Analysis and interpretation of reproductive performance

 

The success or failure of reproduction should be measured in output from the finishing floor.  Even when the farm sells weaners, the only real income arises when these pigs are sold for meat or replacement gilts.

 

The traditional analysis systems concentrated on the adult herd’s productivity and largely ignored their impacts on the growing/finishing herd.  This lead to a concentration on non-productive sow days and pigs per sow per year.  However, neither of these numbers actually relate to profit nor do they allow for analysis of the whole farm budget.    Non-productive sow days and pigs per sow per year are also easily open to manipulation to enhance the stockpeople’s results. For example, changing the definition of the “gilt” or manipulating cull sow management can have a major impact on the adult herd parameters, but these numbers have no impact on the growing/finishing herd.  These traditional analysis systems still have a role – once the target kg meat paid for per batch has been met, to help reduce the cost of production.

 

The move towards linking the reproductive success of the adult herd and the grow/finishing herd has been driven by the need to accommodate the welfare requirements of the finishing pig.  Many countries around the world have legislated stocking densities (EU) or more typically, industry suggested guidelines – USA, Canada and Australia.

 

Stocking density guidelines should be embraced by the veterinary community as they can be extremely useful in an analysis of a farm’s reproductive performance. Neither the farm nor the veterinarian should ignore the recommendations of governments or the farming bodies.

 

Setting reproductive targets and interference levels

 

Batch farming

If we generally accept all-in/all-out management of pigs, this leads to the batch concept.   In batch farming, pigs are produced in a batch and they stay together from conception to slaughter.  If this concept is accepted then batch targets and interference levels can be set.

A batch is an agreed fixed time parameter which in commercial pig production varies from a day to 4 weeks depending on the filling the grow/finishing herd all-in/all-out.

 

Determination of the batch breeding target

 ((Size of the unobstructed finishing floor m2 ) ÷ (space required per finishing pig)) ÷ finishing rate %1 =

Minimum number of pigs weaned per batch

(1. The finishing rate % is the animals remaining after the post-weaning mortality and breeding gilts is removed from the finishing batch – target 95%)

 

The minimum number of pigs weaned per batch ÷ pigs weaned per batch farrowing place = Minimum number of sows2 to farrow per batch = number of batch farrowing places

(2. A sow is defined as any female pig post-mating)

 

            Number of batch farrowing places ÷ batch farrowing rate %3 =

Minimum number of females to breed = The batch breeding target

 

This might be best illustrated with an example.

Example: A farm within the European Union:

 

Pigs sold at 110 kg live-weight

741 m2 of unobstructed finishing floor is available per batch of pigs

0.65 m2 is the minimum recommended space required per finishing pig (ref)

95% finishing rate is currently enjoyed by the farm

12 pigs are weaned per batch farrowing place

85% farrowing rate has been the average farrowing rate % recorded over the last 6 months

 

Mathematics =  ((((741÷0.65) ÷0.95) ÷12) ÷0.85) = 118 females to bred per batch

Note the mathematics must work in whole number of animals.

 

Use the following spreadsheet to calculate your own breeding target:

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It this logic is followed it removes a major source of variation on farms – the chronic over- and under- stocking of finishing buildings.  This stocking density stress is at the core of many cases of vice, respiratory and digestive disorders of growing pigs.

 

Analysis of reproductive performance

In the batch, the adult herd’s impact on the farm’s productivity and cost controls is to the point where the required number and weight of weaned pigs is produced.  The analysis and interpretation of the adult herd should be targeted towards the production of weaned pigs.  The genetics and management of the weaned pig will then determine its income potential, post-weaning.

 

Major parameters defining reproductive output

Setting batch breeding targets

 

First day of the batch

To ensure that the same “group/batch” of sows and gilts being bred are the same group of sows to be farrowed the farm records must start the day after weaning.  The normal minimal gestation length is 112 days.   Therefore, if a female is bred, the earliest normal farrowing could be 112 (exactly 16 weeks) later.  If the farm weans on a Monday, the first day an empty farrowing place will be available with be the next day – a Tuesday.   Any sow which farrows in this place has to be considered part of the weaned batch.  This only occurs if the breeding records start the day after weaning. These ‘aberrant’ sows are normally gilts and returns as the weaned group are going to return to estrus 4-6 days post-weaning.

Determining the number of batch farrowing places available

Achieving all-in/all-out must start in the farrowing area.  The weaning age and batch length (time in weeks) determine the number of batch farrowing places available.

