Slide 1
Hello. My name is Ferdinando Almeida and I am a Ph. D. student at the 
Hans Stein Monogastric Nutrition Laboratory here at the University of 
Ilinois. Today, I will be presenting the effects of a novel phytase on 
phosphorus digestibilty in corn-soybean meal diets fed to weanling and 
growing pigs.

Slide 2
The outline of this presentation will be as follows: introduction, 
objectives, Experiments 1 and 2, overall conclusions from both 
experiments, and finally some implications of our research.

Slide 3
Swine manure is rich in phosphorus because most of the phosphorus in 
organic sources, such as corn and soybean meal, is bound to the phytate 
molecule. This figure on the right shows the phytate molecule which is 
formed by six carbons (represented in yellow) that can bind up to six 
molecules of phosphate (represented in brown, green, and white). Because 
pigs lack the enzyme that hydrolyzes the phytate molecule, most of the 
phosphorus present in organic sources is unavailable to the pigs. 
Therefore, inorganic phosphorus in the form of monocalcium phosphate or 
dicalcium phosphate needs to be added to the diets to meet the pig's 
requirement of phosphorus. This practice, however, has become expensive, 
and it is not uncommon to observe an oversupply of inorganic phosphorus 
in diets fed to weanling pigs, which is one of the causes for the large 
amount of phosphorus excreted in swine manure.

Slide 4
For this reason, regulations that limit the amount of phosphorus that 
can be applied on the fields have been created. This has led researchers 
to find solutions to improve phosphorus utilization by pigs, and 
consequently reduce phosphorus excretion.

Slide 5
One way of doing it is to add exogenous phytase to the diets. Phytases 
are the enzymes responsible for the hydrolysis of the phytate molecule. 
During hydrolysis of the phytate molecule, the phosphates that were 
bound to the molecule are released into the small intestine, and then 
they are absorbed by pigs. Commercially available phytases can be 
produced from fungi or bacteria, and they are classified as 3-, 5-, or 
6-phytases depending on the carbon position where they start the 
hydrolysis of the phytate. For example, if a phytase starts the 
hydrolysis at carbon #3 in the phytate molecule, this is called a 
3-phytase. So, phytases are widely used, as they are an efficient 
approach to improve phosphorus digestibility and therefore reduce 
phosphorus excretion.

Slide 6
There are several phytases commercially available and new phytases are 
constantly being developed. DSM Nutritional Products has developed a new 
phytase called Ronozyme HiPhos. This is a 6-phytase, which is derived 
from bacteria and expressed in Aspergillus oryzae. This enzyme is not 
yet available commercially and there are no data on the effects of 
Ronozyme HiPhos on the apparent total tract digestibility of phosphorus 
in corn-soybean meal diets fed to pigs.

Slide 7
Therefore, the objectives of these experiments were: first, to test the 
effects of a novel bacterial 6-phytase on the apparent total tract 
digestibility of phosphorus in corn-soybean meal diets fed to weanling 
and growing pigs; and second, to determine minimum amounts of phytase 
needed to optimize the apparent total tract digestibility of phosphorus.

Slide 8
Moving now to Experiment 1...

Slide 9
For the materials and methods, we formulated six corn-soybean meal 
diets. There was a positive control diet with 0.86% calcium and 0.66% 
phosphorus. This diet contained dicalcium phosphate as an inorganic 
source of phosphorus, and corn and soybean meal as organic sources of 
phosphorus. The negative control diet contained 0.48% calcium and 0.36% 
phosphorus and this diet contained only organic sources of phosphorus: 
corn and soybean meal. In addition to these two diets, we formulated 
four diets that were the negative control plus four levels of phytase. 
These levels were 500, 1000, 2000, and 4000 phytase units (FYT)/kg. And 
once again, the enzyme that we used was Ronozyme HiPhos from DSM.

Slide 10
Forty-eight weanling pigs were used in a randomized complete block 
design with eight pigs per treatment. They were placed in metabolism 
cases that were equipped with a nipple drinker and a feeder. Water was 
available at all times and feed was provided twice daily. These cages 
were also equipped with a screen that goes underneath the floor, as 
shown on this picture on the right, which allowed for the total 
collection of feces.

Slide 11
For the statistical analysis, we used the PROC MIXED of SAS, and the 
model included treatment as a fixed effect, and block as a random 
effect. There was no effect of block, and therefore block was removed 
from the final model. We also conducted polynomial contrasts in which we 
compared the positive control versus negative control diets, and we also 
tested the linear and quadratic effects of adding graded levels of 
phytase to the negative control diet. In addition to that, we conducted 
a least squares broken-line analysis to determine the minimum amount of 
phytase needed to maximize the apparent total tract digestibility of 
phosphorus.

