Objective—To evaluate the success of removal and replacement decisions in commercial swine herds when sow removal was attributed to problems with fertility, fecundity, or old age.
Design—Retrospective case-control study.
Animals—3,000 sows removed from 3 commercial swine herds (case sows), 3,000 matched control sows retained in the herds, and 3,000 replacement gilts.
Procedures—Control sows were included to generate an estimate of reproductive performance that could have been expected had case sows been retained in the herds. Control sows and replacement gilts were followed up until the next farrowing or until removed from the herd, and reproductive performance, calculated as number of pigs born alive per mated female per year, was compared between groups.
Results—In 2 of the 3 herds, reproductive performance was significantly higher for replacement gilts than for control sows matched with case sows removed for reasons of fertility, and in all 3 herds, reproductive performance was significantly higher for replacement gilts than for control sows matched with case sows removed for reasons of fecundity. In the 2 herds with case sows removed because of age, reproductive performance did not differ significantly between replacement gilts and control sows. The odds of greater performance among replacement gilts relative to control sows ranged from 1.305 to 1.955 for removals attributed to fertility, 1.305 to 1.955 for removals attributed to fecundity, and 1.000 to 3.999 for removals attributed to age.
Conclusions and Clinical Relevance—Results suggested that performance-based removal and replacement programs in commercial swine herds may not yield the anticipated results.
Objective—To determine whether there is a relationship
between sow injuries and size of gestation stalls
relative to sow size.
Animals—267 pregnant sows.
Procedure—Sows were randomly selected from 4
swine farms. Sow and stall measurements were
obtained, and injuries were scored on the basis of location,
number, and depth. Ratios of stall length to sow
length and stall width to sow height were calculated.
Results—High injury scores were associated with
low ratios of stall length to sow length and stall width
to sow height.
Conclusions and Clinical Relevance—A small increase
in stall dimensions could reduce injuries and improve
well-being of sows considerably. (J Am Vet Med Assoc
Objective—To analyze the association of lameness and performance variables on sow longevity by use of time-to-event analysis.
Animals—674 sows from a commercial breeding herd.
Procedures—A lameness assessment was performed on each sow. Data on farrowing performance and longevity were collected for the sows during 3 or fewer parities from the database of the herd during 2005 and 2006. The association of risk factors with sow longevity within 350 days after lameness assessment was analyzed via Cox regression analysis. Pigs per day, total production days, and survival at 350 days after lameness evaluation were compared between lame and nonlame sows.
Results—Numbers of preweaning baby pig deaths, stillborn pigs, and mummified pigs were negatively associated with sow longevity within 350 days after lameness assessment. A higher number of pigs born alive and younger parity of sows were protective. Lame sows had a higher risk (1.710 times as high) of removal from the herd within 350 days after lameness assessment. The number of pigs born alive per day, survival of sows at 350 days, and total number of days in the herd were lower in lame sows.
Conclusions and Clinical Relevance—Results of this study indicated significant differences in the survivability of lame and nonlame sows in a commercial herd. Parity and farrowing performance variables were factors influencing sow longevity in this herd. Producers need to minimize sow lameness and remove lame sows from a herd early (when treatment is not an option) to minimize economic loss.
Objective—To characterize pattens of removal and
evaluate the associations among culling because of
lameness and sow productivity traits among culled
gilts and sows.
Sample Population—Data from a convenience sample
of 11 farms pertaining to the removal of 51,795
gilts and sows from January 1991 to December 2002.
Mean culling and mortality (death and euthanasia)
rates for all inventoried gilts and sows ranged from
23% to 50% and 4.7% to 9.5%, respectively.
Procedure—An analysis of categories of removal
(cull, death, or euthanasia) and reasons for removal of
gilts and sows was performed. Multivariate logistic
regression was used to determine associations
among culling because of lameness and sow productivity
traits among culled gilts and sows.
Results—Among sows that were removed, the proportion
of parity ≥ 1 sows that died (both death and
euthanasia) was > 3 times the proportion of parity ≥ 1
sows that were culled within 20 days after farrowing.
Among lame sows that were removed, the proportion
of parity ≥ 1 sows that died (death and euthanasia)
was higher than the proportion of parity ≥ 1 sows that
were culled within 20 days after farrowing. Among
sows that were removed, the proportion of sows that
died (deaths and euthanasia) was higher during lactation
than nonlactation. This was also observed among
lame sows that were removed.