For example a one week batch weaning pigs at 4 weeks of age requires 5 farrowing spaces.

 

Number of rooms required per batch type to allow for all-in/all-out

 

Batch time

0.5w

1w

10d

2w

3w

4w

Weaning age

 

 

 

 

 

 

3 weeks

8

4

 

2

 

1

4 weeks

10

5

3

 

2

 

5 weeks

 

6

 

3

 

 

 

What options are available for your output   spreadsheet

 

Ensuring each batch farrowing place is filled with a farrowing sow

Traditional approach

Traditionally a breeding target has been set from the farm’s historical farrowing rate %3

3. Farrowing rate % = 100 * (total number of females farrowed) ÷ (total number of females bred) in a specified period of time.

However, this number is a mean number and cannot be easily applied to a batch.

 

Batch farrowing rates over the year

An example of the range of farrowing rates over the year – an Australian outdoor unit

The average farrowing rate is 73%.  But adopting this farrowing rate would result in empty farrowing places in many batches of pigs.

Note indoor farms will generally produce a graph with less variation over the year and between batches.

 

Determine the break-even economic farrowing rate percentile where it is cost effective to ‘over-breed’.  On many farms taking a lower 10 percentile proves to be  cost effective.  If this is used, it would naturally result in the batch farrowing places being all filled 90% of the time.  Thus for a weekly batch farm this results in 50 batches out of 52 filled. If the traditional average farrowing rate % is taken as the target, this would result in complete filling of the batch farrowing places 26 out of 52 batches.

 

Additional complications:

Impact of Seasonal variation in farrowing rates

The farrowing rate varies over the year because of natural seasonal fertility.

This is predictable and if the farm demonstrates a seasonal fertility pattern, this needs to be accommodated within the batch breeding target where appropriate.

 

The farrowing rate by month bred for the Northern Hemisphere (North American Data) and the Southern Hemisphere (Western Australian Data) combined data 2002-2004

Not all animals in the breeding pool have the same farrowing rate

The breeding pool of females is composed of three groups:

The weaned sow

The return sow

The gilt

 

Each of these different groups has different predictable farrowing rates and this need to be taken into account when determining the batch farrowing rate.

 

The weaned sow

 

Major factors affecting the farrowing rate in the weaned sow

Lactation length

Parity of the sow.   Gilts are considered separately.

The Wean to service interval

 

Effect of the lactation length and the subsequent farrowing rate%

Effect of the Parity of the female on the subsequent farrowing rate

The effect of the Wean to service interval (days) on the subsequent farrowing rate

 

Wean to service interval

The wean to service interval is an important key to successful reproductive management.  Variability in the wean to service interval makes it difficult to reach batch breeding targets and can lead to excessive numbers in subsequent batches – which may lead to a reduction in weaning age as the farm tries to restore batches of pigs.  1st parity sows can have a wean to service interval of 6 days vs. a target of 5 days for older parities.  Note that breeding management decisions may also affect the recorded wean to service interval if no breeding before day 5 or skip breeding, is practiced making analysis difficult.

 

The group of breeding gilts

The gilt has a farrowing rate some 10% lower than a 3rd parity weaned sow which had a lactation length longer than 15 days.

 

The return gilt or sow

The expected farrowing rate of any gilt or sow which fails to become pregnant, falls rapidly with each return to oestrus. 

Gilts which return to oestrus should be mated by AI and naturally with a boar.  If the gilt subsequently returns she should be culled.

Sows which return to oestrus should be culled.  If this is not possible, mate with AI and naturally with a boar.  If the sow subsequently returns she should be culled.

 

Farrowing rate with returns

 

Determining the batch breeding target

When all of the previous conditions are calculated and assessed, a batch breeding target can be created.  This might appear a little tedious, but computer and handheld PDA systems easily accommodate these requirements.

