Comparative digestibility of energy and nutrients in diets fed to sows and growing pigs


Hi, my name is Jessica Lowell. I recently
completed my Master’s degree with Dr. Stein in swine nutrition. I’ll be talking about
comparative digestibility of energy and nutrients in diets fed to gestating sows and growing
pigs. Here’s the outline for the presentation. I’ll
start with an introduction, followed by materials and methods. I’ll then go over results and
discussion with a brief summary of results, and then leave you with some overall conclusions. Previous research from Europe has determined
that there are differences in digestibility between gestating sows and growing pigs. And
Europe uses two values for energy – one for gestating sows and one for growing pigs.
One of the main differences between gestating sows and growing pigs is the sow’s superior
ability to ferment fibrous material in the hindgut. Use of high fiber ingredients is
increasing in the United States; however, to our knowledge, there are no data comparing
energy digestibility of gestating sows to growing pigs from North America. Now I will discuss some factors which influence
differences in digestibility and fermentability between gestating sows and growing pigs. The
first factor is body weight. As body weight increases, so does intestinal volume and digestive
capacity. A second factor is hindgut development. A fully developed hindgut supports a greater
microbial mass. Also, fermentative capacity is increased as hindgut development progresses. A third factor which influences differences
in digestibility and fermentability between gestating sows and growing pigs is the level
of feeding. One of the main differences between gestating sows and growing pigs is the level
at which they are fed. Gestating sows are limit fed, and growing pigs are fed ad libitum.
Limit feeding decreases the rate of passage, which causes an increase in absorptive capacity.
Finally, a fourth factor is adaptation to the diets. This is especially important when
talking about added fiber to the diet. It has been determined that the size of the digestive
tract increases with prolonged feeding of fibrous diets. It has also been determined
that the microbial population in the hindgut increases with increased levels of fiber in
the diet. The objective of this study was to determine
if values for apparent total tract digestibility of energy and nutrients, and the digestible
and metabolizable energy of diets, are greater in gestating sows fed 1.5 times maintenance
than growing pigs fed 3.4 times maintenance. Moving on to materials and methods – Eleven
diets were used. Three diets included cereal grains: corn, wheat, and sorghum. Four diets
contained common protein sources: soybean meal, canola meal, distillers dried grains
with solubles, and low fat distillers dried grains with solubles. And the final four diets
included high fiber ingredients: corn germ meal, corn bran, wheat middlings, and soybean
hulls. And the abbreviations you see here in white will be the same abbreviations used
throughout the rest of this presentation. Here is the composition of experimental diets.
And I’ll take a moment to set up the slide. On the X axis is diet, and on the Y axis is
percent inclusion. The blue represents vitamins and minerals included in each diet at about
3%. The three grain diets consisted of corn, wheat, and sorghum included at about 97%,
with no added protein sources. Corn was then used as the grain source for the other eight
diets. We used 88 gestating sows, parity 2 to 6,
and 88 growing barrows with an average initial body weight of 40 kg. The experiment was a randomized complete block
design, with 8 blocks of 11 sows, and 4 blocks of 22 growing pigs, resulting in 8 replicates
per treatment. Sows and pigs were housed individually and
adapted to their diets for 14 days before they were moved into metabolism crates. Sows
were fed at 1.5 times maintenance, and growing pigs were fed at 3.4 times maintenance. Once
moved into metabolism creates, they were adapted for five days before the first marker was
fed, and then feces and urine were collected for four days using the marker to marker approach. Results were analyzed using the Mixed procedure
of SAS. We analyzed the three grain diets, the four protein diets, and the four high
fiber diets separately from one another. Fixed effects were diet, physiological state, and
diet x stage interaction, with random effect as block. Moving on to results and discussion. First, I will discuss results for the apparent
total tract digestibility of crude protein. I will begin with the three grain diets, and
I will take a moment to set up the slide. On the X axis is diet, and on the Y axis is
unit. The dark orange bars represent gestating sows, and the light orange bars represent
