Hello. My name is Neil Jaworski, and I am a Ph. D. student in the Stein
Monogastric Nutrition Laboratory. In this podcast, I will present an experiment
conducted to test the effects of fiber, a direct fed microbial, and feeding
duration on ileal and total tract digestibility of energy and nutrients by pigs.
This abstract was presented at the ASAS Midwest Section meeting in March in Des
Moines, Iowa, and it was abstract #161.

We will begin this podcast with the take home message. And my hope is that it
will spark your curiosity to continue listening to find out how we come to these
conclusions. The first take home message is that a five day adaptation period to
high fiber diets is sufficient when determining concentrations of DE and ME in
diets fed to pigs. And this is very important, because most of the time when we
submit publications that determine the DE and ME in high fiber diets, reviewers
always questions whether or not a five day adaptation period is sufficient.

A second take home message is that high fiber diets reduce ileal and total tract
digestibility of nutrients and energy, whereas DFM, or direct fed microbial,
addition did not ameliorate this negative effect. But DFM addition to a
corn-soybean meal low fiber diet increased the apparent ileal digestibility of
ADF, NDF, and lysine.

Finally, we determined that concentrations of digestible and metabolizable
energy in diets increased 0.8 and 2.1% respectively over a six-week feeding
period, because the apparent ileal digestibility of starch increased over that
time.

So now that you know the take home messages, we'll go into the introduction and
why we conducted this experiment. So direct fed microbials, which I'll
abbreviate as DFM for the remainder of this presentation, have been indicated
that they may increase nutrient digestibility. We wanted to answer the question,
"How long do we need to feed the DFM to observe the increase in nutrient
digestibility?" as well as, "Does the DFM have the potential to colonize the
gastrointestinal tract of the pig, and therefore we can remove the DFM from the
feed and still maintain increased nutrient digestibility benefits without
feeding the DFM?".

Dietary fiber, on the other hand, has been indicated to decrease nutrient and
energy digestibility. And this is an acute effect, it happens in a relatively
short time of feeding the dietary fiber, whereas when we feed dietary fiber for
a prolonged period of time, we observed increased gastrointestinal tract size
and increased microbial population in the gastrointestinal tract. And this is a
chronic effect of dietary fiber—it happens over a long period of time. And we
hypothesized that as we feed dietary fiber over this long period of time, the
increased GI tract size and microbial population would increase the pig's
ability to digest ADF and NDF, or fiber, from its diet.

Therefore, objective #1 of this experiment was to determine the effects of a
3-strain Bacillus-based direct fed microbial added to corn-soybean meal or
corn-soybean meal-DDGS-wheat middlings diets on apparent ileal digestibility and
apparent total tract digestibility of energy and nutrients.

And objective #2 was to determine the AID and ATTD of nutrients and energy in
corn-soybean meal and high-fiber diets with or without the addition of the DFM
over a period of 12 weeks.

We utilized 24 ileal cannulated barrows with an initial body weight of 31.5 ± 1
kg, randomly allotted to 24 different metabolism crates like the one shown in
the picture, that allowed for the total but separate collection of feces and
urine. And these pigs were allotted to four different treatments in a randomized
complete block design. Within the four treatments, we had two different diet
types—the low fiber diet, or our standard corn-soybean meal diet, or our high
fiber diet, which contained corn, soybean meal, DDGS, and wheat middlings—and
then two levels of DFM: 0 or 60 grams DFM per ton of feed. And the DFM contained
1.5 *10^5 colony forming units per kg.

The corn-soybean meal experimental diets, or the low fiber diets, were
formulated to contain corn and soybean meal, and then we replaced 0.06% corn
with DFM for the diet containing the direct fed microbial.

Two additional diets were formulated as the high fiber diets, where we replaced
some corn and soybean meal with 30% DDGS and 10% wheat middlings. Again, we
replaced 0.06% corn in the diet without DFM with the DFM in the diet containing
the direct fed microbial. So that's the diets with the plus sign in the DFM row.

In the corn-soybean meal diet, the soluble dietary fiber concentration was
approximately 0.9%, whereas in the high fiber diets, it was approximately 1.8%.
Insoluble dietary fiber concentration in the corn-soybean meal diets were
approximately 7% less compared with the high fiber diets, indicating that as we
add 30% DDGS and 10% wheat middlings to the high fiber diet, we increase the
concentrations of soluble and insoluble dietary fiber.

There were six experimental periods, and each period lasted 14 days. And this
included a 5-day adaptation period to the diets, a 5-day total collection of
feces and urine, following the marker to marker approach, so that's day 5 to day
11, and then on days 13 and 14, ileal digesta was collected for 8 hours on each
day.

