34 E
.M.A.M. Bruininx et al. Livestock Production Science 67 2000 31 –39
effect within animals between sampling days. The humoral immune response. Averaged over the total
experimental period Hb concentration of FE pigs was effects of the additional iron injection, immunization
higher P ,0.05, Table 2 than that of SALINE pigs procedure, immunization moment, genotype and
21
6.8 vs. 6.7 mmol l . Averaged over the ex-
their interactions were tested against error term 1. perimental period, Hb concentration was not affected
The effect of sampling day and all interaction effects by immunization procedure, immunization moment
with sampling day were tested against error term 2. and genotype Table 2. Although blood Hb level of
FE pigs was higher P ,0.01; Fig. 1 at day 6 after weaning, there was no interaction P .0.1 between
3. Results
an additional iron injection and time sampling moment. Both immunization procedure and im-
Preliminary analysis of the various antibody titres munization moment did also not interact with time
with model 1 showed the presence of several three P .0.1; Fig. 1. The pattern kinetics of the blood
way interaction effects between immunization pro- Hb concentration was different among the three
cedure, sampling day and the other effects. Further- major genotypes as indicated by the interaction effect
more, preliminary analysis within the PLAC treat- between genotype and time P ,0.05; Fig. 1 con-
ment showed that there were nearly no effects of an centration.
additional iron injection, immunization moment and genotype. Therefore, the effects of an additional iron
3.2. Growth injection, immunization moment and genotype were
tested only in immunized animals using a similar Averaged over the total experiment, ADG was not
model as 1 omitting the effect of immunization. affected P .0.1 by an additional iron injection,
In general, immunized pigs mounted similar sys- immunization procedure and immunization moment
temic antibody responses directed to KLH and OA. Table 2. With regard to genotype, the highest ADG
Therefore only the results of the KLH challenge will was found in the predominantly Finnish Landrace
be presented. The antibody response to TT will not
21
pigs 359 g day ; Table 2. Averaged over all
be shown because it was masked by TT resembling treatments, ADG increased over time P ,0.001
antigens at the time of analysis cross-reactivity.
21 21
from 131 g day in week 1 to 471 g day
in week 3.1. Blood hemoglobin concentration
5. This increase in ADG with time was not affected P .0.1 by an additional iron injection, immuniza-
The primary aim of this study was to assess the tion procedure or immunization moment. Growth
effect of an additional iron injection for weanling pattern was affected P ,0.001 by genotype. During
pigs on day 21 on their Hb status, growth and the fifth week after weaning, pigs that had pre-
Table 2 Least squares means for the effects of an additional iron injection, major genotype and immunization moment on average daily gain ADG,
average blood hemoglobin concentration Hb, average Keyhole limpet hemocyanin KLH specific antibody titer total Ig, IgM, and IgG of immunized newly weaned pigs during the experimental period
Item Iron injection
Major genotype Immunization moment
a a
a
Iron Saline
S.E.M. GY-z
FL DL
S.E.M. D1
D21 S.E.M.
Number of pigs 60
60 –
49 45
26 –
61 59
–
21 b
ADG g d 343
329 10.5
339 359
309 12.9
334 337
10.5
21 c
Hb mmol l 6.8
6.7 0.06
6.7 6.8
6.8 0.07
6.8 6.8
0.06
b
IgTotal 6.7
6.6 0.18
7.1 6.2
6.7 0.21
6.7 6.7
0.18 IgM
4.6 4.6
0.19 4.8
4.5 4.5
0.23 4.7
4.5 0.19
b
IgG 3.8
3.8 0.19
4.1 3.3
4.0 0.23
3.6 4.0
0.19
a
S.E.M., pooled standard error of the mean.
b
Major genotype main effect, P ,0.05.
c
Additional iron injection main effect, P ,0.05.
E .M.A.M. Bruininx et al. Livestock Production Science 67 2000 31 –39
35
Fig. 1. Least-square means of blood hemoglobin Hb concentration in newly weaned pigs during the experimental period. Panel A: the main effect of iron treatment pigs injected with additional iron [FE] vs. placebo pigs [SALINE]; panel B: the main effect of immunization
procedure immunized pigs [IMMU] vs. placebo pigs [PLAC]; panel C: main effect of immunization moment pigs immunized 1 day before [D21] or 1 day after [D1] weaning; and panel D: the main effect of major genotype predominantly Finnish Landrace pigs [FL] vs.
predominantly Dutch Landrace pigs [DL] vs. predominantly Great Yorkshire pigs [GY-z].
dominantly the FL genotype achieved the highest moment Table 2. Immunized pigs that had pre-
21
ADG 550 g day , whereas, pigs that had pre-
dominantly the GY-z genotype had a higher total Ig dominantly the DL genotype achieved the lowest
and IgG response to KLH than pigs that had
21 21
ADG 378 g day . The ADG 485 g day
of predominantly the FL or DL genotype P ,0.05;
pigs that had predominantly the GY-z genotype was Table 2. Genotype had no effect on the IgM
intermediate Fig. 2. response to KLH.
Total antibody titers and titers of the IgM and IgG 3.3. Keyhole limpet hemocyanin
isotypes were affected by time P ,0.001. The patterns of the total Ig, IgM and IgG titers against
Averaged over the total experiment, total Ig, IgM KLH were not affected P .0.1 by additional iron
and IgG titers against KLH were not affected P . administration. Immunization moment did affect
0.1 by an additional iron injection or immunization P ,0.05 the pattern of total Ig, IgM and IgG
36 E
.M.A.M. Bruininx et al. Livestock Production Science 67 2000 31 –39
Fig. 2. Least-square means of ADG of newly weaned pigs during the experimental period. The main effect of major genotype
predominantly Finnish Landrace pigs [FL] vs. predominantly Dutch Landrace pigs [DL] vs. predominantly Great Yorkshire pigs
[GY-z].
responses Figs. 3A, 4A and 5A. At day 7 the total Ig titer to KLH of pigs immunized 1 day before
weaning D21 was higher than of pigs immunized 1 day after weaning D1. The pattern of total Ig
response to KLH was also affected P ,0.005 by genotype Fig. 3B. At day 11, the total Ig titer for
2
GY-z pigs was approximately 1.4 units log-scale higher than that of FL pigs. This difference was
reduced to approximately 1.1 units from day 14
Fig. 3. Least-square means of Keyhole limpet hemocyanin
onwards. The development of the total Ig titer
KLH-specific total antibody titer of immunized newly weaned
against KLH of DL pigs was intermediate to GY-z
pigs during the experimental period. Panel A: the main effect of
and FL pigs. In contrast, the kinetics of IgM and IgG
immunization moment pigs immunized 1 day before [D21] or 1 day after [D1] weaning; and panel B: the main effect of major
responses to KLH were not affected by genotype
genotype predominantly Finnish Landrace pigs [FL] vs. pre-
P .0.1; Figs. 4B and 5B.
dominantly Dutch Landrace pigs [DL] vs. predominantly Great Yorkshire pigs [GY-z].
4. Discussion
