A prospective study on the influence of different Piétrain
terminal sire lines on production results in a Dutch pig
farm
T. van Sprang
ABSTRACT
In Dutch pig farming the sperm from terminal sire lines is purchased at breeding companies.
They provide numerous options when choosing a terminal sire line. This choice is complicated
by the lack of information on differences between the different terminal sire lines. The aim of
this study was to compare the four terminal sire lines, that are most frequently used in the
Netherlands: TP, P426, P408 and HM on the important production characteristics, TB, BA, PWM,
BW and SWW. The study was conducted on a Dutch sow farm counting 280 Topigs-20 sows.
Results were collected between January and June 2012. A total of 287 litters consisting of 4012
piglets were analyzed. The results for both BW and SWW showed significant differences
between sire lines. It seems that terminal sire line has a greater influence on weaning weight,
than birth weight.
INTRODUCTION
In Dutch pig farming the sperm from
terminal sire lines is purchased at breeding
companies. The terminal sire lines are
crossbred products with each unique
genetic capacities, that are capable of
inheriting good fattening qualities to their
offspring. The technical results and
slaughter qualities of this offspring, are
partly defined by the chosen terminal sire
line(1).
The Dutch pig husbandry provides
numerous options when choosing a
terminal sire line. Breeding companies focus
their breeding program on different
inheritable characteristics, and a farmer
needs
to
choose
between
these
characteristics taking in consideration his
own production goals, e.g. maximum
numbers of piglets, and specific desires of
his customers, e.g. growth potential or
carcass quality. As some characteristics
demonstrate a negative correlation, for
example between growth potential and born
alive piglets(2), a sire line with merely
positive characteristics does not exist.
1
The pig farmer has to choose between these
wishes. This choice is complicated by the
lack of information on differences between
the different terminal sire lines.
Because of an increasing demand for pigs
with high lean muscle percentages, the
Piétrain terminal sire lines(3), have become
frequently used. The user percentages of
different terminal sire lines in the
Netherlands are only partly known. Two
important breeding companies, Topigs and
PIC, state that in 2012 the following Piétrain
terminal sires were mostly used: from
Topigs, Top Pie (TP), from PIC, PIC408
(P408) and PIC426 (P426) and from Hypor,
Maxter (HM).
The most important indicators on sow
farms regarding production qualities, are:
total number of piglets born in a litter (total
born, TB), number of piglets born alive
(born alive, BA) and the pre-weaning
mortality (PWM). The birth weight (BW)
and weaning weight (WW) are also
important because they influence the
growth qualities of the finisher pig(4, 5).
Because not all litters have the same
lactation length, the weaning weight is
difficult to compare between different
litters. Calculation of the average daily
weight gain (ADG) is a way of joining the
two parameters BW and WW, together and
eliminating the effect of no. of lactation
days. ADG however doesn’t take into
account that low BW piglets even with a
high ADG, possibly have low weaning
weights. Therefore, in this trial, a
standardized weaning weight (SWW) is
used. The SWW is calculated by multiplying
the ADG by a standard lactation period of 23
days, and adding the birth weight.
After weaning the sows are selected for the
next round. Al sows are inseminated within
one week from each other and sperm is
ordered at a local semen supplier and stored
on the farm for a maximum of three days
before use. Within one group the sows are
randomly inseminated with sperm from one
of the four terminal sire lines. In every
group 2-3 different terminal sire lines were
used. For each sow was registered with
which of the end sire lines she was
inseminated. To prevent any conflict of
interest the boars were anonymised. From
this stage on, the boars were numbered B1B4.
Although it is well documented that the
piglets’ characteristics are partly influenced
by the chosen terminal sire line(1, 6, 7), no
field data are available on differences in
influence of the four, in the Netherlands,
most used, Piétrain, terminal sire lines, on
piglet characteristics.
During gestation the sows are housed in
group housing with free access crates. The
groups are kept together the entire
gestation period and are never mixed with
other groups. Al sows in the trial were fed
according to the same feeding regime.
The aim of this prospective study is to
obtain such data by comparing the four
terminal sire lines, that are most frequently
used in the Netherlands: TP, P426, P408 and
HM on the important production
characteristics, TB, BA, PWM, BW and SWW.
The results will support Dutch pig farmers
in making an evidence based choice for a
specific sire line.
MATERIAL AND METHODS
The study was conducted on a Dutch sow
farm counting 280 Topigs-20 sows. The
Topigs-20 sow is a crossbreed between a Zline and a N-line. The z-line sows are bred
from Yorkshire genetics, and the N-line
sows are bred from Dutch landrace genetics.
The farm works with a so-called 4-week
rotational system. In this system every 4
weeks a new group of sows is inseminated.
