Hello everyone. My name is Diego Andres Lopez, and I’m a second-year student in Dr.
Stein’s group. Today, I will talk about the research about the effect of microbial phytase
on standardized total tract digestibility of phosphorus in feed phosphates by growing
pigs.

As an introduction, phosphorus is the second most abundant mineral in the body. And it can
be delivered to pigs in two different ways. First, plant ingredients, which have a low
digestibility of phosphorus, and this is due to the presence of a molecule called phytate.
Phytate is the natural storage of phosphorus in the plants, and in order to be broken
down, we need an enzyme called phytase. But this phytase does not occur naturally in the
gastrointestinal tract of the pig. Therefore, this enzyme is also supplemented in diets.
And the second way is using inorganic sources of phosphorus with a high digestibility of
phosphorus. And in this case, the ingredients that we can use are feed phosphates such as
monocalcium phosphate, monosodium phosphate, and magnesium phosphate.

But when we analyze a molecule of phytate, we can also see how this will naturally
interact with other minerals such as calcium, binding up to six molecules of calcium.
However, recent research has indicated that the use of phytase in diets containing calcium
carbonate will increase the digestibility of calcium.

Having this in mind, we conducted an experiment with the objective of testing the
hypothesis that microbial phytase could also increase the digestibility of phosphorus in
feed phosphates.

For this experiment, we used 170 pigs with an average body weight of 15.56 kg. And in this
case, we formulated three basal diets with inclusion of 0, 500, and 4,000 phytase units.
We included one of the three different sources of feed phosphates that we used in this
experiment, which are MCP, MSP, and MGP, to the basal diets. And therefore, we included
twelve diets in this experiment, also a phosphorus-free diet, for a total of 13 diets. The
pigs in this experiment were allotted into these 13 diets, and they were housed
individually in metabolism crates with free access to water and being fed twice a day. In
this experiment, we had an adaptation period from day 1 to day 5. And then, an
undigestible marker was fed to start a collection period on day 6. This collection period
will go until day 10, where they were fed a second undigestible marker, and then they will
be collected until the second undigestible marker passed, which was, on average, until day
12.

First, for the nutrient composition of the ingredients, I would like to set up my slide.
And in this case, MCP will be represented in blue, MSP will be represented in orange, and
MGP will be represented in yellow. For the concentration of phosphorus and calcium, the
results were in agreement with reported data. But in the case of magnesium phosphate, the
concentration of phosphorus was lower than expected. In the case of corn and soybean meal,
the concentration of phosphorus, calcium, and phytate were also in agreement with expected
values.

Moving into the results of digestibility of phosphorus, first, I would like to set up my
slide. You’ll find the basal diets represented in green, the MCP diets represented in
blue, the MSP diets represented in orange, and MGP diets represented in yellow. Also, the
lightest color will represent the inclusion of 0 FTU, the darkest color will represent the
inclusion of 4,000 units of phytase, and the color in the middle will be representing the
500 units of phytase. And as we were expecting, the digestibility of phosphorus in basal
diets increased with the inclusion of phytase, from around 45% to almost 90%. And, if we
analyze the results from MCP diets, what we can observe is an increase in the
digestibility as we increase the inclusion of phytase, but we can also observe a
difference between the basal diet with 0 phytase and the MCP diet with 0 phytase, which
indicates the increase in the available phosphorus when we include a source of inorganic
phosphorus. From MSP, we observe the same results—an increase in the digestibility as we
increase the concentration of phytase. And the same results were observed for MGP.
However, the results from MGP appear to be lower. However, this is the digestibility of
phosphorus in the diets, and the objective of this experiment was to test if the
digestibility of phosphorus in the ingredients is different.

For that reason, we used the difference procedure to analyze the digestibility of
phosphorus in these ingredients. And in this case, blue will represent again the MCP,
orange will represent MSP, and yellow will represent MGP. And what we can observe is that
there was no difference in the digestibility of phosphorus in MCP, MSP, or MGP. The only
difference that we can observe here is that MGP had a lower digestibility if it’s compared
with MCP or MSP.

So, moving into the conclusions, the digestibility of phosphorus in feed phosphates was
not affected by the inclusion of phytase in the diets. The effect that we observed in the
diets is the effect of phytase on the phosphorus present in corn and soybean meal, which
was expected. Also, we can observe that the digestibility of phosphorus, or STTD of
phosphorus, in magnesium phosphate was lower than MCP and MSP.

With that, I would like to acknowledge Yara for the financial support to conduct this
experiment.

And then I would like to say thank you to the Monogastric Nutrition Laboratory of Dr. Hans
Stein. And if you are interested in nutrition, please follow us in our social media. Thank
you for listening.