characterize and estimate the nutritional value of these 
ingredients.

Slide 6
Here's another example of feed ingredient evaluation. We have sunflower 
seeds and sunflower meal. And sunflower seeds in the blue bar contains 
54% crude fat, or ether extract, whereas sunflower meal contains only 
1.6%. And this is no surprise because sunflower meal is simply the meal 
that is left over from sunflower seeds that have been defatted. So it's 
produced by taking the fat out of these sunflower seeds.

Slide 7
However, things aren't always as we expect them to be. And we listed 
here on the left the concentrations of nutrients in sunflower seeds: 
54.5% acid hydrolyzed ether extract, or fat, as we saw before, 22.1% 
crude protein, lysine is 0.79%, NDF is 8.1%, and moisture is 10%. If we 
take these values and we have measured 1.6% fat in the sunflower meal, 
then we should be able to calculate how much crude protein, how much 
lysine, how much NDF, and how much moisture is left in the sunflower 
meal because the sunflower meal is simply the defatted sunflower seeds. 
And if we do this calculation, we'll see that we expect sunflower meal 
to contain 47.1% crude protein, 1.67% lysine, 17.3% NDF, and 10% 
moisture. However, we recently conducted experiments with sunflower 
meal, and we got sunflower meal and sunflower seeds delivered to the 
University of Illinois, and we can see the product we got delivered is 
listed here on the right. And the acid hydrolyzed ether extract was 
1.6%, as we had expected. However, crude protein and lysine was only 
29.4 and 1.01% respectively, and not 47.1 and 1.67% as we had expected 
by calculating simply from the sunflower seeds. So, the delivered 
sunflower meal was different from what we expected, and the reason we 
had this relatively low concentration of crude protein and lysine in the 
delivered sunflower meal was that the NDF was much greater than we had 
expected. You can see here we have expected NDF concentration to be 
17.3%; however, when we analyzed the sunflower meal, we had 39.3%. So we 
conclude from this that it is important to analyze ingredients to know 
exactly what we have in there, and sometimes things are not exactly what 
we expect.

Slide 8
Here's another example of why things need to be analyzed. And I said 
before we need to analyze for amino acids, not only crude protein, to 
evaluate the crude protein portion of the feed ingredient. We have here 
three feed ingredients: soybean meal, corn gluten meal, and DDGS. The 
crude protein concentration in these three ingredients are 47.5% in 
soybean meal, 62.9% in corn gluten meal, and 27.5% in DDGS. Lysine and 
tryptophan in soybean meal are 3.02 and 0.65% respectively. However, 
corn gluten meal, which contained more crude protein than soybean meal, 
contains much less lysine: only 1.18% versus 3.02% in soybean meal. And 
also much less tryptophan: 0.44% versus 0.65%. So we can see here that 
although the crude protein concentration in corn gluten meal is greater 
than in soybean meal, the concentration of amino acids is actually much 
lower. And the same is true for DDGS. We have a lower crude protein 
concentration in DDGS compared with soybean meal, but also a much lower 
concentration of both lysine and tryptophan. And to try to evaluate 
different feed ingredients, we can actually calculate each amino acid as 
a percentage of the total crude protein concentration in that 
ingredient. If we do that, we will get an understanding of the quality 
of the protein that we have in the ingredient. And we can see here for 
soybean meal, lysine is 6.35% of the total crude protein, whereas in 
corn gluten meal, it's only 1.88%, and in DDGS it's 2.84%. So, much 
lower concentration of lysine as a percentage of crude protein in corn 
gluten meal and DDGS compared with soybean meal. And we can see the 
exact same thing is true for tryptophan; we have a greater concentration 
of tryptophan as percentage of crude protein in soybean meal compared 
with corn gluten meal and DDGS. So the bottom line here is that it's not 
enough to only analyze for crude protein when we evaluate feed 
ingredients. We need to evaluate for amino acids, and if we want to 
estimate the quality of the protein in our feed ingredients, then it is 
a good idea to express the amino acids as a percentage of crude protein 
in the ingredient, and compare ingredients that way. That will give us 
an estimate of the protein quality in the ingredient.