 

For example a farm with 20 batch farrowing places with an average farrowing rate of 85%

The breeding target is therefore a minimum of 25 females a batch (roundup(20/0.85))

 

Breeding pool options

Expected farrowing rate (%)1

Batch A

Winter

Batch B

Summer

Batch C

Winter

# of breeding females from each group

Weaned sows

 

 

 

 

# sows weaned before 15 days of lactation

75

0

0

1

# sows with a wean to service interval ≤ 6 days

87

19

15

16

# sows with a wean to service interval ≥ 7 days

75

0

2

0

Return sows

 

 

 

 

1st return

75

2

3

2

2nd or more returns

60

0

2

5

Gilts

75

4

3

2

Season

 

 

 

 

Summer

75

 

Yes

 

Other times

82

Yes

 

Yes

Number of females bred

 

25

25

25

Expected batch farrowing rate (%)

84

72

76

Expected number of sow to farrow

20

18

19

Is it expected that all the batch farrowing places be filled

Yes

No

No

  1. Expected farrowing rates are farm determined – the numbers used are examples

 

In each of these batches 25 females were bred.  But if the farm had not taken into account the makeup of the breeding pool, the batch farrowing target was not consistently achieved.  In addition farrowing rate of 72% occurred as part of the natural expectancy – not due to any pathogen.  If the farm had followed the traditional approach, the loss of these two batches alone would have cost the farm 2880 kg pork not sold.

 

This link takes you to a spreadsheet where you can examine these options

 

The batch farrowing rate and herd size

Note that the farrowing rate can fluctuate widely as a function of mathematics rather than any pathogenic process.  This is particularly evident in family farms.

 

Sows farrowing per batch

10

30

50

Number of females bred per batch and the resultant farrowing rate if the sows farrowing per batch is achieved

# bred females

Farrowing rate

# bred females

Farrowing rate

# bred females

Farrowing rates

10

100

35

86

58

87

11

91

35

84

60

84

12

84

37

82

62

81

13

77

38

79

64

79

 

On the farm with 10 farrowing batches, the farrowing rate is insensitive to a 7% point change.

On the larger 30 farrowing batch farms, the farrowing rate is insensitive to 2 % point change.

Only on farms larger than 50 farrowings a batch, does the farrowing rate become sensitive to each 1% point change.

 

Pig flow tolerances

 

Role of the cull sow in achieving the batch breeding and pregnancy target

Culling a sow is one of the most important management decisions a producer can make. In taking the decision, the first consideration should be whether the welfare of the sow is compromised. Should this be the case, then the sow should be hospitalized, destroyed or culled immediately.   However, if the sow’s welfare is not compromised, the second question should be "is there is an additional pregnant gilt that will farrow in the same batch”. If not, the sow cannot be culled.

 

Timing of culling

On many farms, sows are culled at the point of weaning. Perhaps the decision is even made during lactation.  This is too late to make such an important management decision.

There are three major times when culling should be considered:

 

Keeping cull sows beyond weaning – batch breeding target reached

Sows need to be culled as they age.  Culling sows after breeding provides options for the farm – it does not stop the culling and replacement of old sows.   When we wean on a Monday, the first day of the new batch should be Tuesday.  Breed all possible sows (including culls) over the next breeding week. Then review the number of females which have been mated.  If the breeding target has been easily met, remove the cull sows the following Tuesday.  Retaining the sow for a week, allows the udder to regress and even possibly some lameness/stiffness issues have been corrected.  In any case, very few farms physically remove the “cull” sow within a week of weaning.  However, during this time she is still eating feed and adding to non-productive days.  The only costs associated with this programme is two AI matings.  If the sow is culled remove her mating from the record. This mating is not to be part of the farrowing rate calculation.  The sow was not mated with the intention of farrowing – she was a cull sow.  She is only retained in the herd as part of the insurance to help guarantee the batch breeding target.

 

Sows kept until pregnancy checking – batch pregnancy target reached

If we retain the sow until pregnancy check (28 days post-mating for example), we ensure that sufficient sows are pregnant before any culling takes place. If sufficient sows are pregnant, do not pregnancy check the sow marked for culling, merely send her to market. The duly culled pregnant sow will not be recognized at slaughter, as 28 day foetuses are extremely small. Culling at this stage brings the additional benefits of recovery from weaning and lactation with the possibility of additional weight recovery. Remove the sow’s mating from the record.  This mating was not to be part of the farrowing rate calculation.  The sow was not mated with the intention of farrowing – she was a cull sow.  She is only retained in the herd as part of the insurance to help guarantee the batch pregnancy target.

 

A possible secondary advantage of these pregnant animals is that through pharmacological abortion, they may be used to fill holes in the future breeding program.

 

Pregnancy diagnosis

Any breeding programme needs to ensure that after day 28 only pregnant sows are retained in the gestation batch.  If the farm adopts a culling post-pregnancy diagnosis method then accurate methods of pregnancy diagnosis need to be employed by the farm.