These groups exist of approximately 55
sows. In this study seven groups are used to
assess the different terminal sire line result.
2
One week before parturition the sows are
moved to the farrowing units. They are
placed randomly in the pens. On the farm
there are two types of farrowing pens. In the
one type the sows are housed on a raised
slated floor, the creep area is located at the
front of the sow and has a concrete floor.
The creep area is heated with a heating
lamp. In this type of farrowing unit there is
room for six sows. The other type of
farrowing pen has a half concrete, half
slatted floor. The creep area is located
oblique next to the sow, and is heated with a
heating lamp. In this type of farrowing unit
there is room for ten sows. There are five
type 1, and five type 2 units.
At day of birth al viable piglets were
weighed and individually tagged with an
individual identification number (ID). The
weighing took place in the farrowing unit.
The equipment was cleaned and disinfected
between every litter to minimize indirect
contact between litters. In addition to the
BW, parent ID’s were also recorded. Data on
TB and BA were recorded per sow and later
matched with the data of individual piglets
based on their mothers ID.
On the day before weaning al piglets were
individually weighed again. The weaning
weights were linked to the individual piglet
ID. PWM mortality was recorded for every
sow and by mother ID linked to the
individual piglets.
The results were analyzed using a mixed
linear model(8). This model enabled
correcting for the effect of any covariate’s.
Figure 1 gives an overview of the possible
covariate’s(9-13).
Not
all
possible
covariate’s were recorded in the trial.
Recorded effects are listed in the recorded
effect boxes. Most of the co-variants have an
effect on the results in this trial by
influencing the sow. To test the correlation
between these factors and the sow, the
different factors were tested using a
bivariate correlation test. The factors that
were assumed identical during the trial are
presented in the boxes equal effects. Data on
these factors were not recorded in this trial.
To identify the effect of the recorded
possible co-variations, their effect was
tested using a linear regression test.
There is also interaction between the
characteristics in this trial. For example
between TB an BW(14, 15). Because the aim
of this study was to compare the effect of
different boars on each individual, tested
characteristics, it was decided not to correct
the results for interference between
different test characteristics.
For
analyzing
the
production
characteristics, TB, BA and PWM, the litter
of each individual sow was used as an
experimental unit. In the analyses of BW
and SWW the individual piglets were used
as experimental unit.
3
Figure 1. Possible co-variants influencing test characteristics.
Dotted lines represent sow influences.
RESULTS
In this study a total of 287 litters was born,
61 from a TP boar, 65 from P426, 84 from
P408 and 77 from HM. Because only viable
piglets were included in the trial, not all
piglets born alive were included. From the
4012 piglets born alive, 3793 piglets were
weighed at birth and 2843 piglets were also
weighed at weaning. The difference in
number of records for BW and WW is partly
caused by the PWM of 2.39/litter This only
accounts for 686 of the 950 missing entries.
The other 264 missing entries were caused
by unforeseen data-loss, due to software
failure.
The correlation between sow influencing cofactors was determined. There was a large
correlation between sow and parity, 0,97.
Because this concludes that the parity is
responsible for the majority of the soweffect, it was decided to correct, if necessary,
for parity instead of, for sow.
B1 (14,52 sd 2.36), and B2 (14,32 sd 2,76)
boars. The other 2 boars achieve lower
results, B3 (13,9 sd 3,43) and B4 (13,34 sd
3,83).
The results are presented in table 1. The
linear regressions showed that season
significantly influenced the results of BW
and that parity, and season, significantly
influenced SWW. Therefore also the
corrected results for BW and SWW are
presented.
PRE-WEANING MORTALITY
The PWM is highest in litters from B1 (2,77
sd 2,53). Litters from B3 (2,37 sd 2,25) and
B2 (2,32 sd 2,07) achieve lower PWM’s . The
lowest PWM is achieved with B4 (2,16 sd
2,44).
The results for TB, BA and PWM are
presented in figure 2. There was no
significant difference in TB, BA and PWM
between sire lines found in this trial
(P>0,05). The un–corrected results for BW
and SWW are presented in figure 3. The
results for both BW and SWW showed
significant differences between sire lines.
BIRTH WEIGHT
In the uncorrected results, there is no
significant difference between the two boars
achieving the highest BW, B4 (1.44 sd 0,37)
and B3 (1,41 sd 0,42). The other two boars
achieve significantly lower BW’s, B2 (1,34
sd 0,33) and B1 (1,32 sd 0,34).
The results which are corrected for season,
show that, the highest BW is achieved in
litters from B1 (1,17). The other boars, B2
(1.15), B3 (1.12) and B4 (1.12), achieve
lower results. The differences between
these corrected results are not significant.
