Risk Factors Associated with Sow CullingRemoval

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Risk Factors Associated with Sow Culling/Removal

• Ken Stalder
• Extension Swine Specialist
• Iowa State University, Ames

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Female Culling Importance

• A sow remaining in the breeding herd for fewer
  parities is likely to produce fewer pigs in her
  lifetime, compared to a sow that remains in the
  breeding herd for a longer period of time.
• Reduces the opportunity for a sow to be
  sufficiently productive (pigs weaned and sold per
  lifetime) to achieve a return on the replacement
  gilt investment cost

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When does a sow pay for herself?
4
When does a sow pay for herself?
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Female Culling Importance

• Poor sow longevity requires larger replacement
  gilt pools, regardless of whether a pork
  production system raises or purchases these
  gilts.
• Costs of replacing a gilt
• Initial purchase
• Developing and acclimating
• Disease risk
• Poorer maternal production from younger sows

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Natural Life of Swine

• 12 15 years
• Most sows and boars are culled after their
  productive life is over

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Reported Averages

• Replacement Culling Avg. Parity
  Death
• Rate, Rate, At
  Culling Loss,
• PigCHAMP 60 42 3.8 7.8
• Pigtales 53 47 Not
  Reported

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How Do Top Herds Perform?

• 2002 PigCHAMP data Upper 10 Percentile
• Replacement rate 32.7
• Culling rate 22
• Death Loss 2.8
• Average parity at culling 5.5
• Koketsu et al. (1999)
• A cohort of females born in 1990
• Average lifetime pig production 67.2 pigs
• Average parity at removal was 5.6 parities

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What is possible?
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Reasons For Culling

• Reproductive failure 30 - 35
• Old age 15
  - 20
• Performance 15 - 20
• Feet and leg problems 10 - 15
• Death
  5 - 10
• Post-farrowing problems 3 - 5
• Other
  5 - 10

Reason
Percentage Culled
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Reason for Sow Removal Within the Reproductive
Failure Category

• Reason Percentage
  Culled
• Did not conceive 40 - 50
• Pregnancy check negative 15 - 20
• Fail to farrow 20 -
  30
• Aborted 5 - 15
• Other 0
  - 5

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Incidence of failure to breed, lameness and
culling for old age, in the sows according to
litter parity Dagorn Aumaitre, 1978
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Changes in growth and body composition of gilts
Baidoo, Samuel K., 2001 Allen D. Leman Swine
Conference (Adapted from Boyd, 1999)
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Risk Factors Associated with Poor Longevity

• Genetics
• Gilt Development
• Lactation Length
• Body Condition
• Repeat Breeding
• Seasonal Variation
• Sow Housing
• Feet and Leg Soundness
• Care Taker Skills and Management
• Behavioral Effects

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Genetics
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Heritability of Sow Longevity

• Tholen et al. 1996
• stayability from parity one to two, one to three,
  and one to four
• 0.05, 0.06 and 0.09
• Yazdi et al. 2000
• longevity ranging from 0.11 to 0.27.
• Serenius and Stalder 2004
• range of heritability from 0.05 to 0.19
• depending on the model used to analyze the data.

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Heritability of Sow Longevity

• Lopez-Serrano et al. 2000
• heritability estimates for stayabiltiy ranged
  from 0.07 to 0.11 in Landrace sows.
• Crump 2001-
• estimates ranging from 0.11 to 0.21,
• depending on whether survival analysis, linear
  model, or generalized linear model methods were
  used.
• Fortin and Cue 2002
• reported genetic parameters for length of
  productive life, defined as number of days from
  first service until culling.
• heritability estimates 0.16 and 0.13,
  respectively.

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Selection for Sow Longevity

• Generally not been a large focus directly at the
  nucleus level
• Trait is measured at the end of productive life
• Trait in direct conflict with making rapid
  genetic change
• Selection pressure, if any is placed, is directed
  at indicator traits affecting sow longevity
• Feet and leg soundness
• Backfat
• Other conformation traits

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Indirect Selection for Longevity

• Researchers have shown that genetics does
  influence traits thought to impact longevity.
• Age, weight, and backfat at puberty (Rydhamer et
  al, 1994 Bidanel et al., 1996)
• Leg conformation has been shown to be genetically
  correlated to length of productive life (Serenius
  and Stalder, 2004)
• Buck kneed fore legs were shown to be negatively
  associated with
• Age at first farrowing,
• Farrowing interval,
• Total number born, and
• Piglet mortality from birth to weaning
• Serenius et al. 2004.