Conclusions and Clinical Relevance—The proportion
of death among removed sows, especially lame
sows, was higher during lactation than nonlactation.
Results indicated that risk of death is not the same for
sows throughout their lifetime. (J Am Vet Med Assoc
Objective—To compare the location and severity of
injuries in pregnant sows housed in individual gestation
stalls with that in pregnant sows housed in
dynamic groups in pens with electronic sow feeders.
Animals—100 pregnant sows of parity 1 to 3 and various
Procedure—Fifty sows each were randomly allotted
to gestation stalls or group pens with electronic
sow feeders. Injuries were scored on the basis of
location, number, and depth of wounds. Injury
scores for sows in both housing systems were
compared during a period of 90 days. The influence
of factors such as duration of stay in the housing
system, parity, and body weight on sow injuries
was also examined.
Results—Injury scores were higher in group pens
with electronic sow feeders. As body weight
increased, injury scores decreased for sows housed
in group pens with electronic sow feeders and
increased for sows housed in gestation stalls. There
was a significant negative association between second
parity and total injury scores.
Conclusions and Clinical Relevance—Modifications
in housing system design and management procedures
are needed to reduce injuries in pregnant sows.
(J Am Vet Med Assoc 2003;223:1334–1338)
Objective—To compare well-being, performance,
and longevity of gestating sows housed in stalls or in
pens with an electronic sow feeder (ESF).
Animals—382 pregnant sows of parities 1 through 6.
Procedure—Sows were housed in separate stalls
(n = 176) or group pens (206) with an ESF. Well-being
of sows was assessed at various time points in terms
of injuries, salivary cortisol concentration, and behavior
in a novel arena or to a novel object. Farrowing performance
and longevity of sows were also assessed.
Results—Total injury scores (TIS) of sows in pens
were significantly higher at initial introduction and
mixing. In stall-housed sows, TIS was significantly
higher during late gestation. The TIS and cortisol concentration
were significantly lower in stall-housed
sows, compared with values for sows in pens. As parity
increased, the likelihood of higher median TIS
decreased significantly in pen-housed sows and
increased significantly in stall-housed sows. The TIS
of sows in pens was negatively correlated with body
weight and backfat thickness, whereas these correlations
were positive in stall-housed sows. Farrowing
performance and results for novel arena or objects did
not differ. Proportion of sows removed was significantly
higher for pens than for stalls; lameness was
the major reason for removal for both systems.
Conclusions and Clinical Relevance—Stalls impose
space restrictions for larger sows, resulting in injuries
during late gestation. Interventions are needed to
minimize aggression during initial introduction and
mixing and at the ESF in pens to reduce severe
injuries or lameness of gestating sows. (Am J Vet Res
Objective—To evaluate retention of porcine reproductive
and respiratory syndrome virus (PRRSV) in
houseflies for various time frames and temperatures.
Sample Population—Fifteen 2-week-old pigs,
two 10-week-old pigs, and laboratory-cultivated
Procedure—In an initial experiment, houseflies were
exposed to PRRSV; housed at 15°, 20°, 25°, and 30°C;
and tested at various time points. In a second experiment
to determine dynamics of virus retention,
houseflies were exposed to PRRSV and housed
under controlled field conditions for 48 hours.
Changes in the percentage of PRRSV-positive flies
and virus load per fly were assessed over time, and
detection of infective virus at 48 hours after exposure
was measured. Finally, in a third experiment, virus
loads were measured in houseflies allowed to feed on
blood, oropharyngeal washings, and nasal washings
obtained from experimentally infected pigs.
Results—In experiment 1, PRRSV retention in houseflies
was proportional to temperature. In the second
experiment, the percentage of PRRSV-positive houseflies
and virus load per fly decreased over time; however,
infective PRRSV was found in houseflies 48 hours
after exposure. In experiment 3, PRRSV was detected in
houseflies allowed to feed on all 3 porcine body fluids.
Conclusions and Clinical Relevance—For the conditions
of this study, houseflies did not support PRRSV
replication. Therefore, retention of PRRSV in houseflies
appears to be a function of initial virus load after ingestion
and environmental temperature. These factors
may impact the risk of insect-borne spread of PRRSV
among farms. (Am J Vet Res 2005;66:1517–1525)