 

Methods commonly used to diagnose pregnancy in the pig

Detection of oestrus

The primary method of pregnancy diagnosis is that the pregnant sow does not demonstrate oestrus when presented with a boar.  Prior to checking, the test sows should be isolated from all boar contact for one hour, before the attempted detection. 

Ideally, all pregnant sows should be detected for the signs of oestrus for each day of pregnancy – from day 1 to farrowing (around 115 days later).    The peak effort should be concentrated between days 18 to 48 post-breeding.  Regular returns will occur between 18 to 24 days and 36 to 48 days post-mating with peaks at 21 and 42 days post-mating respectively.  Embryonic death, irregular returns, occur between 25 and 35 days post-mating with a peak on day 28 post-mating.

Ultrasound techniques

Doppler Ultrasound

Doppler instruments detect pulsation of arteries or fetal heartbeats.   The probe is placed on the flank of the sow, lateral to the nipples and aimed at the sow’s pelvic area.  After 24 days of pregnancy fremitus develops in the uterine artery which creates a characteristic “whooshing” sound which is heard by the operator.

False positive results occur during proestrus, estrus or active endometritis.  Poor electrical contacts within the instrumentation may create a positive sound.  If the operator tries too hard and puts pressure on the femoral artery creating false fremitus.  Note operator issues if the operator needs hearing aids.

False negative results occur when the examinations are conducted in a noisy environment.

Amplitude-Depth A mode ultrasound

Amplitude-depth instruments use ultrasound waves to detect the fluid-filled uterus.  A positive result can be obtained from around 28 to 70 days of pregnancy.

False positive results occur with detection of a fluid-filled urinary bladder, pyometra, endometrial oedema or abscess. In wet fed sows the large bowel may contain sufficient fluids to give a positive result.

False negative results occur when animals are examined below day 28 or after day 70 of pregnancy as there may be insufficient allantoic fluid to stimulate the instrument.

Real-time ultrasonography

Pregnancy is determined by the presence of distinct fluid filled black vesicles in the reproductive tract or clear evidence of foetal structures – for instance bone.  To reduce the number of false positives it is important to note the presence of the foetus within the black fluid filled vesicle.

False positive result:  If detection is attempted before day 28, positives may include cases of embryonic death which do not farrow, pseudopregnancy, endometritis, pyometra and bladder.

False negative results: Insufficient fluids surrounding foetus – before day 21 and after day 80. 

 

In all cases where an ultra-sound machine is used to assist pregnancy diagnosis, poor machine maintenance and dying batteries will cause false readings both positive and negative.

 

Issues with failing to detect oestrus at 18-28 days

On several farms, poor accuracy of pregnancy diagnosis may be related to failing to detect the natural 10% of bred sows which should cycle before day 28 post-mating.  If these animals are not removed from the remaining “pregnant” pool, the use of machinery results in a large number of sows believed to be pregnant – false positives. If a sow remains in the “pregnant” pool and an empty farrowing place is the result, then 960 kg of pork will not be sold.  This is a significant loss of income and raises the cost of production for the rest of the batch. The impact is obviously dependent on the size of the batch and is more acute in the smaller family farm. These animals are evident in the reproductive records as “culled” in the last weeks of gestation.  The mischaracterization of these sows can lead to serious misdiagnosis of reproductive problems.  A useful tool when analyzing reproductive performance is to note the number of batches where no 3 and 4 week returns are detected by the farm staff.

 

Other methods of pregnancy diagnosis not used in general practice

There are a number of other methods which can be used to determine pregnancy such as rectal palpation and detecting various hormone concentrations.  However, while these may have a role in academic institutions they are not used in the commercial pig industry.

 

Analysis of an unnatural low farrowing rate

When analyzing the farm’s reproductive problems, ensure that all the natural factors discussed above have been taken into account.  Then apply a systematic approach to the problem:

  1.  Ensure that the failure to farrow is associated with a reproductive cause
  2. Assess the timing of the returns to estrus
  3. Determine the cause – female, male (natural and AI) or human error.
  4. Watch carefully, ideally using video recording, the whole mating process.

 

Ensure that the failure to farrow is reproductive

Many failures to farrow problems are not reproductive.  A farm with a water supply problem and high sow mortality associated with cystitis and pyelonephritis will experience a low farrowing rate as majority of sows will die while pregnant.  Remember to assess the whole gestation period for causes of failure to farrow.