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Crossbreeding Effects on Sow Longevity

• Crossbred females superior to their purebred or
  line parents
• Crossbred sows averaged 5.3 litters and purebred
  sows averaged 4.4 litters at culling (ivkovic et
  al., 1986)
• 55 of culling of purebred sows occurred before
  the 3rd parity
• 40 of culling of crossbred occurred during the
  same period

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Crossbreeding Effects on Sow Longevity

• Mean age and number of litters produced were
  lower in purebred Yorkshire sows when compared to
  crossbred sows (Jorgensen, 2000)
• Purebred sows had higher culling for locomotion
  and reproductive failure
• Crossbreds averaged 3.61 parities at culling
  while the purebreds averaged only 3.01 (Sehested
  and Schjerve, 1996)

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Breed or Line Makeup of Crossbred Females Impact
on Sow Longevity
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Breed or Line Makeup of Crossbred Females Impact
on Sow Longevity

• Similar percentages of culling by parity was
  reported in a study comparing purebred Large
  White and crossbred Large White x Landrace sows
  (Dagorn and Aumaitre, 1979)

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Line Choice CAN Impact Sow Longevity

• Longevity or productive lifetime differences
  approached 1 parity Rodriguez Zas et al., 2003
• National Pork Board Genetic Evaluation
• Comprehensive study of maternal performance
  including evaluation of sow longevity measures

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Production of 130 cohorts through six parities
from the National Pork Boards Maternal Line
Genetic Evaluation (Goodwin, 2002).
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Percent of 3283 entered females and (parity to
parity loss) that produced litters by line and
parity from the National Pork Boards Maternal
Line Genetic Evaluation (Goodwin, 2002).
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Gilt Development
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Sow Longevity and Backfat Relationship, Brisbane
and Chesnais, 1997

• Evaluated longevity in purebred Yorkshire and
  Landrace herds where backfat was measured on
  replacement gilts.
• Divided the gilts into 3 backfat categories.
• Leanest - lt 10 mm (.40 in.)
• Intermediate - 10 to 18 mm (.40 to .70 in.)
• Fattest - gt 18 mm (.70 in.)
• Strong negative association between leanness and
  longevity.

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Backfat and Sow Longevity cont

• Survival rate through the 4th parity of sows in
  the leanest category was poorer than those in the
  fattest category.
• 30 in Yorkshire
• 33 in Landrace

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Backfat and Sow Longevity cont
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Lactation Length
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Influence of Lactation Length on Farrowing rate,
Dial et al., 1995
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Body Condition at Weaning
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Condition Scores of Sows, Patience and Thacker,
1989

• Score Condition
  Body Shape
  
• 1 Emaciated
  Hip, backbone prominent to the eye
• 2 Thin
  Hips, backbone easily felt without
  
  
  applying palm
  pressure
• 3 Ideal
  Hips backbone felt only with firm palm
  pressure
• 4 Fat
  Hips, backbone cannot be felt
• 5 Over fat
  Hips, backbone heavily covered

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Effects of sow condition at weaning on
reproductive performance herd longevity
Measured in mature sows (parities 3-7) where
High top one-third and low bottom one-third
of total. Consisting of sows anoestrus,
failing to conceive, aborting or non-pregnant at
term. _______________________________ Gilt
management to maximize lifetime productivity
Feeding from selection to culling. Dr. Paul
Hughes, Pig Poultry Production Institute, Aug.
2001.
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Repeat Breeding
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Repeat Breeding

• As shown, the majority of culling occurs in
  commercial swine herds because of reproductive
  failure.
• An important aspect of reproductive failure is
  determining if initial reproductive performance
  has any lingering effect on reproductive
  performance in later parities.
• Studies indicate that 8.5 to 16.9 of females
  return to estrus after initially being mated
  after weaning.
• Sows should not be culled just because they do
  not conceive at their first estrus after weaning.
  
• Litter size from sows will not be adversely
  affected if they do not conceive until their
  second estrus
• Some indication of as much as a 0.5 pig increase
  in litter size when sows conceive at the second
  estrus after weaning.
• Repeat breeding problems can be the result of
  worker related issues, boar problems, and other
  causes that are not related to the sow.

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Seasonal Variation
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Seasonal Variation

• Many producers experience seasonal variation in
  reproductive performance
• Seasonal variation can lead to longevity issues
  or increased culling during certain times of the
  year.
• The variation in reproductive performance due to
  season may be the result of increased and
  fluctuating temperature, changes in light
  duration, or other factors
• Modern swine facilities, which house sows indoors
  and in individual stalls, can provide artificial
  lighting, and attempt to control temperature to
  alleviate some reproductive performance variation
  due to season
• Typical attributes of seasonal infertility
• 1) delayed onset of puberty
• 2) prolonged wean-to-estrus intervals
• 3) reduced farrowing rate, and
• 4) increased abortions

