Hi everyone. I’m Charmaine Espinosa, a PhD student under Dr. Hans H. Stein.
Today, I will discuss my Master’s thesis conducted at the University of the
Philippines Los Baños, which is the Effect of α-Galactosidase on the Energy
Value of Soybean Meal and Growth Performance of Weanling Pigs.

In this presentation, I’m going to briefly discuss some background about soybean
meal and the oligosaccharides present in it, then I’ll move on to discuss the
two experiments we’ve conducted. First is an energy and nutrient digestibility
study, followed by a nursery growth performance experiment with each one
discussing the materials and methods, results, and then conclusions.

Soybean is the most important and fastest growing agricultural protein crop in
animal feeding. When processed as soybean meal, it is the most widely used plant
source for protein in livestock and poultry feeds because of its excellent amino
acid profile. A nd in terms of production, the United States is the leading
country contributing about 34% of soybean supply in the world.

So this is just an overview of how soybeans are processed. Soybeans are cracked
then dehulled to produce dehulled soybeans. And removal of the hulls is an
important process because it effectively reduces the dietary fiber concentration
in soybean. After the dehulling process, oil from the meal is extracted and this
results to soybean meal which has a higher protein and soluble carbohydrate
concentration compared to soybean.

The carbohydrates present in soybean meal mainly consist of non-starch and
non-structural polysaccharides. Some of these non-structural polysaccharides
consist of free sugars, sucrose, and oligosaccharides. These oligosaccharides
mainly consist of stachyose and fewer concentrations of raffinose and
verbascose, and these cannot be fully digested by young pigs.

This could be attributed to the 1, 2, or 3 α(1-6) linked units of galactose
linked through an α(1-3) bond to a terminal sucrose. And weanling pigs do not
produce significant quantities of α-galactosidase to degrade these bonds. 

A handful of negative effects of these oligosaccharides were shown. These
oligosaccharides have the capability of reducing the efficiency of digestion and
absorption of nutrients which affect growth performance as reflected in the
experiment conducted by Liying and his colleagues in 2003 where addition of 1%
or 2% stachyose significantly reduced average daily gain of nursery pigs. 

Oligosaccharides also undergo fermentation which causes diarrhea as also shown
in this experiment where addition of stachyose increased the percentage of
diarrhea incidence in nursery pigs.

Because of this, a number of methods have been previously studied to reduce the
oligosaccharides present in soybean meal. First is ethanol extraction, that has
been used since the early 90s with the assumption that oligosaccharides are
soluble in ethanol. This results to a soy protein concentrate with greater
nutrient composition and reduced antinutritional factors compared to soybean
meal. Next, is the use of fermentation in the presence of fungal and bacterial
strains to effectively remove antigens and oligosaccharides. The use of enzyme
treatment also results in the reduction of significant amounts of these
antinutritional factors by breaking down oligosaccharides into simple sugars.
Plant breeders have also developed new varieties of soybean meal with low
oligosaccharide concentration. It has been reported that low oligosaccharide
soybean meal has less stachyose and raffinose compared with conventional soybean
meal and could improve average daily gain and carcass yield in broilers. And
finally, the use of exogenous enzymes, in this case, the use of an
α-galactosidase which acts on galactose side chains to reduce the anti-nutritive
effects of oligosaccharides and further increase the energy value of soybean
meal. 

A digestibility study was conducted to determine the effect of increasing levels
of an α-1,6 galactosidase enzyme complex on the metabolizable energy
concentration of soybean meal and apparent total tract digestibility of
nutrients in corn-soybean meal diet.

Pigs were individually penned in metabolism crates equipped with a feeder and
drinker, fully slatted floors, screen floor, and urine trays which allows for
the total but separate collection of urine and fecal materials.

40 barrows were used in this experiment, with 5 experimental diets with 8
replicates per treatment. The 5 diet consist of the corn diet, a corn-soybean
meal diet, corn-soybean meal diet with 100 mg/kg of α-galactosidase, a
corn-soybean meal diet with 200 mg/kg α-galactosidase, and a corn-soybean meal
diet with 400 mg/kg α-galactosidase.

