Sow and Litter Performance for Two Genotypes in Crated and Group Gestation Systems
Monday, February 26, 2001By Iowa State University Researchers - This article looks at the effects of swine gestation housing on sow and litter performance of two genotypes as evaluated at the Iowa State University Lauren Christian Swine Research and Demonstration Farm near Atlantic, IA. The gestation housing systems were individual crates in a mechanically ventilated confinement building (CRATE) and, group-housed sows in a modified-open front building (MOF) or a bedded hoop structure (HOOP). All sows were fed individually.By M.S. Honeyman, associate professor, Department of Animal Science, and D. Kent, agricultural research specialist, ISU Lauren Christian Swine Research and Demonstration Farm, Atlantic, IA.
Summary and Implications
The sow and litter performance for two sow
genotypes housed in crated and group-housed gestation
systems was compared for two parities. The study was
conducted at the Iowa State University L. Christian Swine
Research and Demonstration Farm, Atlantic, IA. The
gestation housing systems were individual crates in a
mechanically ventilated confinement building (CRATE)
and, group-housed sows in a modified-open front building
(MOF) or a bedded hoop structure (HOOP). All sows
were fed individually. The group-housed sows were fed
with either feeding stalls (FS) or electronic feeders (EF).
The two sow genotypes were Yorkshire x Landrace
(WHITE sows) and Hampshire x Yorkshire x Landrace
(COLOR sows). The Yorkshire and Landrace breeding
was similar in both genotypes. Duroc terminal boars were
hand mated to all sows. The data analyzed were for litters
born from April through December 1998. The trial was
terminated because of a pseudorabies outbreak and
subsequent depopulation of the farm. Therefore, the
results of this study are only partial and should be
interpreted carefully. The WHITE sows demonstrated
superior litter traits compared with the COLOR sows. The
WHITE sows when housed in gestation crates, had larger
litters at birth and weaning than the COLOR sows and the
group-housed WHITE sows.
The dynamic groups, which
means sows were added and removed each week,
depressed the litter performance of the WHITE sows
compared with the WHITE sows housed in individual
gestation crates, but there was no similar effect for the
COLOR sows. The type of feeding system (FS or EF) did
not affect sow reproductive performance in the group
housing settings. The bedded hoop structures did not
differ from the modified open-front partially slatted floor
group housing for housing gestating sows, when sow and
litter performance was used as the comparison.
Methods
The gestation
housing systems were 1) individual gestation crates in a
mechanically ventilated, partially slatted floor, manure flush
confinement building (CRATE); 2) group pens in a naturally
ventilated, curtain-sided, partially slatted floor, modified-open
front building with no bedding and a deep manure pit (MOF);
and 3) group pens in deep-bedded, naturally ventilated hoop
structures (HOOP).
The group-housed gilts were individually
fed with either individual feed stalls (FS) or computerized
electronic feeders (EF). Sows fed with the electronic feeders
were given an initial training period the week after breeding
during which time they learned to use the feeders. The two
sow genotypes were Yorkshire x Landrace (WHITE sows) and
1/4 Hampshire x 1/2 Yorkshire x 1/4 Landrace (COLOR
sows). The Yorkshire and Landrace breeding was similar in
both genotypes. Duroc terminal boars were mated to all sows.
Farrowing occurred weekly throughout the year. Cross
fostering occurred across all sows.
Sows were naturally mated in a centralized, slatted floor
confinement breeding barn. Three to 7 days after breeding, the
sows were randomly assigned to one of the gestation systems.
The sows returned to the same assigned gestation housing
system after breeding for the second parity. The groups of
sows consisted of 40 to 60 sows. Sows were added weekly to
the groups from the breeding barn and sows were removed
weekly from the groups for transfer to the farrowing rooms.
Three to five sows were added or removed each week. Thus,
the group housed sows were in dynamic groups, i.e., the
composition of the group changed weekly. All breeding stock
tested PRRS negative.
The records analyzed were for farrowings that occurred
from April 1998 through December 1998. In early 1999,
pseudorabies virus (PRV) was diagnosed and the farm was
depopulated and later repopulated. The records of the herd
were not analyzed following the PRV diagnosis and for
approximately 30 days prior to the diagnosis. A total of 585
litters was included in the analysis. This included first parity
litters (n=409) and second parity litters (n=176). There were
322 litters from COLOR sows and 263 litters from WHITE
sows.
The gilts were purchased as market weight replacement
gilts and were generally cycling on arrival. After a 60-day
isolation period the gilts were eligible for breeding. Breeding
was delayed slightly to allow for construction at the farm to be
completed. Therefore, the gilts were bred no earlier than three
estrous cycles after puberty.
The sows were weighed and scanned for tenth rib backfat
prior to farrowing (approximately 110 days of gestation) and
at weaning. Sow lactation feed intake also was recorded.
During gestation all sows were fed 4.5 lb/day of a corn–soy
diet. During the last trimester the gestation feed allowance was
increased to 6 lb/day.
At farrowing the number of pigs born alive, stillborn pigs,
and mummified pigs was recorded. The birth weight of the
live pigs also was recorded. At weaning, the litter was
counted and weighed. Weaning occurred at 17–19 days of
age. Pig gain per day during lactation was calculated.
