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Hi. My name is Dr. Sarah Cervantes-Pahm, and I am here to present to you one of our studies
entitled, "The effect of novel carbohydrates on apparent ileal disappearance and apparent
total tract disappearance of gross energy and nutrients in semi-purified diets fed to
pigs." This experiment was presented at the American Society of Animal Science Midwest
Conference in 2011 under Abstract #232.
So, for our introduction: Novel carbohydrates are indigestible in the small intestines.
And for that reason, they are considered dietary fibers. And they are intended to be added
to food and beverages to increase the dietary fiber intake in humans. In a previous experiment,
we have measured the caloric value of four novel carbohydrates. So in this experiment,
we want to determine the effect of adding novel carbohydrates to the diets in pigs.
Therefore, the objective of this experiment was to determine the effect of novel carbohydrates
on the apparent ileal disappearance and apparent total tract disappearance of gross energy
and nutrients in semi-purified diets containing cellulose and four novel carbohydrates fed
to growing pigs.
We used six carbohydrates in this experiment. We used maltodextrin as a positive control,
and we used maltodextrin because it's a very digestible form of carbohydrate. We also used
cellulose as a negative control. We chose cellulose because it is a carbohydrate that
is well-characterized as an insoluble and poorly-fermentable fiber. The novel carbohydrates
that we used for this experiment were also the novel carbohydrates that we used for our
previous experiment. And these novel carbohydrates were the two types of insoluble fiber, resistant
starch 60 and resistant starch 75 (the 60 and the 75 denoting the concentration of TDF
in these fiber ingredients). And two types of soluble fibers: soluble corn fiber 70 and
pullulan.
Our hypothesis for this experiment is that the apparent ileal disappearance of gross
energy and crude protein will be lower in the diets containing cellulose and novel carbohydrates
compared with the maltodextrin-casein control diet.
Our second hypothesis is that, although dietary fibers are not digestible in the small intestines,
we believe that a fraction of the TDF in the diet disappears in the small intestines.
So for our materials and methods, we used a total of 24 pigs that were fitted with ileal
cannulas. We prepared six diets. Diet 1 was our control diet, and it was basically a maltodextrin-casein
based diet. For diets 2-6, we replaced 10% maltodextrin with 10% of cellulose or each
of the novel carbohydrates. The novel carbohydrates were therefore the only source of TDF in the
diet.
For our results...
This graph presents the concentration of TDF in the ingredients. I would like to point
out that the analytical procedure that was used to measure TDF in this experiment is
AOAC method 991.43, which you could see in the lower right-hand corner of your slide.
And you would see later on that this method has some limitations.
Based on this method, maltodextrin -- in the red bar -- contained 1.2% TDF. The occurrence
of a small amount of TDF is unexpected because maltodextrin is a very digestible carbohydrate.
The presence of a small amount of TDF in maltodextrin may indicate that maltodextrin may only be
99% digestible or that this value reflects a limitation of the AOAC method 991.43 for
TDF analysis.
Cellulose -- in the blue bar -- contained 100% TDF, RS 60 -- in the green bar -- contained
62.9% TDF, and RS 75 -- in the yellow bar -- contained 75.6% TDF.
Soluble corn fiber 70 -- in the [light] blue bar -- only contained 10% TDF using this method.
This is one of the limitations of AOAC 991.43. Because soluble corn fiber is composed of
low molecular weight carbohydrates that are soluble in ethanol, this method poorly recovers
the dietary fiber fractions in soluble corn fiber resulting to low TDF values. However,
when AOAC method 2001.3 is used, soluble corn fiber 70 has at least 70% TDF. This indicates
that AOAC method 991.43 is not the suitable TDF method to measure the concentration of
TDF in soluble corn fibers.
This graph shows the effect of the addition of cellulose or the novel carbohydrates in
the diets on the AID of gross energy.
The AID of gross energy in the maltodextrin control diet is 96.8% and we could see that
the addition of cellulose and the novel carbohydrates in the diet reduced the AID of gross energy
to varying degrees.
Among the insoluble fibers, the addition of cellulose reduced the AID of gross energy
to a greater extent (at 11 percentage units) than the addition of either RS 60 or RS 75
(which reduced the AID of gross energy by 6.3 to 8.2%). However, between the resistant
starches, RS 75 reduced the AID of gross energy more than RS 60.
The addition of soluble corn fiber 70 and pullulan to the diet reduced the AID of gross
energy to a similar extent. There was no difference in the AID of gross energy among RS 60, soluble
corn fiber, and Pullulan.
Looking at the effect of adding cellulose or novel carbohydrates on the digestibility
or disappearance of carbohydrates, we could see from this graph that the addition of cellulose
and the novel carbohydrates reduced the AID of carbohydrates in the diets.
This indicates that the reduction in the ileal digestibility of gross energy in diets added
with cellulose or the novel carbohydrates is because of the reduction in the ileal digestibility
of carbohydrates in the diets.
And this is important because a reduced ileal digestibility of carbohydrates implies that
less energy is absorbed as glucose and this physiological effect is specially important
to manage blood sugar concentrations, especially in diabetic patients.