TOTAL BORN
The highest mean TB is achieved with B2
(15,7 sd 3,06). B2 (15,46 sd 2,88) and B3
(15,38 sd 3,68) score almost equal for TB.
The lowest number TB is achieved with the
B4 (14,49 sd 3,85).
SWW
BORN ALIVE
In the uncorrected results, the Highest SWW
is achieved with B4 (6,90 sd 1,34). The
The highest scores for BA are achieved with
Boar
B1
B2
Parity
B3
B4
F
Sig.
F
Sig.
# Litters
61
65
84
77
-
-
-
-
# BW piglets
839
869
1107
978
-
-
-
-
# SWW piglets
657
730
759
697
-
-
-
-
TB
Mean
15,46a +/-2.88
15,77a +/- 3.06
15,38a +/-3.68
14,49a +/- 3.85
0.14
0.71
4.98
0.26
BA
Mean
14,52a +/- 2.36
14,32a +/-2.76
13,90a +/- 3.43
13,34a +/- 3.83
0.07
0.79
4.77
0.30
PWM
Mean
2,77a
+/- 2.53
2,32a
+/- 2.07
2,37a
+/- 2.25
2,16a
+/- 2.44
0.00
0.97
1.69
0.20
BW
(kg)
Mean
1,32a
+/- 0.34
1,34a
+/- 0.33
1,41b
+/- 0.42
1,44b
+/- 0.37
SWW
(kg)
Mean
Corr
Corr.
1.17a
6,39a
+/- 1.50
6.30a
1.15a
6,56a
+/- 1.47
6.38a
1.12a
6,54a
+/- 1.50
6.42a
0.46
0.82
117.7
0.00
1.12a
-
-
-
-
6,90 +/- 1.34
17.56
0.00
17.12
0.00
6.75
-
-
-
-
Table 1. Numbers and results.
ab means within rows with the same superscript are not significantly different
4
Season
other boars achieve significantly less SWW.
The highest of the rest is B2 (6,56 sd 1,47),
B3 (6,54 sd 1,50) achieves almost the same
results. B1 (6,39 sd 1,5) achieves the lowest
SWW.
has the significantly highest SWW. The
other boars achieve lower SWW, B3 (6,42),
B2 (6,38) and B1 (6,30).
When the results are corrected for season,
and parity, the means for SWW are lower,
but the significance in differences, between
the four boars, remains the same. B4 (6,75)
Fig. 2. Means of TB and BA and PWM, achieved with Topigs-20 sows using four
different terminal sire lines.
Fig. 3. Means of BW and SWW achieved with Topigs-20 sows using four different
terminal sire lines.
5
DISCUSSION
MATERIALS & METHODS
This trial was executed in the field. Because
the trial couldn’t interfere too much with the
normal operations on the farm some of the
circumstances were not optimal for reliable
results. Wherever possible extra measures
were taken to minimize the influences but
there are some factors left that could have
influenced the results.
Season.
In this trial the first inseminations took place
in the end of autumn, and the last in the end
of the spring. Seasonal influences on
reproductive
performance
are
well
described(16, 17). Possible effects are lower
farrowing rates or reduced litter size. There
are also seasonal effects described on
subsequent performance of the piglets(18,
19).
The seasonal influences in this trial could
have been excluded by conducting the trial in
one season. This however, would have
limited the number of litters in the trial.
Another option would have been to use
every terminal sire line in every
insemination group. In this trial it was
decided not to do that because of practical
reasons regarding ordering and storage of
the sperm and administration.
By not using every terminal sire line in every
group it became questionable whether to
correct the analyses for insemination group,
i.e. season. It was not possible to conclude
whether apparent seasonal differences were
indeed caused by difference in season or
rather by the influence of different boars.
Seasonal influences are caused by the effect
of changes in day length on the sow, and a
negative effect of heat stress in summer on
both piglets and sows(10, 19). The results of
this trial were collected in the winter and
spring. Therefore it is plausible to assume
6
that the season had no significant effect on
the results in this trial, and no correction for
seasonal influences has to be made. Another
fact supporting the assumption that there
was no significant seasonal effect in this trial
is, that the piglets most likely to experience
heat stress and therefore lower WW, were
the ones in the latest insemination groups.
These piglets achieved in this trial
significantly higher SWW than the other
piglets.
Choice of terminal sire lines
In this trial, the sperm of the used sire lines
was ordered via normal supply chains.
Because only the sire line was registered and
not, the individual boar, it is theoretically
possible that one unique boar was used more
frequent and could thereby have a
disproportional influence on the results.
