XII - 12th International Symposium - Digestive Physiology of Pigs

Digestive
Physiology
of Pigs
phytase inclusion numerically decreased the plasma
copper level (P=0.12). The meta-analysis indicated that
500 FTU phytase/kg generated 0.80 g digestible P, 0.75 g
digestible Ca, 2.1 mg digestible Cu and 3.6 mg digestible
zinc. Based on published response studies with different
levels of zinc sulfate in the diet, we estimated that inclusion
of 500 FTU microbial phytase/kg allows a reduction of 20-
40 mg zinc from zinc sulfate/kg. The contribution of phytase
to the dietary copper supply remains inconclusive.
Key words: phytase, zinc, copper
1064 Modelling the retention and excretion of digestible
phosphorus for different genotypes. V. Symeou,* I.
Leinonen, S. Edwards, and I. Kyriazakis, School of Agriculture,
Food and Rural Development, Newcastle University,
United Kingdom.
A model has been developed to enable better match
between digestible phosphorus (dP) supply and retention
in pigs of different genotypes and thus reduce P excretion.
Maintenance dP was modeled as functions of the body
protein mass (Pr) and mature Pr mass (Pr ) to accommodate
m
-0.27 differences in genotypes: 0.1293*Pr*Pr (g/day). This
m
was an advance over the expression of maintenance dP
as a function of live weight. From literature, the efficiency
of dP utilization for retention was estimated at 0.9 and
assumed to be independent of live weight and genotype.
dP retention was found to be isometrically related to Pr
retention: 0.0337*dPr/dt. This allowed the dP retention to
be expressed as simple functions of Pr. However within
an insufficient lysine diet, when the ratio tLysine: Ash was
below 0.45 g/g in the diet, the P: Pr ratio of empty body
weight was estimated: 0.06 - (0.046 x tLysine:Ash diet).
Above the 0.45 threshold, the P: Pr ratio in the body was
constant at 0.0337. The model allows for robust predictions
of dP utilization under different feeding scenarios for pigs
of different genotypes. As BSAS (2003) standard are the
only ones that account for genotype effects on P utilization,
comparisons to our predictions suggest that BSAS (2003)
moderately underestimate the requirements for dP for
intermediate pig genotype, while for the commercial BSAS
(2003) pig genotype the same standards overestimate dP
requirements.
Key words: maintenance phosphorus, phosphorus retention,
efficiency of utilization
1065 Prediction of apparent, standardized and true
ileal digestible total and reactive lysine contents in
heat-treated soybean meal samples. J. C. Kim* 1 , B. P.
Mullan 1 , and J. R. Pluske 2 , 1 Livestock Innovation, Department
of Agriculture and Food, 3 Baron-Hay Court, South
Perth, WA 6151, Australia, 2 School of Veterinary and Biomedical
Sciences, Murdoch University, South Street, Murdoch,
WA 6150, Australia.
An experiment was conducted to establish linear regression
equations to predict apparent, standardized and true ileal
digestible total and reactive lysine content in heat-treated
soybean meal (SBM) samples. Forty-two individually-
XII INTERNATIONAL SYMPOSIUM ON
DIGESTIVE PHYSIOLOGY OF PIGS
64
Session II
housed entire male crossbred pigs weighing 37.5 ± 0.15
kg (mean ± SEM) were used in a randomized block study
with 7 dietary treatments (n = 6). The dietary treatments
were 5 SBM-based semi-synthetic diets containing 350 g/
kg of SBM with variable heat treatments (0, 7, 14, 21, and
28 min autoclaved at 135°C), a protein free (N-free) diet,
and an enzymically-hydrolyzed casein (EHC) diet. Pigs
were randomly allocated to the experimental diets based
on live weight and fed the respective diet for 5 d at 2.5 times
maintenance [2.5 × (0.458 MJ × BW 0.75 )/diet DE]. On d 6,
pigs were euthanized 9 h ± 20 min. from the start of feeding.
Digesta samples were collected within 5 min. of euthanasia
from the ileum 40 cm proximal to the ileo-cecal junction,
and later analyzed for amino acids and the digestibility
marker, titanium dioxide. Ileal samples collected from pigs
fed the EHC diet were ultrafiltered at 10k Daltons. Reactive
lysine content was determined using the homoarginine
method. Standardised and true ileal digestibility were
calculated by adjusting apparent ileal digestibility with the
endogenous amino acid flows determined under N-free
and EHC-ultrafiltration methods, respectively. One-way
ANOVA and polynomial comparison were conducted using
Genstat 12. Heat treatment linearly decreased total lysine
content from 30.4 g/kg to 21.5 g/kg (P < 0.001) and reactive
lysine content from 25.9 g/kg to 13.2 g/kg (P < 0.001).
Apparent, standardized and true ileal digestible total and
reactive lysine contents linearly decreased with increasing
severity of heat treatment (P < 0.001) and were accurately
predictable from total and reactive lysine content in heatdamaged
soybean meals (P < 0.001). The result indicates
that excessive heat processing of SBM reduced both the
content (P < 0.001) and digestibility (P < 0.001) of total and
reactive lysine in SBM.
Key words: soybean meal, reactive lysine, ileal digestibility
1066 Digestible and metabolizable energy concentrations
in copra meal, palm kernel meal, and cassava
root fed to growing pigs. A. R. Son* 1 , S. Y. Ji 2 , and B.
G. Kim 1 , 1 Department of Animal Science and Environment,
Konkuk University, Seoul, Republic of Korea, 2 Animal Nutrition
and Physiology Team, National Institute of Animal Science,
RDA, Suwon, Republic of Korea.
An experiment was conducted to measure DE and ME in
copra meal (CM), palm kernel meal (PKM), and cassava
root (CR). Copra meal contained 88.7% DM, 4,232 kcal
GE/kg, 21.0% CP, 7.5% ether extract, 54.5% NDF, and
6.7% ash; PKM contained 92.6% DM, 4,466 kcal GE/kg,
16.9% CP, 6.7% ether extract, 68.3% NDF, and 4.0% ash;
and CR contained 88.1% DM, 3,556 kcal GE/kg, 4.0% CP,
0.5% ether extract, 19.4% NDF, and 6.8% ash on an as-fed
basis. Eight boars with an initial mean BW of 67.3 kg (SD =
5.8) were individually housed in metabolism crates that were
equipped with a feeder and a nipple drinker. A replicated
4 × 4 Latin square design was employed with 4 dietary
treatments, 4 periods, and 8 animals. A basal diet mainly
contained corn and soybean meal. Three additional diets
were formulated to contain 30% of CM, PKM, and CR. All
diets contained the same proportion of corn:soybean meal
ratio at 4.14:1. The marker-to-marker method was used
for fecal collection with 4-d adaptation and 4-d collection