Hello, everyone. Today I will talk about the bioavailability of valine in a fermentation
biomass product relative to the bioavailability in crystalline L-valine when fed to
weanling pigs.

Formulated low crude protein diets often makes it necessary to include crystalline amino
acids in the diet. And by supplementing diets with crystalline amino acids, it is possible
to maintain the growth performance in pigs fed diets with reduced crude protein. Valine is
an indispensable amino acid which, along with leucine and isoleucine, belongs to the group
of branched-chain amino acids. And the dietary branched-chain amino acids are primarily
used for synthesis of proteins. In weanling pigs, valine is usually the fifth limiting
amino acid in corn and soybean meal diets.

Therefore, in diets formulated by corn and soybean meal, if valine is deficient, there is
a reduced efficiency of muscle deposition. And to maximize the deposition of muscle,
dietary valine supplementation may be needed to meet the requirement.

Feed-grade L-valine, which contains 98% of valine, is currently available for the feed
industry and the primary source of supplemental valine included in commercial diets for
pigs. Conventional crystalline L-valine is produced by harvesting L-valine from the
fermentation biomass. However, feed-grade L-valine may also be produced by spray-drying
the entire biomass, which will result in a final product contained 64.6% L-valine. It is
expected that the bioavailability of valine in the fermentation biomass is similar to that
in L-valine. But this hypothesis has not been reported.

And therefore, we wanted to conduct this study to test the hypothesis that valine from a
valine-fermentation biomass has a bioavailability of 100% relative to L-valine when fed to
weanling pigs.

Moving on to materials and methods. This experiment used 224 weanling pigs allotted to the
7 diets and 8 replicate pens per diet with 4 pigs per pen. Pigs were fed for 20 days.
Individual pigs’ weights were recorded at day 0 and at the last day of the experiment, and
daily feed allotments were also recorded. Therefore, data for average daily gain, average
daily feed intake, and gain to feed ratio for each diet were calculated. On the last day
of the experiment, a blood sample from one pig in each pen was collected to analyze for
blood urea nitrogen and concentration of plasma free amino acids.

A total of 7 diets were formulated. Diets were based on corn, DDGS, corn gluten meal, and
soybean meal. A valine-deficient basal diet was formulated. And three diets were
formulated by adding 0.08, 0.17, and 0.25% of crystalline L-valine to provide a total
valine in diets of 0.79, 0.88, and 0.98%. We had three additional diets that were
formulated by adding 0.12, 0.25, and 0.37% of valine-fermentation biomass to provide a
total valine in diets of 0.8, 0.85, and 0.96%, respectively.

Moving on to the results…

This graph shows the average daily gain for pigs fed diets supplemented with either
L-valine or valine-fermentation biomass. The average daily gain increased as both sources
were included in the diets. And moreover, pigs fed diets supplemented with
valine-fermentation biomass had a greater average daily gain than pigs fed diets
supplemented with L-valine. The greater average daily gain in valine-fermentation biomass
may be a result of the presence of components other than valine in the biomass. The
valine-fermentation biomass also contains about 13.6% additional essential and
non-essential amino acids. 

This graph shows the results for gain to feed ratio. As a consequence of the previous
results, the gain to feed ratio increased as the source of valine increased in the diets.
However, we did not observe difference for gain to feed ratio between crystalline L-valine
and valine-fermentation biomass. 

Pigs fed diets supplemented with either L-valine or valine-fermentation biomass increased
the final body weight compared with pigs fed the basal diet. Moreover, the final body
weight was also greater for pigs fed diets supplemented with valine-fermentation biomass
compared with crystalline L-valine. The differences for body weight among of the
supplementation levels were 0.2, 0.6, and 0.8 kg more for pigs fed diets supplemented with
valine-fermentation biomass.

This graph shows the results for blood urea nitrogen. The BUN concentration was reduced as
either L-valine or valine-fermentation biomass was included to the basal diet. However, no
difference was observed in BUN between the 2 sources. The reduced concentration of BUN
means that protein synthesis has increased in the pigs. 

This graph shows the plasma free valine in pigs fed with L-valine and valine-fermentation
biomass. The plasma free valine increased as the source of valine was included to the
basal diet. And the increased valine concentration was expected and indicated that valine
provided from both sources was efficiently absorbed from the gastrointestinal tract.

Based on these data, a linear regression was developed to determine relative
bioavailability of valine in valine-fermentation biomass using the crystalline L-valine as
the standard. This graph shows the relative bioavailability for average daily gain, in
which the equation shows that 126 is the common intercept, 409 is the slope of L-valine,
and 597 is the slope of valine-fermentation biomass. The slope ratio was calculated by
dividing the slope of valine-fermentation biomass and the slope of L-valine, multiplied by
100%. With that calculation, we estimate that the relative bioavailability was 146% for
valine-fermentation biomass.

The same way, the equation was developed for gain to feed ratio. Based on this equation,
it was possible to estimate the relative bioavailability for gain to feed ratio in
valine-fermentation biomass was 135%.

Based on that results we presented to you, it was possible to conclude the relative
bioavailability of at least 100% for valine-fermentation biomass relative to L-valine.
Pigs supplemented with valine-fermentation biomass had a greater average daily gain and
final body weight. And therefore, valine-fermentation biomass can be used as a source of
valine in diets for weanling pigs.

With that, I would like to acknowledge Evonik for your financial support in this study.

Also, I would like to thank you for listening to this talk. And if you are interested to
know more about the research that we have been conducting, you can visit our website at
nutrition.ansci.illinois.edu.