growing pigs. The format of the slides will remain the same throughout the rest of this
presentation. We observed differences in apparent total tract digestibility of crude protein
among all three diets. However, overall, gestating sows had greater apparent total tract digestibility
of crude protein compared with growing pigs. Now, looking at apparent total tract digestibility
of crude protein for the four protein diets, again, there were differences among the four
diets in apparent total tract digestibility of crude protein. However, overall, gestating
sows had greater apparent total tract digestibility of crude protein compared with growing pigs. Finally, moving on to the four high fiber
diets, again, we observed differences in apparent total tract digestibility of crude protein
among all four diets. However, overall, gestating sows had greater
apparent total tract digestibility of
crude protein compared with growing pigs. Now I will discuss results for apparent total
tract digestibility of NDF. We observed a diet x stage interaction for
apparent total tract digestibility of NDF. Gestating sows had greater apparent total
tract digestibility of NDF compared with growing pigs for the corn diet. However, gestating
sows had decreased apparent total tract digestibility of NDF compared with growing pigs for the
wheat diet. Gestating sows and growing pigs did not differ in apparent total tract digestibility
of NDF for the sorghum diet. Next, looking at the four protein diets, we
again observed a diet x stage interaction. Gestating sows had less apparent total tract
digestibility of NDF compared with growing pigs for the canola meal diet. However, gestating
sows had greater apparent total tract digestibility of NDF compared with growing pigs for the
conventional DDGS diet. Gestating sows and growing pigs did not differ in apparent total
tract digestibility of NDF for the soybean meal diet or the low fat DDGS diet. Finally, we also had a diet x stage interaction
for the four high fiber diets. Gestating sows had greater apparent total tract digestibility
of NDF compared with growing pigs for the soybean hulls diet. However, gestating sows
and growing pigs did not differ in apparent total tract digestibility of NDF for the corn
germ meal diet, the corn bran diet, or the wheat middlings diet. To summarize the results for apparent total
tract digestibility of NDF – Apparent total tract digestibility of NDF varies between
gestating sows and growing pigs. We are not entirely sure what causes this variation;
however, previous research by Fernandez and others in 1986 also indicates variation in
fiber digestibility between gestating sows and growing pigs. Now I will discuss results for digestible
energy on a dry matter basis. First, looking at the three grain diets, wee
observed differences in digestible energy among the three diets. However, overall, gestating
sows had greater digestible energy compared with growing pigs. Moving on to the four protein diets, digestible
energy differed among the four diets; however, overall, gestating sows had greater digestible
energy compared with growing pigs. We saw a diet x stage interaction for the
four high fiber diets. Gestating sows had greater digestible energy on a dry matter
basis compared with growing pigs for the wheat middlings diet and the soybean hulls diet.
Gestating sows and growing pigs did not differ in digestible energy on a dry matter basis
for the corn germ meal diet or the corn bran diet. To summarize results for digestible energy
– Gestating sows had greater digestible energy compared with growing pigs. And this
is supported by previous research. Results for digestible energy indicate that differences
are not due to differences in fermentation of fiber. Instead, these differences could
be related to differences in digestibility of crude protein and possibly starch. Based on our results, we were able to generate
a prediction equation for digestible energy of sows from growing pigs. This equation had
a relatively good r-squared value and may be used to predict digestible energy for gestating
sows from growing pigs. In the future, additional diets and models could be used to verify this
equation. Moving on to overall conclusions – Apparent
total tract digestibility of energy and nutrients, and digestible energy and metabolizable energy,
are greater in gestating sows fed 1.5 times maintenance compared with growing pigs fed
3.4 times maintenance. However, apparent total tract digestibility of ADF and NDF does not
differ between gestating sows and growing pigs. With that, I would like to thank both the
National Pork Board and Poet Nutrition for their financial support. I would also like to thank the Stein Monogastric
Nutrition Lab for all of their help during this research.

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