Six pigs were allotted to each treatment. On this slide, we are looking at
Treatment 1, where all pigs were fed a standard corn-soybean meal diet for all
six periods. This was done so that we could determine the baseline measurement
of feeding a low fiber corn-soybean meal diet over a period of 12 weeks.

Treatment 2 pigs were fed the corn-soybean meal diet in period 1, but then in
periods 2, 3, and 4, pigs were fed the corn-soybean meal plus DFM diet. And
then, in periods 5 and 6, the DFM was withdrawn from the corn-soybean meal diet
and pigs were fed the corn-soybean meal diet without the DFM. This was done to
determine if any carryover effects exist due to DFM supplementation.

Treatment 3 pigs, again, were fed the corn-soybean meal diet in period 1 to
establish baseline measurements, but then in periods 2, 3, and 4, pigs were fed
the high fiber diet for that period of six weeks. Once again, in periods 5 and
6, the high fiber diets were withdrawn, and pigs were fed the corn-soybean meal
diets to determine if any carryover effects of feeding a high fiber diet for a
period of six weeks exists when pigs are switched back over to a standard
corn-soybean meal diet.

And finally, treatment 4 pigs were fed the corn-soybean meal diet in period 1,
but then in periods 2, 3, and 4, pigs were fed the high fiber diet plus the
direct fed microbial. And then once again, in periods 5 and 6, pigs were fed the
corn-soybean meal diet, and the DFM and fiber were withdrawn in order to
determine if there were any carryover effects from feeding the high fiber diet
plus the DFM.

So all pigs in period 1 were fed the corn-soybean meal diet to determine
baseline measurements, and then we could utilize period 1 as a covariate for
when we analyzed periods 2, 3, and 4 using repeated measures analysis to test
the effects of period, fiber level, or DFM.

And finally, in periods 5 and 6, pigs were fed the corn-soybean meal diet in
order to determine if any carryover effects exist from the diet that was fed for
a period of 6 weeks, from periods 2 through 4.

Now, we'll move into the results and discussion for this experiment.

We will begin with focusing on results for treatment 1 and treatment 2 over the
six experimental periods. Remember, treatment 1 pigs were fed the corn-soybean
meal diet for all six periods, whereas treatment 2, the DFM was added to the
corn-soybean meal diet in periods 2, 3, and 4.

The apparent ileal digestibility of starch in treatment 1 pigs is shown in this
graph. Periods increased from period 1 in blue on the left of the graph to
period 6 in the orange bar on the right of the graph. And we utilized orthogonal
polynomial contrasts within each treatment to determine statistical significance
of each experimental period. We observed that periods 2 through 4 had a tendency
to have a greater AID of starch compared with period 1. We also observed that
periods 5 and 6 had a greater apparent ileal digestibility of starch compared
with period 1. This indicates that over that 12-week period, the apparent ileal
digestibility of starch by pigs increased from 93 to 97% in a standard
corn-soybean meal diet.

Now, we are looking at a graph of the treatment 2 pigs' apparent ileal
digestibility of starch. Remember that treatment 2 pigs were fed the
corn-soybean meal diet plus the DFM in periods 2, 3, and 4. So the pink, green,
and red bars. We observed that periods 2 through 4 had a greater AID of starch
compared with period 1. But we also observed that periods 5 and 6 had a greater
AID of starch compared with period 1, indicating that again, as was observed for
treatment 1 pigs, the apparent ileal digestibility of starch increased over
time, and that the addition of the direct fed microbial to periods 2, 3, and 4
to the corn-soybean meal diet did not increase the AID of starch; rather, the
pig adapted over time and was able to increase the apparent ileal digestibility
of starch in the corn-soybean meal diet.

We observed that the apparent ileal digestibility of lysine was not different
amongst the experimental periods for pigs fed treatment 1, the corn-soybean meal
diet throughout the six periods. These results are in agreement with previous
research by Stewart and others, published in 2010 in the Journal of Animal
Science, that was also conducted in the Stein Monogastric Nutrition Laboratory.
And therefore, we can confirm that the apparent ileal digestibility of lysine
and most amino acids in a corn-soybean meal diet do not change over 6
experimental periods, or 12 weeks' time.

However, we did observe that the apparent ileal digestibility of lysine in
periods 2 through 4, where pigs were fed the corn-soybean meal plus the direct
fed microbial, was increased compared with period 1 as well as compared to
periods 5 and 6. And periods 5 and 6 were not different compared with period 1.
These results indicate that the direct fed microbial increased the apparent
ileal digestibility of lysine from 85 to approximately 87.5% in periods 2
through 4. And then, when the DFM was withdrawn from the corn-soybean meal diet,
the apparent ileal digestibility of lysine was reduced back to what it was in
period 1, and therefore no carryover effects exist from feeding the direct fed
microbial and it is concluded that the direct fed microbial must be continuously
fed.