The sowed litter data were analyzed with SAS by
using General Linear Model. The model used sow
genotype (2), parity (2), and housing system (5) as the
variables. The sow/litter was the experimental unit.
Orthogonal contrasts were used for mean comparisons.
Least squares means are shown in the tables.
Results and Discussion
Note. Because of the short time period (April to
December), the variability of many of the parameters
measured and the few number of parities in this data set,
conclusions drawn from these data should be limited and
regarded as preliminary. In addition, the second parity
was cut short by the disease outbreak. After repopulation
a similar experiment will be initiated without the
challenges of new construction, multiple sow breed lines,
and management of a new farm.
A simple comparison of the two sow genotypes for
litter data and sow data is shown in Tables 1 and 2,
respectively. Parities (1 and 2) and housing system types
(five) were merged in the analysis. The WHITE sows had
more pigs born alive (7.5%), more stillborns, heavier pigs
at birth (9.5%), more pigs weaned (8.2%), and heavier
litter weaning weights (5.7%) at 18.5 days of age than the
COLOR sows (Table 1). If the number of live pigs and
stillborn pigs are combined, the WHITE sows gave birth
to more than an additional pig per litter than the COLOR
sows. Also, the pigs from WHITE sows grew slightly
faster (4.4%) from birth to weaning (Table 1). The
WHITE sows were heavier and had more backfat before
farrowing, and were heavier at weaning (Table 2). There
was no difference in backfat at weaning. The WHITE
sows consumed more feed per day during lactation.
Parity and genotype
An analysis of the two sow genotypes by both
parities for litter and sow data is shown in Tables 3 and 4.
As expected, sow performance in the second parity was
improved for both genotypes over the first parity for most
items measured.
Genotype and housing systems
The analysis of sow genotype by gestation housing
system is shown in Table 5 for the litter data and in Table
6 for the sow data. For the COLOR sows, there was no
difference in pigs born live per litter (NBA), stillborn
(SB), mummified pigs (MM), pig birth weight (BW), pig
gain (ADG), or weaning weight (WW) across housing
systems. The number of pigs weaned (NW) was greater
for the COLOR sows in crates than the COLOR sows
housed in groups with electronic feeder (MOF/EF or
HOOP/EF) (P<.05) (Table 5).
For the WHITE sows
housed in crates, the number of pigs born live per litter
(NBA) and number of pigs weaned (NW) was greater
than for the WHITE group housed sows (P<.05). The
number of stillborn pigs for the WHITE sows housed in a
modified open front with electronic feeder and hoop with
feeding stalls was greater than the other housing systems,
except for the modified open-front with electronic feeder
(P<.05). For the WHITE sows there were no differences for
mummified pigs, pig birth weight, weaning weight, or pig gain
(Table 5).
The COLOR sows housed in crates were heavier and had
more backfat prefarrowing than the COLOR sows in other
housing systems (P<.05) (Table 6). The COLOR crated sows
were also heavier (P<.05) and had numerically more backfat at
weaning (Table 6). The WHITE sows in hoops with electronic
feeders weighed less than the other sows (P<.05). There were
no other differences in WHITE sow weights or backfat by
housing type.
In examining the performance of all the sows (COLOR
and WHITE) for the five housing types, the WHITE sows
gestated in crates gave birth to more pigs and weaned more
pigs per litter than any other housing group (P<.05) (Table 5).
The number of stillborn pigs was highest for the WHITE sows
from modified open-front with an electronic feeder and from
the hoop with feeding stalls, although the later did not differ
from the modified open-front with feeding stalls. The WHITE
sows had numerically heavier pigs at birth and at weaning.
In general, the sows in crates were heavier at
prefarrowing and at weaning than the group-housed sows. The
WHITE sows had numerically more backfat than the COLOR
sows at both prefarrowing and at weaning. In aggregate there
is some evidence that the group housed sows, particularly
those fed with the electronic feeders, may have not received
adequate feed. This may be due to the stress of the dynamic
sow groups, the colder group housing systems or inexperience
in managing the electronic feeders.
Conclusions
Although this was a shortened trial due to the
depopulation, and the sows were young (first and second
parity), the results suggest that 1) the WHITE genotype sows
demonstrated superior litter traits than the COLOR sows; 2)
the dynamic groups and more rigorous environment of the
hoop and modified open-front facilities during gestation
reduced the litter performance of the WHITE sows; 3) the
group-housed sows in cold housing probably required
additional feed to match the weight of the crated sows; 4)
mixing the sows in dynamic groups likely reduced litter
performance; 5) the COLOR sows may be better able to adapt
to the group housing; 6) there was no apparent advantage in
litter performance using the electronic feeders compared to
feeding stalls; and 7) the bedded hoop structures were no
different than the modified open-front partially slatted floor
confinement as a group housing for gestating sows when using
litter and sow performance as the comparison.
Acknowledgments
We gratefully acknowledge the work of the farm staff at the
L.C. Swine Research and Demonstration Farm, A. D. Penner
for data analysis, the Wallace Foundation for Rural Research
and Development, The Iowa Pork Industry Center, and the
Leopold Center for Sustainable Agriculture.
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References
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