 

 

Reason

Target %

Returns to estrus

10

Abortions

0.5 - 1

Not in pig pigs (moved to farrowing house found not pregnant)

0 - 0.5

Culled in pig or found not in pig at pregnancy checking

1

Died in pig

1

Resulting farrowing rate

87

 

 

Failure to farrow investigation

If the failure to farrow has been determined to be associated with reproductive failure.

Analysis of a return to oestrus problem

Once it has been determined that the failure to farrow problems are associated with an abnormal return to estrus or culled for failure to be pregnant; further investigations can be carried out to determine if the cause is infectious or not infectious.


Targets for the type of returns exhibited by sows

 

Type of return

Target %

Regular returns 18-24 and 36-48 days

80

Irregular returns (any other time)

20

 

An understanding of basic early embryonic signaling provides an interpretation of returns to service which can be used to help explain sows which fail to breed and assists in the creation of a differential diagnosis.

 

Early embryonic signals and their influence on failure to maintain pregnancy

 

Day

Event

If event fails

10

Oestrogen sulfate from blastocyst

Female returns at 18-24 days

14-17 and 2 implant per horn

Oestrogen sulfate from the implanted embryo

Female returns at 25-35 days

Embryo dies shortly after day 17 but before day 35

 

Female returns at around 63 days a pseudopregnancy

 

The interesting aspect of this study is that there is no normal physiological reason for a sow to repeat at 36-48 days.

 

This is graphically represented

 

 

 

OeSO4 is oestrogen sulfate

Embryonic signals and their effect on pregnancy maintenance

 

 

Utilising this information, a basic guide to why sows return to service can be compiled.

 

 Major reasons why sows return to service

 

Day of repeat

Reason for return

0-17

Nymphomaniac (follicular cyst - rare).  Not in season initially

18-24

Estrus (failure of blastocysts to reach day 10)

25-35

Embryonic death (failure of 4 piglets to implant). 

Not in season initially

36-48

Missed estrus.  Missed embryonic death + estrus. 

Not in season initially + oestrus missed.

49-80

Pseudopregnancy.  Abortion.  Combinations of above.

80 +

Combinations of above.

 

This implies that a lot of returns to service are poor oestrus detection rather than pathogenic agents, which may be difficult for some stockpeople to accept.

 

Achieving 100kg weaned per batch farrowing place

Once the farm has achieved consistent all-in/all-out in the farrowing area by adopting batching, the farm needs to focus on maximizing the quality and quantity of the number of piglets being weaned to ensure that the required kg meat output targets are achieved.

 

Total born

Over the last decade there has been a revolution in the number of piglets born.  Targets of 12 pigs weaned per batch farrowing place are now commonly achieved.

 

Factors that affect total born

There are a number of factors to consider when looking at total born figures.

Fill all the batch farrowing places

Primarily the number of piglets born is determined by the number of sows which farrow in the batch.  A failure to fill a farrowing place results in 12 pigs not being weaned – which at a deadweight of 80kg is 960kg of pork not sold.

Wean to service interval

The wean to service interval has a dramatic impact on the total born of the subsequent litter.  As with the farrowing rate the optimal time is 4 to 6 days post-weaning.

 

Wean to service interval and litter size

 

Genetic selection

Over the last decade selection pressure has been applied to litter size resulting in tremendous improvements of 2 pigs weaned per farrowing place.  This improvement does not show any indication of slowing down.

 

Change in litter size – total born, born alive and numbers weaned between 1998 to 2008 in Ireland (Data from the Teagasc National Pig Herd Performance 2008)

 

Additional genetic improvements are now in place against diseases – such as pre-weaning diarrhoea – rather than any specific pathogen.  Such measures are resulting in a reduction in pre-weaning mortality and thus increase in numbers and weight of piglets weaned.

However, selection for larger litters is not always a blessing.  If the piglets have low birth weights or are extremely variable, management problems will ensue. Piglets with a birth weight less than 800g are likely to die before marketing.

Gilt acclimatization and isolation programmes

Providing sufficient time for gilts to be prepared to enter the adult breeding herd is a key component.  Selecting gilts from the finishing house from this week’s slaughter group at 120 kg will not provide sufficient time for pathogen stabilization, especially with regards to PRRSv.  Destabilization of PRRSv and other pathogens leads to an increase in the number of weaned pigs lost pre and post-farrowing.

