XII - 12th International Symposium - Digestive Physiology of Pigs

Digestive
Physiology
of Pigs
Perth, Western Australia, Australia, 3 Evonik Industries AG,
Hanau, Wolfgang, Germang, 4 University of Guelph, Guelph,
Ontario, Canada, 5 Nutreco, Boxmeer, The Netherlands.
This experiment examined if a higher ratio of dietary TRP
to LYS (TRP:LYS), in the absence of antimicrobials, would
improve feed conversion efficiency (FCE) and modulate
diarrhea in weaner pigs infected or not infected with
enterotoxigenic E. coli (ETEC). Effect of the TRP:LYS ratio
on plasma levels of TRP and its metabolite kynurenine (KYN)
were also examined, as KYN levels can increase during
inflammation states such as during disease challenge.
Individually housed pigs (n = 72) weaned at 21 d (Landrace
x Large White, mixed sex, mean ± SEM body weight 6.3
± 0.32 kg) were stratified into one of 6 treatments (n = 12)
according to a 2x3 factorial arrangement of (i) infection or
no infection with ETEC and (ii) 3 levels of standard ileal
digestible (SID) TRP:LYS ratios of 0.17, 0.21 or 0.25, in
a randomized complete block design. Pigs were fed diets
(10.4 MJ NE, 1.24% SID LYS, 19.5% CP) ad libitum for 3
weeks after weaning. Pigs were infected with ETEC (6, 8
and 10 mL of 2.12 × 108 cfu/mL, serotype O149:K98:K88)
at 72, 96 and 120 h after weaning and then bled on d 11. A
TRP:LYS ratio of 0.25 improved (P = 0.024) FCE over the
study period compared with other ratios (1.48, 1.48 and 1.35
for 0.17, 0.21 and 0.25, respectively), without an infection
effect. Treatments did not affect daily gain or feed intake (P
> 0.05). Infection increased diarrhea index (P = 0.039) and
deteriorated fecal consistency (FC; P = 0.025). Time and
infection interacted for FC (P = 0.001) and ETEC shedding
as assessed by fecal swabs (FS; P = 0.034), with differences
greatest on d 7 for FC and d 5 for FS. Plasma TRP and KYN
were lower in pigs fed 0.17 TRP:LYS than those fed ratios
of 0.21 and 0.25 (P = 0.001), without an infection effect. In
conclusion, in the absence of antimicrobials, increasing the
dietary TRP:LYS ratio enhanced plasma levels of TRP and
KYN and a ratio higher than 0.21 TRP:LYS improves FCE
in the period after weaning.
Key words: tryptophan, performance, E. coli
1100 Phytase improves apparent fecal P and Ca
digestibility of piglet diets with adequate or reduced P
content. I. Kühn* 1 and K. Partanen 2 , 1 AB Vista, Darmstadt,
Germany, 2 MTT Agrifood Research, Hyvinkää, Finland.
The effect of a thermo-tolerant phytase (Quantum Blue)
on performance and apparent fecal phosphorus (P) and
calcium (Ca) digestibility was evaluated in 192 weaned
piglets (randomized block design, 16 replicates, 2 piglets
each). Wheat, barley, oat, soybean meal and whey-protein
based diets with adequate (PC) or reduced (NC) Ca and
P levels where fed 46 d after weaning. PC and NC diets
contained Ca 8.0 and 6.4 g/kg and digestible P 2.9 and
1.9 g/kg, respectively. Pelleted diets contained 0, 500
or 1000 FTU/kg of phytase. Growth performance and
feed conversion ratio were measured during starter (25
d) and weaner (21 d) periods. Apparent fecal Ca and P
digestibilities were determined by spot-sampling at the
end of the weaner period (8 pens per treatment over 5
consecutive days). The data was analyzed using a mixed
model with random block effect and fixed effect of dietary P
XII INTERNATIONAL SYMPOSIUM ON
DIGESTIVE PHYSIOLOGY OF PIGS
77
Session II
level and phytase addition and their interaction. Dietary P
level did not affect growth performance or feed conversion
ratio of piglets over the entire feeding period (P > 0.10)
whereas phytase improved feed conversion ratio (P <
0.05). During starter period, phytase linearly enhanced (P <
0.05) growth performance (258, 266, and 292 g/d) and feed
conversion ratio (1.55, 1.45, 1.45 kg dry matter/kg gain) but
no differences were detected during the weaner period (P
> 0.10). Phytase and P level interacted for apparent fecal P
digestibility (P < 0.05), so that phytase improved apparent
fecal P digestibility was more distinct in NC (48, 61, 68%)
than in PC diets (52, 62, 61%). The apparent fecal Ca
digestibility was higher in PC than in NC diets (68 vs. 58%),
and it was increased quadratically by phytase addition (61,
65, 63%). In conclusion, dietary phytase enhances piglet
performance during immediate post-weaning period, and
increased apparent fecal P and Ca digestibility.
Key words: piglet, phytase, phosphorus
1101 Phytase inclusion in pig diets improves zinc status
but its effect on copper availability is inconsistent.
P. Bikker* and A. W. Jongbloed, Wageningen UR Livestock
Research, Lelystad, The Netherlands.
We conducted 2 studies in young growing pigs (8–40 kg) to
estimate the effect of dietary phytase on their zinc (Zn) and
copper (Cu) requirements. In each of the studies one dietary
treatment was included with and without inclusion of 500
FTU of microbial phytase (Natuphos ® 5000G, BASF) per
kg to determine the effect of dietary phytase on availability
of the trace elements. Complexation of dietary phytate with
cations is a major cause of reduced bioavailability of Zn and
possibly Cu in pig diets. Inclusion of phytase is expected to
improve their availability and reduce the required dietary
inclusion. Each treatment comprised 10 pens with 8 pigs
each as experimental units. Diets were based on cereal
grains, SBM and RSM, contributing 30 mg Zn and 7 mg
Cu per kg to the basal diet. In experiment 1, 500 FTU/kg
phytase was added to a diet containing 15 mg Zn from zinc
sulfate and 160 mg/kg Cu from copper sulfate in addition
to Cu and Zn from feed ingredients. In experiment 2, 500
FTU phytase/kg was added to a diet containing 45 mg Zn
from zinc sulfate, without added copper sulfate. At the end
of an 8 week experimental period, feces were collected to
determine nutrient digestibility, blood was collected and pigs
were sacrificed to determine Cu and Zn in the liver. In both
experiments phytase inclusion increased zinc digestibility
(+10%, P < 0.001), serum zinc level (+0.4 mg/L, P < 0.001)
and liver Zn content (+129 mg/kg DM, P < 0.001). In exp.
1 phytase slightly increased copper digestibility (+6%, P
= 0.03) but reduced liver Cu content (−35 mg/kg DM, P =
0.04). In exp. 2 phytase reduced Cu digestibility (−16%, P <
0.001) without significant effect on liver Cu content. Results
suggest that the effect of phytase on copper availability
depend on the dietary copper and zinc content and the
response parameters studied. The consistent effects of
phytase on parameters of Zn status allow a reduction of
zinc inclusion in phytase-enriched diets. We suggest that
500 FTU of phytase may replace inclusion of 30 mg Zn per
kg of diet. The inconsistent effects of phytase on Cu status
require further attention.