Now, we'll move into the results for treatment 3 and treatment 4, where the high
fiber diet or the high fiber diet plus DFM was fed in periods 2, 3, and 4.

We observed that the apparent ileal digestibility of starch was greater in
periods 2 through 4, where the high fiber diet was fed, compared with period 1.
This indicates that the apparent ileal digestibility of starch in a high fiber
diet is not reduced due to the addition of DDGS or wheat middlings. These
results make sense, because the contribution of starch from DDGS and wheat
middlings to this corn-soybean meal diet is fairly low. And therefore, most of
the starch contribution in the high fiber diet is still coming from corn, and we
observed previously that the digestibility of starch in the corn-soybean meal
diet increased over time, and therefore we observe a similar response here with
treatment 3 pigs.

Also, in agreement with our previous results, pigs fed the high fiber diet plus
the direct fed microbial in periods 2 through 4 had increased AID of starch
compared with period 1, but when the high fiber diet and the DFM were withdrawn
and pigs were fed the corn-soybean meal diet in periods 5 and 6, the AID of
starch was greater compared with period 1 and was not different compared with
periods 2 through 4, indicating that the apparent ileal digestibility of starch
increased over time over the 6 experimental periods regardless of diet type or
the addition of the direct fed microbial.

We observed that the apparent ileal digestibility of lysine was reduced in
periods 2 through 4 when pigs were fed the high fiber diet compared with period
1 and periods 5 and 6. And periods 5 and 6 were not different compared with
period 1. The reduction in the apparent ileal digestibility of lysine in the
high fiber diets may be attributed to the fact that DDGS and wheat middlings
contain greater concentrations of lysine and have lower digestibilities of
lysine, and therefore the digestibility of the high fiber diet is reduced
compared with our corn-soybean meal diets that were fed in period 1 and periods
5 and 6. This also indicates that when the high fiber diet is withdrawn and the
corn-soybean meal diet is fed, digestibility values of lysine are improved to
what was observed in period 1, and that no negative carryover effects on the AID
of lysine are observed when feeding the high fiber diet and then switching pigs
back to a standard corn-soybean meal diet.

The addition of the direct fed microbial to the high fiber diets in periods 2
through 4 did not ameliorate the negative effect that the high fiber diet had on
the apparent ileal digestibility of lysine. And therefore, the AID of lysine in
periods 2 through 4 were less compared with period 1 and periods 5 and 6. And
again, no carryover effects of the high fiber diet plus DFM were observed.

Now, we will move into the results where we utilized repeated measures analysis
during periods 2, 3, and 4 to test the main effects of fiber level, the addition
of the direct fed microbial, and experimental period on the apparent ileal
digestibility of starch, the apparent total tract digestibility of neutral
detergent fiber, and digestible energy.

First, let me take a moment to set up this slide. On the x axis, we have
experimental periods 2, 3, and 4. The orange bars are our corn-soybean meal
diets, our green bars are our high fiber corn-soy-DDGS-wheat middlings diets,
and the dotted bars are diets that contained the direct fed microbial. We
observed that the apparent ileal digestibility of starch increased from period 2
to period 4 as the pig was fed their respective diets. We did not observe any
effect of fiber or DFM on the apparent ileal digestibility of starch.

Now, we will move back into results from treatment 1, where pigs were fed the
corn-soybean meal diet throughout the 6 experimental periods, and treatment 2,
where pigs were fed the corn-soybean meal diet with the direct fed microbial in
periods 2 through 4, and look at the effects over time on the apparent total
tract digestibility of neutral detergent fiber, and digestible energy.

The apparent total tract digestibility of NDF was greater in periods 5 and 6
compared with periods 2 through 4 and period 1. However, it was that sixth
experimental period that had the substantial increased in the apparent total
tract digestibility of NDF, that induced this statistical effect. Therefore, we
conclude that pigs fed a corn-soybean meal diet over 6 experimental periods only
had an increase in apparent total tract digestibility of NDF at about the
twelfth week. And NDF digestibility was fairly stable from 69 to 70% over the
other 5 experimental periods. And therefore, we conclude that our hypothesis was
incorrect, and that the apparent total tract digestibility of NDF does not
substantially increase over a 12-week period of time when pigs are fed a
standard corn-soybean meal diet.

For pigs fed the corn-soybean meal plus the DFM in periods 2 through 4, we
observed a reduction in the ATTD of NDF compared with pigs fed the corn-soybean
meal diet without t DFM in period 1 and periods 5 and 6. We also observed that
the ATTD of NDF in periods 5 and 6 was not different compared with period 1,
indicating that no carryover effects exist from the addition the direct fed
microbial to the corn-soybean meal diet in periods 2 through 4.

