Hi.
My name is Oscar Rojas, and I'm a master's
student in Dr. Stein's Monogastric Nutrition
Laboratory.
And today, I will have the pleasure to talk
about phosphorus and amino acid digestibility
in fermented and conventional soybean meal
fed to weanling pigs.
For the outline of my presentation, I will
start with an introduction, and then I will
move on to the first and the second experiments,
which are phosphorus digestibility and amino
acid digestibility, and finally some conclusions,
and the implications of this research.
As part of my introduction, later on I will
explain how phosphorus is present in conventional
soybean meal, and how phytate concentration
and microbial phytase have an effect on the
digestibility of phosphorus.
Fermentation of conventional soybean meal
is an important process, and the main reason
of this is because young pigs cannot tolerate
conventional soybean meal due to the presence
of anti-nutritional factors in conventional
soybean meal, which have a negative effect
in the digestion and absorption of nutrients.
And that's why we use fish meal in weanling
pig diets.
However, fermentation of conventional soybean
meal may remove these anti-nutritional factors.
At this point, I would like to mention that
fermented soybean meal is produced now in
the U.S. and is also available in the market
right now.
Most of the phosphorus in conventional soybean
meal is bound in the phytate molecule.
The phytate-bound phosphorus is not available
to the pigs because the pigs have limited
endogenous phytase activity.
And therefore phytate-bound phosphorus is
excreted in the feces, which may contribute
to environmental problems.
However, when we add phytase enzyme, which
is the one that hydrolyzes the phytate-bound
phosphorus, digesting the phytate molecule,
and the result of the addition of this phytase
is going to be an increase in the digestibilty
of phosphorus.
So however, we don't know exactly what happens
when conventional soybean meal is fermented.
Perhaps we can say that fermentation of conventional
soybean meal may result in hydrolysis of phytate
and release the phosphorus.
So our hypothesis here is that fermentation
can break these phytate bonds and therefore
increase the digestibility of phosphorus.
In this slide, I am going to explain briefly
how is the fermentation of conventional soybean
meal.
We start again with the conventional soybean
meal that is the byproduct of the production
of soybean oil.
This conventional soybean meal is going to
be soaked and then cooked and then inoculated
with Aspergillus oryzae and Bacillus subtilis
to produce fermented soybean meal.
In this slide, I am going to show you what
is the composition of fermented and conventional
soybean meal.
For crude protein, it's slightly higher in
fermented soybean meal, which is 55.5%, than
in conventional soybean meal, which is 47.2%.
When we look at dry matter, it's slightly
higher, too, in fermented soybean meal, 90.8%
and in conventional soybean meal just 88%.
When we look at ether extract, it's around
the same value -- 1.4% in both sources.
And ash and lysine is slightly higher in fermented
soybean meal than in conventional soybean
meal.
So what is the distribution of phosphorus
in fermented and conventional soybean meal?
The total phosphorus in fermented soybean
meal is 0.78 versus 0.66 in conventional soybean
meal.
Remember that I mentioned before that the
two forms of phosphorus are phytate-bound
phosphorus and non-phytate phosphorus.
The phytate-bound phosphorus in fermented
soybean meal is 0.39 and in conventional soybean
meal is 0.43.
When we look at non-phytate phosphorus, it's
0.39 in fermented soybean meal and 0.23 in
conventional soybean meal.
This means that 50% of the total phosphorus
is phytate-bound phosphorus in fermented soybean
meal, and the other 50% is non-phytate phosphorus
in fermented soybean meal.
In the case of conventional soybean meal,
64.5 is phytate-bound phosphorus, and 35.5%
is non-phytate phosphorus.
So maybe at this point, we can start thinking
that fermentation can have an effect in the
concentration of phytate-bound phosphorus
in conventional soybean meal.
So let's move on to the first experiment.
The objective of this experiment was to test
the hypothesis that the STTD of phosphorus
in fermented soybean meal is greater than
in conventional soybean meal.
In this experiment, we used 30 barrows with
initial body weight around 14 kg.
They were put in metabolism cages, and they
were allotted in a randomized complete block
design with five diets.
We used six pigs per treatment, and feces
samples were collected after five days adaptation
period.
So how did we calculate the ATTD and STTD?
ATTD is calculated by simply subtracting the
output phosphorus from the intake phosphorus.
And then divide it for the phosphorus intake.
When we calculate STTD, it is basically just:
correct ATTD values by the basal endogenous
phosphorus losses.
This means that we subtract the basal endogenous
losses from the phosphorus output and then
we subtract the phosphorus intake, and then
divide it by the phosphorus intake.
So what are the composition of the experimental
diets?
We formulated two fermented soybean meal diets
-- one without phytase and the other one with
phytase -- and we included fermented soybean
meal at 47% in the first and the second diets.