Gilt development programmes

Providing gilts with the body structure, age and reproductive maturity is essential for maximizing gilt litters a key to enhancing total born.  Gilts should be targeted to have a total born of at least 13.5 piglets.

Boar usage

The fertility of the boar can have a tremendous impact on litter size and more emphasis on boar selection and fertility is required. Pooling semen can assist in maintaining farrowing performance, but it should be practiced only with proven sires.

1st parity sow’s gestation and lactation nutrition – second litter size loss

It is absolutely vital that the nutrition of the gilt is optimized with minimal weight loss in the first lactation.  The wean to service interval in first parity sows is often extended by 1 day when compared to multiparty sows.  This naturally reduces the potential litter size and farrowing rate.  However, it is essential that the 2nd litter is at least 0.5 pig larger in total born than the 1st litter and that the 3rd litter is a whole pig more than the 2nd litter.

Parity profile

The correct parity profile is essential for long term survivability.  The most productive parities are parities 3 to 6.  These parities should compose of 46% of the pigs on the farm to maximize weaning numbers and weight.

 

Parity structure and total born targets

Parity

Gilt

Parity 1

Parity 2

Parity 3 to 6

Parity 7

% of herd

17

14

14

46

8

Total born

 

13.5

14.0

15.0

14.5

 

Calculate your own parity profile

 

Management of the breeding and gestation pool

Many farms have suboptimal litter size related to the management of the pregnant sow in the first 28 days of pregnancy.  Any unnecessary stress, for example moving into a different pen or stall, can result in lost fetuses.  This may be seen as a loss of total born.

Day of farrowing – Monday

With litters of 15+ total born, it becomes more critical that stockmanship is directed towards the care and management of the litter at birth.  This is especially with regard to the consumption of colostrum by each piglet within 6 hours of birth.  Ideally the peak farrowing day should be towards the beginning of the week so that the staff is given the best resources to manage the piglet’s first few days of life.  If the sow’s peak farrowing day was on Monday, this would mean that the sows would have to be bred on a Friday (some 115 days earlier).  The consequence of this is that the batch would have to be weaned on a Monday – for a 4 day wean to service interval.   The added advantages of weaning on Monday, is that with breeding occurring on Friday and Saturday, AI semen would be freshly delivered and this would enhance litter size further.  With the larger number of weaned pigs, weaning on Monday provide the best stockmanship to these weaned pigs.  Enhancing the newly weaned pig’s feed intake in the first week post-weaning is a critical component to successful finishing.

Traditional weaning has occurred on a Thursday so that breeding management was optimized.  With breeding systems utilizing AI and boar exposure systems, two stockpeople can breed 50 females an hour, making breeding efficient and quick.  The need for breeding to occur at peak man-hour times during the week has passed.

Genetic manipulation

Early studies using DNA vaccines to reduce foetus loss in gestation

Management of the lactating sow

Any investigation into the weight of the litter weaned needs to encompass not only the reproductive management of the gilt and pregnant sow, but also the stockmanship and management of the pigs in the farrowing area. The quality of colostrum and its availability for each pig retained after farrowing.  Farrowing rooms should be designed to minimize hyoglycaemia and hypothermia in newborn piglets and maximize the feed intake and milk production by the lactating sow.  All of these factors play a vital role in ensuring maximum productivity from the farrowing area.

 


 

Suggested targets for reproductive performance

 

 

Target

Interference

Breeding and gestation

Age at first service (days of age)

> 220

< 220

Weight at first service (kg)

> 130

< 120

Weaning to service interval (days)

4 to 6

< 3 > 7

Farrowing rate (%) (depends on herd size)

> 82

< 80

Regular returns (%)

< 6

> 8

Irregular returns (%)

< 3

> 5

Negative pregnancy test (%)

< 2

> 3

Abortions (%)

< 1

> 3

Failure to farrow (%)

< 0.5

> 2

Culled while pregnant (%) (not management culls)

< 1

> 2

Farrowing

Total pigs born/litter

> 14

< 12

Pig born alive/litter

> 13

< 11

% stillborn

< 7

> 10

% mummified

< 3

> 5

Litter scatter (litters less than 7 pigs) (%)

< 15

> 15

Weaning

Pigs weaned per farrowing place

> 11.5

< 10

Weaning weight at 27 days (kg)

< 8

< 7

Population (on an annual basis)

Average parity

3.5

<3 and >4

Replacement rate (%)

< 40

<35 and >45

Culling rate (%)

30

<28 and >40

Mortality rate (%)

5

>10