The amount of energy lost in the feces and in the urine were calculated and the
ME concentration in each of the diets were determined. The ME concentration in
soybean meal were calculated by the difference procedure then the ATTD of
nutrients were determined using the total nutrient intake and total fecal output
of pigs from day 6 to day 10.

Let’s move on to the result of this experiment.

This figure shows the ME concentration in corn-soybean meal diets. So upon
supplementation of increasing levels of α-galactosidase, the ME concentration
tended to increase from 3,265 to 3,351 kcal/kg. This suggests that the enzyme
may have hydrolyzed significant quantities of oligosaccharides in soybean meal.

This was also observed in this result by which increasing levels of the enzyme
tended to increase the ME concentration of soybean meal from 3,811 to 4,120
kcal/kg, which means that the enzyme has increased the ME of soybean meal by 300
kcal. The increase in ME concentration provides evidence that the enzyme used in
this experiment is effective in releasing more energy from soybean meal.

Not only did the enzyme increase the energy concentration in soybean meal, but
also increased the ATTD of some nutrients in corn-soybean meal diets. There’s a
tendency for a quadratic improvement in the ATTD of ash, 

and a tendency for a linear improvement in the ATTD of crude fat in corn-soybean
meal diets. It has been shown that oligosaccharides have the capability to
impair interaction of endogenous enzymes with nutrients such as fat and minerals
by forming viscous gels in the animal’s gastrointestinal tract. So with the
enzyme present, this negative effect can be reduced and therefore increase the
ATTD of nutrients.

In this experiment, it has been inferred that addition of increasing levels of
α-1,6-galactosidase enzyme complex increased the ME concentration of soybean
meal by 300 kcal/kg, and increased the ATTD of ash and crude fat in corn-soybean
meal diets.

Now to validate the results that we got in Experiment 1, that the enzyme can
increase the ME concentration of soybean meal and therefore can improve growth
performance, this experiment was conducted.

378 weanling pigs were used with 6 replicates per treatment. Pigs were fed a
common phase 1 diet from day17 to day 35 and the experimental diets were fed
from day 35 to day 45. The first diet served as the control diet with no
α-galactosidase and formulated with soybean meal ME at 3,344 kcal/kg. The next
diet, which is the on-top treatment, was the same as the first diet except that
100 mg/kg of α-galactosidase was added to the diet. The last diet, which is the
matrix treatment, was also supplemented with 100 mg/kg of the enzyme except that
it was formulated with soybean meal ME at 3,644 kcal/kg assuming that the enzyme
can increase the ME concentration of soybean meal by 300 kcal/kg.

In this diet formulation, with the use of the enzyme and its matrix value of 300
kcal/kg, it can reduce the inclusion of fat in the diet from 3% to 1.7%. In this
formulation, we have reduced the use of coconut oil.

Now, let’s move on to the result of this experiment.

This figure shows the average daily gain of pigs used in the experiment. This
shows that pigs on the on-top treatment tended to have greater average daily
gain compared with the control treatment with pigs on the matrix treatment being
the intermediate.

Treatment with the α-galactosidase supplementation had greater total body weight
gain compared with the control treatment, and this improvement may be due to the
additional energy released by the α-galactosidase from soybean meal and
therefore greater energy intake of pigs compared with the control.

There was no difference observed in the average daily feed intake of pigs among
treatments, 

and the same was also observed with the gain to feed ratio, wherein similar
response was observed among treatments.

But in terms of caloric efficiency, pigs fed diets with α-galactosidase tended
to be better than those fed the control diet, which may be due to the improved
utilization of carbohydrates and fats in the diets.

In conclusion, addition of 100 mg/kg of α-1,6-galactosidase enzyme complex
improved growth performance of nursery pigs, and this experiment validates the
result in Experiment 1 that the enzyme increased the ME of soybean meal in
nursery pigs.

Thank you so much for your attention, and I would like to take this opportunity
to thank Dr. Rommel Sulabo and Kerry Feed Ingredients for the funding of this
project.