We also formulated two conventional soybean
meal diets -- one without phytase and the
other one with phytase -- and we included
conventional soybean meal at 50% in the third
and the fourth diets.
In addition to these four diets, we formulated
a phosphorus-free to measure the basal endogenous
phosphorus loss.
These data were analyzed as a 2x2 factorial,
and we used the Proc Mixed procedure.
The fixed effects were the sources of soybean
meal, phytase, and the interaction between
soybean meal and phytase, and the random effect
was the replicate.
So let's move on into the results.
So just take a minute to set up this slide.
In the Y-axis, we have the digestibility in
percent, and in the X-axis, we have on the
left the fermented soybean meal, and on the
right the conventional soybean meal.
The red bar represents without phytase, and
the blue bar represents with phytase.
The STTD of phosphorus was greater when phytase
was used than if no phytase was included in
the diets, regardless of the source of soybean
meal.
The increase in STTD when phytase was used
was, however, greater for conventional soybean
meal than for fermented soybean meal.
The reason of this observation may be that
the amount of phytate-bound phosphorus is
greater in conventional soybean meal than
in fermented soybean meal.
And therefore, phytase hydrolyzed more phytate
in conventional soybean meal than in fermented
soybean meal, and increased the digestibility
of phosphorus.
The digestibility of phosphorus was greater
in fermented soybean meal than in conventional
soybean meal.
And this observation is the result of the
reduced concentration of phytate-bound phosphorus
in fermented soybean meal compared with conventional
soybean meal.
So at this point, I would like to emphasize
that fermenttaion did indeed reduce the amount
of phytate-bound phosphorus, and indeed increase
the digestibility of phosphorus.
However, you could get the same increase in
conventional soybean meal by adding phytase
to the diet.
The conclusions for this experiment are the
STTD of phosphorus is greater in fermented
soybean meal than in conventional soybean
meal if microbial phytase is not added to
the diet, and if phytase is used, there is
no difference in STTD of phosphorus between
fermented soybean meal and conventional soybean
meal.
Let's move on to the second experiment.
The objective of this experiment was to determine
the standardized ileal digestibility of amino
acids in fermented soybean meal and to compare
these values to the values obtained for conventional
soybean meal and fish meal.
In this experiment, we used eight barrows
with initial body weight around 10.4 kg.
We formulated four diets, and ileal digesta
were collected for eight hours on days 6 and
7 of each period.
The experimental design was a repeated 4x4
Latin square with four periods and four diets.
What are the composition of the experimental
diets?
We formulated three cornstarch-based diets,
and we included at the first diet fermented
soybean meal at 30%.
We included also conventional soybean meal
in the second diet at 33%, and fish meal in
the third diet at 25%.
In addition of these three diets, we formulated
a nitrogen-free diet to calculate the basal
amino acid endogenous losses.
These data were analyzed by Anova using the
Proc Mixed proceudre.
The fixed effect was the diet, and the random
effects were the pigs and the replicate.
So let's move on into the results.
When we look at SID of lysine, we didn't observe
any significant difference among treatments.
However, when we look at SID of methionine,
we observe that in fermented soybean meal,
was greater than in conventional soybean meal
and that in fish meal.
When look at the SID of threonine, we didn't
observe any significant difference among treatments.
And when we look at the SID of tryptophan,
we have the same pattern of lysine and threonine:
no significant difference among treaments.
In this slide, we are looking at digestible
amino acids g/kg.
You can obtain these values when you multiply
the amino acid concentration in the ingredient
by the SID coefficient.
We observe here that fish meal has greater
digestible lysine, methionine, and threonine
than fermented soybean meal and conventional
soybean meal.
And the reason of this observation is that
fish meal has more lysine, methionine, and
threonine concentration than in fermented
soybean meal and conventional soybean meal.
However, when we look at digestible tryptophan,
it's greater in fermented soybean meal and
in conventional soybean meal than in fish
meal.
And once again, it's because fermented soybean
meal and conventional soybean meal have greater
tryptophan concentration than fish meal.
So the conclusion for these experiments are:
the fermentation of conventional soybean meal
does not reduce the amino acid digestibility;
and the SID of most amino acids is not different
between fermented soybean meal and conventional
soybean meal, but these values are greater
than in fish meal.
The implications of this reasearch are that
fermented soybean meal contains more digestible
phosphorus than conventional soybean meal,
which reduces the need for inclusion of inorganic
phosphorus in diets containing fermented soybean
meal.
And fermentation of conventional soybean meal
does not affect the amino acid digestibility
and therefore fermented soybean meal can be
used for diets fed to weanling pigs.
So I would like to thank you for your attention,
and I hope this information was useful.
And if you want to know more about phosphorus
and amino acid digestibility, you are more
than welcome to watch the other presentations
in our web site.