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Seasonal Variation

• Seasonal effects on farrowing rate tend to not be
  as large of a problem when sows are individually
  stalled
• Sows housed in pens tend larger problem with
  seasonal infertility
• Sow mortality during the summer months is higher
  than mortality in other seasons of the year
• Increased sow death is generally seen when
  temperatures rise to 75º F and higher
• increased risk of cardiac failure
• Sows farrowing in the summer have lighter litter
  weights at weaning and longer weaning-to-first
• Reduced appetite,
• Lower milk production, and body reserve
  mobilization in lactating sows.
• Do not overlook the effect that people or workers
  have on sow longevity
• Summer months are times when workers take
  vacations
• Substitutes or inexperienced personnel handle
  more tasks on a sow farm
• Explanation for a portion of the increase in
  problems associated summer time issues

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Sow Housing
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Sow Housing

• Sows in the U.S. are predominantly housed in
  gestation (62) and farrowing (84) stalls
• Ease of management,
• Reduced aggression, and
• Individual care and attention
• Difficult to determine the association between
  sow housing systems and longevity

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Sow Housing

• Feet and leg injuries can be problematic
• Cement flooring has been poorly cast,
• Improperly cleaned or managed, or
• Has extensive wear and

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Sow Housing

• Improved sow longevity does not appear to be
  necessarily associated with sows housed in
  individual stalls or grouped in pens during
  gestation
• Some small group housing systems have been shown
  to be quite successful.
• Sows housed in the Hurnik-Morris system (housed
  in small groups during gestation) had higher
  parity at culling and lifetime production when
  compared to sows in conventional gestation
  stalls.
• As size of our mature sow increases, there is an
  increased injury risk that may be related to
  individual gestation stall size
• Back injuries were related to gestation stall
  width, and the amount of time required for the
  sow to get up and lie down increases as sow size
  increases in relation to sow stall length.
• Sows in outdoor production systems have been
  shown to have higher mortality rates when
  compared to indoor production systems.

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Feet and Leg Soundness
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Indirect Selection for Longevity

• Still other reports evaluated leg conformation at
  six months of age (Jorgensen, 1996)
• Unfavorable effects on sows ability to produce
  through 3 parities
• Buck kneed front legs,
• Swaying hind quarters, and
• Upright pasterns on the rear legs
• Favorable effects on sows ability to produce
  through 3 parities
• Weak pasterns on front legs

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Gilt Selection Criteria - Soundness
Illustration of Leg Structural Deficiencies
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Gilt Selection Criteria - Soundness
Want to avoid problems like this.
Want more sows to look like this.
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Gilt Selection Criteria - Soundness
Illustration of Foot Structural Deficiencies
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Gilt Selection Criteria - Soundness

• Small inside toes are common
• Want even toes that are spread apart.

• Proper toe size will ease movement and improve
  stability
• Less likely to get foot problem
• Cracked toes
• Abrasions of foot pads

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Gilt Selection Criteria - Soundness
Other factors affecting soundness
Disease organisms causing arthritic conditions
Floor surface

• Rough floors
• Slats with sharp edges
• Smooth wet floors

• Streptococcus
• Mycoplasma
• Actinobacillus pleuropneumonia
• Etc.

Nutrition

• Calcium
• Phosphorus
• Zinc
• Biotin
• etc.

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Behavioral
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Behavioral Effects

• Few studies
• Housing conditions can create a continuous
  stressful situation for gestating sows.
• Stress impact on sow longevity ????
• Sows housed in groups whether outdoor or indoor
  system and have behavior issues
• fighting in lots,
• fighting in pens where sows cannot escape the
  aggressor sow,
• It is clear that all gestation sow housing
  systems for gilts and sows have benefits and
  challenges
• Not possible to identify which system will allow
  sows, to always have the longest productive herd
  life.
• Genetic Interaction??

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Caretaker Skills and Management
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Caretaker Skills and Management

• Management practices and the skills
• Observing for health changes
• Treating for illness, etc.
• Inexperienced labor force
• Very little training and little background with
  livestock
• Sow observation skills
• Off-farm employees
• More training
• Many of the skills necessary for maintaining
  successful pork operations just good husbandry
  knowledge
• Appropriate employee training programs are
  essential
• Herd size
• Studies have reported that sow mortality rate is
  significantly associated with average female
  inventory27, 51.
• Some intermediate herd size (400 to 600 sows) may
  be more ideal
• Related to the number of employees???
• Related to Operation Ownership???

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Culling Recommendations

• Do not cull if problem is management related
• Do not cull if problem is the boars fault
• Do not cull based on parity alone
• Do not cull if number of females to breed is low

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Culling Recommendation

• Cull unhealthy or lame sows
• Cull problem breeders (gilts and sows)
• Cull if diagnosed not pregnant more than once
• Cull if sow is a poor performer in the crate
  (number born alive, number weaned, weaning
  weight, etc.)
• Cull if sow has poor disposition

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Take Home Message

• Stress Gilt Development to Improve Longevity
• Soundness
• Structural and Reproductive
• Purchased Gilts
• Internal Multiplication Systems
• Early age at puberty
• Avoid selecting extremely lean gilts

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Thank You for Your Time and Attention

• Are there any questions?