Pigs fed the corn-soybean meal diet for all 6 experimental periods had an
increased digestible energy in kcal/kg in periods 2 through 4 compared with
period 1, periods 5 and 6 compared with periods 2 through 4, as well as compared
with period 1, indicating that over the course of 12 weeks, pigs fed a
corn-soybean meal diet had an increase in digestible energy. The increase in
digestible energy is attributed to the increase in the apparent ileal
digestibility of starch over the 12-week experimental period. This is in
contrast to our hypothesis that fiber digestibility would increase over the 6
experimental periods and therefore would increase digestible energy. But rather,
it was an increase in the apparent ileal digestibility of starch that was
attributed to the increased digestible energy over the 12-week experiment.

We observed that the digestible energy in pigs allotted to treatment 2 did not
increase over the 6 experimental periods. This may be attributed to the addition
of the direct fed microbial in periods 2 through 4. And perhaps the DFM
increased DE ever so slightly; this may have made it more difficult to
distinguish the statistical increase from 3,398 kcal/kg DE in period 1 to the
3,447 kcal/kg DE in period 6.

Now, we will move into results from pigs allotted to treatment 3 and treatment
4, where pigs were fed the high fiber diet or the high fiber diet plus DFM in
periods 2 through 4.

We observed that pigs fed the high fiber diet during periods 2 through 4 had a
reduced ATTD of NDF compared with pigs fed the corn-soybean meal diet in period
1 and periods 5 and 6, indicating that the addition of DDGS and wheat middlings
to the corn-soybean meal diet reduced the ATTD of NDF, which may be attributed
to the lower digestibility of NDF in both DDGS and wheat middlings compared with
corn and soybean meal. No carryover effect on the apparent total tract
digestibility of NDF was observed when the high fiber diet was withdrawn and
pigs were switched back over to the corn-soybean meal diet in periods 5 and 6.

The addition of the direct fed microbial to the high fiber diets in periods 2
through 4 did not improve the apparent total tract digestibility of NDF to that
of the corn-soybean meal diet that was fed in period 1 and periods 5 and 6.

We observed that the digestible energy in period 1 and periods 5 and 6 was
greater compared with periods 2 through 4 where pigs were fed the high fiber
diet. This was expected because the high fiber diet was formulated to contain
less digestible energy compared with the corn-soybean meal diet. We also
observed that periods 5 and 6 had a greater DE compared with period 1, where
pigs were fed the corn-soybean meal diet, indicating that digestible energy
continued to increase throughout the experiment.

We observed that the digestible energy was not improved in periods 2 through 4
to that of period 1 and periods 5 and 6, and we conclude that the addition of
the direct fed microbial to the high fiber diet did not ameliorate the negative
effects of adding DDGS and wheat middlings to a corn-soybean meal diet on the
digestible energy concentration of those diets.

Finally, we'll move into results for periods 2, 3, and 4, again, where we tested
the effects of fiber level, direct fed microbial addition, and period on the
apparent total tract digestibility of NDF and digestible energy.

We observed that the apparent total tract digestibility of neutral detergent
fiber was reduced when pigs were fed high fiber diets compared with pigs fed the
corn-soybean meal diets. We observed no effect of period or DFM on the ATTD of
NDF, indicating that the ATTD of NDF does not change over time and that a 5-day
adaptation period that was utilized in period 2 resulted in similar ATTD of NDF
values for corn-soybean meal or high fiber diets compared with period 4, where
pigs would have had a 33-day adaptation period to the diets.

We observed that the DE increased in period 2 to period 4 as pigs were fed the
corn-soybean meal diet, the corn-soybean meal plus DFM, the high fiber diet, or
the high fiber plus DFM diet. We attribute this increase in DE over time to the
increase in apparent ileal digestibility of starch that was observed over time.
It was also observed that the high fiber diets had reduced digestible energy
compared with the corn-soybean meal diets, but again this was expected because
the high fiber diets were formulated to contain less DE than the corn-soybean
meal diets. Also, the addition of the DFM to the corn-soybean meal or the high
fiber diet had no effect on the concentration of digestible energy.

In conclusion, we observed that the high fiber diets had a decreased apparent
ileal digestibility of lysine and apparent total tract digestibility of ADF and
NDF. However, the apparent ileal digestibility of starch was not affected.

The addition of the 3-strain Bacillus-based DFM to the low fiber diet, or the
corn-soybean meal diet, increased the AID of lysine.

And finally, we observed that the apparent ileal digestibility of starch
increased over time regardless of diet type or DFM addition, and therefore,
digestible and metabolizable energy increased over time.

We'd like to acknowledge Danisco Animal Nutrition-DuPont Industrial Biosciences
for funding this research.

And thank you for listening to this edition of the Stein Monogastric Nutrition
Group's podcast.