We also look at the effect of adding cellulose or novel carbohydrates in the ileal digestibility
of crude protein in the diets. As we can see from this graph, the addition of cellulose
and pullulan, but not RS 60, RS 75, and soluble corn fiber 70, reduced the protein digestibility
in the diet. A reduction in the digestibility of protein is an undesirable characteristic
in a fiber ingredient. Therefore it is important to choose a fiber ingredient that can reduce
carbohydrate digestibility, but not protein digestibility.
We tried to explain the reduction in the AID of CP in the diets added with cellulose and
pullulan. If you look at the values at the bottom, these values are the water binding
capacity of the diets. And what we noticed is that diets containing cellulose and pullulan
had a greater water binding capacity than diets containing RS 60, RS 75, soluble corn
fiber, or maltodextrin. Therefore, we believe that the reduction in the crude protein digestibility
in diets containing cellulose and pullulan is because of its greater capacity to bind
water.
So for our second hypothesis, and that is that a fraction of the TDF in the diet will
disappear in the small intestines, we determined the fraction of TDF that disappears in the
different segments of the digestive tract.
In this experiment, we observed a high SEM which makes the data less sensitive to pick
up differences among treatment means.
However, from this graph, we could see that the AID of TDF in the maltodextrin diet was
negative. This indicates that some endogenous compounds were analyzed as TDF, because the
concentration of TDF in the ileal digesta was more than what was consumed from the maltodextrin
diet.
The AID of TDF in cellulose is only 15.7%. The disappearance of TDF in RS 60 and pullulan
diet was greater than in the cellulose diet at 44 and 49%, respectively.
We also observed a negative value for the disappearance of TDF in the soluble corn fiber
diet. Considering that the method 991.43 is not suitable to measure TDF in soluble corn
fiber it is difficult to draw conclusions on the ileal disappearance of TDF from the
soluble corn fiber diet.
Looking at the apparent total tract disappearance of TDF, the apparent total tract disappearance
of TDF in the maltodextrin diet is again negative, strongly suggesting that some endogenous compounds
were analyzed as TDF.
35% of the TDF in cellulose disappeared over the total tract indicating that cellulose
is a poorly fermentable fiber, whereas the TDF in RS 60 and pullulan disappeared at about
56 and 49% respectively.
The negative disappearance of TDF in the soluble corn fiber diet is difficult to interpret.
Not only because of the analytical issue involved with soluble corn fiber, but because of the
endogenous losses that possibly could be analyzed as TDF. But relative to the disappearance
of TDF in the maltodextrin diet, the lesser negative value of disappearance of TDF in
the soluble corn fiber diet suggest that the fiber in soluble corn fiber is not fermentable.
However, this conclusion is not consistent with reports from literature indicating the
the fiber in soluble corn fiber is fermentable.
Therefore, we decided to calculate the amount of endogenous compounds that was analyzed
as TDF.
The endogenous loss of TDF at the ileum was 25.25 g/kg dry matter intake, and over the
total tract, the endogenous loss of TDF was calculated at 42.87 g/kg dry matter intake.
We believe this is the first reported value of endogenous loss of TDF.
Using this values, we removed the influuence of endogenous compounds that were analyzed
as TDF, and we calculated for the standardized ileal disappearance of TDF and the standardized
total tract disappearance of TDF.
We could see from this slide that the SID of TDF in the soluble corn fiber diet is not
anymore negative. And we could also see that the SID of TDF in the cellulose diet is at
35.8% and was less than the SID of TDF in RS 60, soluble corn fiber, and pullulan. The
SID of RS 75 was not different from that of cellulose.
This graph also indicates that a substantial amount of TDF -- approximately 55% if we do
not include the value for soluble corn fiber -- disappears in the small intestines. Whether
this disappearance is attributed or can be attributed to the fermentation in the small
intestines or to the solubility of the fiber in the novel carbohydrates cannot be determined,
and that is something that needs to be explored and studied further.
This graph presents the standardized total tract disappearance of TDF in the diets. And
we could see that the STTD of TDF in cellulose is 68.8%, and the STTD of TDF in RS 60, RS
75, and pullulan was not different from cellulose. The STTD of RS 60, RS 75, and pullulan was
also not different from each other. So we could see from this slide that the disappearance
of TDF in the novel carbohydrates is quite substantial at 85% if we exclude the value
for soluble corn fiber 70.
So in conclusion, this experiment has shown that novel carbohydrates included at 10% in
the diet reduced the AID of gross energy by the reduction in the AID of total carbohydrates.
This experiment has also shown that the addition of cellulose and pullulan -- but not RS 60,
RS 75, and soluble corn fiber 70 -- reduced the AID of crude protein. We have also observed
that some TDF disappeared in the small intestines, and we believe that some endogenous compounds
were analyzed as TDF.
Thank you for your attention. And if you want more information on swine nutrition and feeds
and feeding, we would welcome you to our website at http://nutrition.ansci.illinois.edu. Thank
you, and have a great day.