Slide 12
Looking at the results now...

Slide 13
This first graph shows the apparent total tract digestibility of 
phosphorus. On the y-axis, we have apparent total tract digestibility of 
phosphorus on a percentage basis. The yellow bar represents the positive 
control diet, the orange bar represents the negative control diet, the 
maroon bar represents the negative control plus 500 FYT/kg, the bright 
red represents negative control plus 1000 FYT/kg, the dark green 
represents negative control plus 2000 FYT/kg, and the bright green 
represents negative control plus 4000 FYT/kg. As we expected, the 
apparent total tract digestibility of phosphorus was greater in the 
positive control diet than in the negative control diet -- 60 versus 40 
percent. We observed that adding graded levels of phytase to the 
negative control diet improved the apparent total tract digestibility of 
phosphorus linearly and quadratically from 40 to 70 percent in the 
negative control diet plus 4000 FYT/kg.

Slide 14
Results from the broken-line analysis indicate that the apparent total 
tract digestibility of phosphorus reached a maximum of 68.4% at a 
phytase level of 1016 FYT/kg.

Slide 15
Now let's look at Experiment 2.

Slide 16
For the materials and methods, we formulated six corn-soybean meal diets 
as we did for Experiment 1. With the exception that in Experiment 2, the 
positive control diet contained 0.79% calcium and 0.56% phosphorus, and 
the negative control diet contained 0.58% calcium and 0.33% phosphorus. 
The levels of phytase added to the negative control diet were the same 
as in Experiment 1 -- 500, 1000, 2000, and 4000 FYT/kg.

Slide 17
For this experiment, we used 24 growing pigs in a 2-period changeover 
design. In Period 1, pigs had an initial body weight of 36.2 kg, and in 
Period 2, pigs had an initial body weight of 47.3 kg.

Slide 18
For the statistical analysis, we used the PROC MIXED of SAS, and the 
model included treatment and period as fixed effects, while block was 
the random effect. There were no effects of period and block, and 
therefore they were sequentially removed from the final model. Once 
again, we used polynomial contrasts to compare the positive control 
versus the negative control diets, and we also tested the linear and 
quadratic effects of adding graded levels of phytase to the negative 
control diet. We also conducted a least square broken-line analysis to 
determine the minimal amount of phytase that is necessary to maximize 
the apparent total tract digestibility of phosphorus.

Slide 19
Now, moving on to the results...

Slide 20
This graph has the same pattern as the graph for Experiment 1. The 
results show that the apparent total tract digestibility of phosphorus 
was greater for the positive control diet than for the negative control 
diet, as we expected. We also observed that the apparent total tract 
digestibility of phosphorus was improved linearly and quadratically as 
phytase was added to the negative control diet. While the apparent total 
tract digestibility of phosphorus for the negative control diet was 40%, 
the apparent total tract digestibility of phosphorus for the negative 
control diet containing 4000 FYT/kg was 72%.

Slide 21
Results from the broken-line analysis indicate that the apparent total 
tract digestibility of phosphorus reached a maximum of 69.1% at a 
phytase level of 801 FYT/kg with no further improvements at any level 
above 801 and below 4000 FYT/kg.

Slide 22
For the overall conclusions, Ronozyme HiPhos was effective in improving 
the apparent total tract digestibility of phosphorus in both weanling 
and growing pigs.  Inclusion levels between 800 and 1000 FYT/kg were 
able to maximize the apparent total tract digestibility of phosphorus.

Slide 23
Although our objective was not to compare weanling versus growing pigs, 
our results showed that the effects of adding graded levels of Ronozyme 
HiPhos to corn-soybean meal diets were very similar, which indicates 
that the effects of adding this enzyme to corn-soybean meal diets fed to 
pigs with a body weight anywhere between 14 and 47 kg should be the 
same. This observation is in agreement with the fact that in Experiment 
2, there was no effect of period on the apparent total tract 
digestibility of phosphorus. And it is also in agreement with previous 
data published in 1999 where body weight also had no effect on 
phosphorus digestibility.

Slide 24
For the implications, phytase definitely increases phosphorus 
digestibility in corn-soybean meal diets. Ronozyme HiPhos can be 
effectively supplemented to corn-soybean meal diets, and we should 
expect to see an improvement in phosphorus utilization by pigs as well 
as a reduction in phosphorus excretion.

Slide 25
I would like to acknowledge DSM Nutritional Products for funding this 
project and I would like to thank you for your attention. If you need 
more information, please visit our website that appears on the screen.