XII - 12th International Symposium - Digestive Physiology of Pigs

Digestive
Physiology
of Pigs
Glutathione (GSH) serves as a major endogenous
antioxidant in gut tissue and cells keep it predominantly in
the reduced state, i.e., a low oxidized to reduced glutathione
(GSSG/GSH) ratio. Glutathione peroxidase (GSH-Px)
converts GSH to GSSG besides its direct action on other
substrates. The aim of this study was to assess the effect
of birth-weight, sex and days post-weaning on the small
intestinal mucosal glutathione system. Newborns from 17
Danbred hybrid sows were weighed. At weaning (18.8 ±
0.44 d) pairs of intrauterine growth restricted (IUGR) and
normal birth-weight sex-matched littermates were selected
and fed a starter ad lib until 1 h before sampling at 0, 2,
5, 12 and 28 d post-weaning. Mucosa was collected from
2 small intestinal sites; at 5% (≈end of duodenum) and at
75% of total length, to determine GSH and GSSG by HPLC,
GSH-Px spectrophotometrically and malondialdehyde
(MDA), a marker of lipid peroxidation according to the
TBARS method. GSH-Px and MDA were also determined
in plasma. Data were analyzed by linear models. Birthweight
and sex showed no and minor significant effects,
respectively. Both at 5 and 75% of total length, the GSH-
Px activity and GSH concentrations increased gradually
with days post-weaning to peak at d 12. The GSH-Px
activity and GSH concentrations at 5% of total length were
consistently higher as compared with 75% of total length
(e.g., at d 12: 43.2 and 28.9 U/mg protein, and 21.5 and
15.4 μmol/g protein, respectively). The GSSG/GSH ratio at
5% of total length was 2-fold higher at d5 compared with all
other days (P < 0.05), possibly indicating that the mucosal
redox balance was disturbed in that time window. At 75%
of length of the small intestine there was a tendency for
GSSG/GSH to decrease with time. Malondialdehyde was
only significantly affected at 75% of length; after weaning
(2.44 nmol/mg protein) it decreased sharply until d5 (1.17
nmol/mg protein). The higher GSH-Px activity, GSH content
and GSSG/GSH ratio in the proximal small intestine might
illustrate the higher need for antioxidant action against
dietary pro-oxidants at that site. Plasma MDA and GSH-
Px activity followed a comparable pattern as in the small
intestine.
Key words: glutathione, peroxidase, weaning
3054 whole body protein deposition and plasma
amino acid profiles in growing/finishing pigs fed different
levels of sulfur amino acids with and without E.
coli-lipopolysaccharide challenge. J. C. Kim* 1 , B. P. Mullan
1 , B. Frey 2 , H. G. Payne 1 , and J. R. Pluske 3 , 1 Livestock
Innovation, Department of Agriculture and Food, 3 Baron-
Hay Court, South Perth, WA 6151, Australia, 2 Consistent
Pork, East Perth, WA 6004, Australia, 3 School of Veterinary
and Biomedical Sciences, Murdoch University, South
Street, Murdoch, WA 6150, Australia.
A split plot experiment with 72 male pigs weighing 52.9
± 0.39 kg (mean ± SEM) was conducted to examine
amino acid partitioning and body protein deposition
rate in response to increasing dietary sulfur amino acids
(SAA) with and without immune system (IS) activation.
The main plot was with and without IS activation, and 4
diets containing different amounts of standardized ileal
digestible (SID) SAA (SAA to lysine ratios of 0.45, 0.55,
XII INTERNATIONAL SYMPOSIUM ON
DIGESTIVE PHYSIOLOGY OF PIGS
140
Session VII
0.65 and 0.75) were the subplots. Increased SAA was
achieved by increasing the DL-methionine content in the
diet. Pigs were intramuscularly injected with either saline or
E. coli lipopolysaccharides (LPS, serotype 055:B5, Sigma,
30 μg/kg BW) every Monday and Thursday to initiate IS
activation. Blood samples were collected every 2 weeks
and half carcasses were scanned through DXA at the end
of the experiment. Split-plot ANOVA was used for statistical
evaluation. Maximum body protein deposition and minimum
plasma urea content were achieved at SID SAA:Lys ratio
of 0.55 in saline-injected pigs, but were achieved at a
SID SAA:Lys ratio of 0.65 and 0.75, respectively, in LPSchallenged
pigs. The LPS challenge decreased red blood
cell count (P < 0.001) and hemoglobin content (P < 0.05),
and increased the proportion of neutrophils (P < 0.05),
compared with saline injection, while increasing dietary
SAA had no effects on the measured variables. The LPS
challenge decreased most plasma amino acids (P < 0.05 <
P