Slide 9
Another thing that may happen in feed ingredients is that if they are 
heated or dried, they could be damaged, and that will result in 
particular in problems for lysine and lysine digestibility; and this is 
something that happens if sugars and proteins are heated together. And 
we get something that's called a Maillard reaction, and during this 
Maillard reaction, lysine will go through a series of chemical 
reactions, and eventually give rise to products we call Amadori products 
and melanoidins. Melanoidins are cyclic compounds that are completely 
indigestible, and give no protein value to the animal. So the more 
lysine that has been turned into melanoidines, the less is the 
concentration of lysine in that ingredient. Amadori compounds, however, 
will to some degree reduce the lysine concentration, but may also reduce 
lysine digestibility. So it follows from this that if we have 
heat-damaged feed ingredient, we have a lower digestibility of lysine 
and a lower concentration of lysine in this ingredient. And this is 
because we have part of the lysine that has been made unreactive or 
undigestible because of the heat damage. We called that unreactive 
lysine, whereas part of the lysine is still reactive because it was not 
heat damaged.

Slide 10
And here's an example of soybean meal that was heat treated. You can see 
on the left we have a control soybean meal; we did not heat treat that. 
The second sample of soybean meal had been autoclaved for 15 minutes at 
125 degrees Celsius. The third sample had been autoclaved for 30 minutes 
at 125 degrees Celsius. And the fourth sample was oven dried for 30 
minutes at 125 degrees Celsius as well. And you can clearly tell here 
that the color of the two autoclaved samples changed as we autoclaved 
them, whereas the oven dried soybean meal did not change in color. And 
this is illustrated also in the numbers that are shown here for the L* 
value, which gives an indication of the lightness of the product. And as 
you would expect, the more we heat these samples, the lower is the L* 
value for the products going down from 76.7 to 61.7 and 52.5 for the 
soybean meal that was autoclaved for 30 minutes at 125 degrees Celsius. 
However, the oven dried soybean meal did not change in L* value, and 
that indicates that this sample was not heat damaged. When we look at 
a*, which is the measure of the redness of the colors, we can see the a* 
went up from 3.4 to 10.0 and 12.5% in the two autoclaved samples as they 
got heat damage, whereas the oven dried sample did not change in a* 
value. So again, we clearly see here that two of the samples that were 
autoclaved, they changed in color as they were heat damaged. We fed all 
four of these soybean meals to growing pigs, and we determined the 
digestibility of amino acids in these samples.

Slide 11
And this shows the effect of autoclaving time on the apparent ileal 
digestibility and the standardized ileal digestibility of lysine. And we 
can clearly see here that when we autoclaved the samples for 15 minutes 
or for 30 minutes, we reduced both the apparent ileal digestibility and 
the standardized ileal digestibility of lysine. And the standardized 
ileal digestibility went down from 93% to 84.2%.

Slide 12
When we take a look at the concentration of lysine and crude protein in 
these four samples of soybean meal, we see that the concentration of 
crude protein did not change as we heat treated these soybean meals. So 
crude protein stays constant. However, the concentration of lysine was 
reduced from 3.05 to 2.83 and 2.69% as we autoclaved the samples. 
Whereas the oven dried soybean meal had the same concentration of lysine 
as the control sample, indicating that the oven dried sample was not 
heat damaged. And we saw before that as we autoclaved the soybean meal 
samples, we reduced the digestibility of lysine in these samples. And 
now we see here that we also reduced the total concentration of lysine 
in the samples. And that fits with our hypothesis that heat treatment 
and heat damage will reduce the digestibility of lysine and the total 
concentration of lysine at the same time. We can get an estimate of this 
heat damage by calculating the lysine:crude protein ratio. And then 
express lysine as a percentage of crude protein. And we can see here 
that in the control soybean meal, the lysine:crude protein ratio is 
6.29%, whereas in the two autoclaved samples, it's only 5.75 and 5.57%. 
So, this shows also that the two autoclaved samples were heat damaged 
because the lysine:crude protein ratio goes down. In contrast, the oven 
dried sample had a lysine:crude protein ratio that was not different 
from the control. So what this indicates is that if we analyze our feed 
ingredients for both crude protein and lysine, then we can calculate the 
lysine:crude protein ratio. And if we know what that ratio is for the 
undamaged or the control ingredient, we know what it should be, then we 
can look at each delivered ingredient and determine if that ingredient 
was heat damaged. The control, or the undamaged, ingredient will have a 
different lysine:crude protein ratio for each ingredient. So that is 
something that is unique for each ingredient. But once we have 
established that, we can actually look at each delivered ingredient and 
determine what the degree of heat damage in this ingredient is. So 
again, calculaitng lysine:crude protein ratio helps us estimate the 
quality of the protein in the ingredients.

Slide 13
So this concludes the first part of our presentation on methodologies to 
evaluate feed ingredients. And the second part will be available 
shortly, and in the second part, we will discuss what happens to the 
nutrients that are present in the feed ingredients after the pig has 
ingested the feed. So with that, I would like to thank you for your 
attention, and if you are interested in more information, please visit 
our website at nutrition.ansci.illinois.edu. Thank you very much.