However the chance of one boar being used
multiple times is less than 1.1E-. It was
decided to neglect this possibility in the trial.
Stratifying groups
The choice of terminal sire line was
randomly selected for each sow. It is possible
that factors that could influence reproductive
performance, for example parity(20, 21) or
previous litter size and lactation length(22)
were not equally distributed over the seven
groups. It was not possible to stratify the
groups. By using a linear regression model, it
was possible to excluded a sow dependent
influence on the results.
Cross-fostering
To maximize piglet survival, it is common
practice to cross-foster some piglets from a
sow with a large litter, to a sow with a
relatively small litter. The cross-fostering of
piglets can have negative effects on growth
and development of mixed litters (21, 2325). And positive effects on survival of
piglets in large litters. On this farm it was not
possible
to
prohibit
cross-fostering
completely. Instead, a modified cross-
fostering system was used to minimize the
negative effects. Piglets were maximally once
transferred to another sow and not more
than two litters were mixed at one sow.
Despite this adapted cross-fostering strategy
it is possible that the cross fostering
interfered with the results. The goal of cross
fostering is to maximize survival in piglets.
This results in better circumstances for small
piglets. In this trial it could be assumed that
the cross fostering improved the result of
low BW piglets, and thereby decreased the
significant differences in results. If there
would have been no cross fostering the
results would probably have shown greater
significant differences.
Housing
Most of the housing for sows was identical.
Only in the farrowing stable there were two
different types of farrowing units. Because
sows were randomly placed in the farrowing
pens it is possible that the different type of
farrowing pens were not equally distributed
in the different groups. It is possible that
differences in housing system influenced the
production results. But most research shows
that this possible influence, if there is an
influence at all, is small(26-28).
Correlated characteristics
The characteristics that were tested in this
trial are mostly correlated(13, 29-33). One
characteristic cannot by analyzed without
looking at the other characteristics.
Nevertheless it was chosen not to correct for
these correlated factors in the analyses. The
aim of the study was to compare four
different Piétrain terminal sire lines on some
important production characteristics. By not
correcting the results for mutual correlation
a better representation of the individual
characteristics is given. Of course in
comparing the results and deciding what
terminal sire line to use, all the different
characteristics must be taken into account.
7
RESULTS
The results show no significant results for
TB, BA and PWM. Al these characteristics
have a relatively large sd. Therefore it is less
likely to achieve significant differences with
relative small number of records. The results
indicate that a higher TB doesn’t necessarily
results in more BA. This is in contrast with
most other research(34, 35), which reports
an increased percentage of stillbirth but not
an increased number. This results calls for
more research to discover if there is a
difference in the influence of different
terminal sire lines on perinatal survival.
The results show a significant difference in
BW. These differences cannot be explained
by a difference in TB, because these results
show no significant difference on that
characteristic and the lowest birth weight
piglets are not the lowest TB piglets. This
result is in contrast with most research (15,
36, 37) which states that a larger TB results
in lower BW, and indicates that the terminal
sire line has a larger influence on BW than
the TB.
In this study the results for WW were
recalculated into SWW. The authors think
that this is a good method to correct for
different weaning ages and take both the
ADG as the BW into account. But SWW is not
a flawless characteristic. A factor that is not
taken in to account, is the fact that the
growth rate of a piglet increases as it gets
older. Therefor piglets weaned at a later age
automatically achieve a higher ADG.
Correcting for this higher daily gain is
difficult because data on piglets growth
curves is not present. The goal in this study
was to compare the different terminal sire
lines, and this was achieved by using the
SWW.
The SWW shows significant results between
different terminal sire lines. B4 achieves
both highest BW and highest SWW. The fact
that piglets from B3 have a higher mean BW
than the litters form B2 and B1, but not a
higher SWW supports the assumption of an
influence of terminal sire line on BW and
SWW.
CONCLUSION
In this trial there are significant differences
between the four tested Piétrain terminal
sire lines on the characteristics BW and
SWW. By not using every terminal sire in
every birth group the results couldn’t be
corrected for season and therefor a seasonal
influence cannot be excluded. There is need
for further research into this subject to prove
that the indications to the influence of
terminal sires on these production
characteristics can be repeated.
ACKNOWLEDGEMENTS
Conducting a trial of this size is an enormous
task. I could have never done it on my own. I
would like to thank PIC for making this trial
possible. Without my colleague M.F. Hekman
and the help of many students of the
University of Utrecht the amount of
fieldwork in this trial could not have been
carried out. In analyzing the data and writing
this report I got essential help from my
teachers, Dr. S.J. van Beurden, Drs. E.A.W.S.
Weerts, Drs. M. Derks and most important, B.
Swildens.
8
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