Knowing when to cull sows and why is an important part of herd management. This information will help you develop a good culling policy.
Why is culling important?
A good culling policy with a sound understanding of when to cull is an integral part of herd management. It maintains a steady flow, replacing the less productive sows on a regular basis, without disrupting the overall performance of the breeding herd.
Income from cull sows should not be a major factor in determining the culling policy, as it should only account for about 2% of total sales income.
Culling rates impact the economic efficiency of a breeding herd. When the culling policy is not adhered to and older sows are retained, herd productivity will fall.
The cost of empty days
Total annual breeding herd expediture
(Productive sows x 365)
Cost per sow-day x empty days per annum
Pigs born alive (sold) per sow per year
Common reasons for culling
Voluntary culling (selected)
This helps manage the parity profile. You will need to decide what your target maximum parity is for each animal and stick to it.
Voluntary culling is also carried out to remove any sows identified as having sub-optimal performance. These sows may have shown:
- Farrowing difficulties
- Poor litter size
- Poor lactation and rearing ability
- Poor maternal behaviour
- Decreased productivity compared with the herd average
Involuntary culling (forced)
If too many sows are culled for involuntary reasons, especially from the first two parities, it can affect staff morale and could be an indicator of reduced sow welfare.
Typical reasons for involuntary culling include:
- Failure to conceive (recommended after two failed attempts)
Other reasons for culling
If a sow loses her appetite, looks unwell and has black or dark dung, it may be a sign of stomach ulcers.
Sometimes, sows are also seen being sick and generally do not perform well. Ulcers require veterinary diagnoses and, often, more than one sow will be affected.
If there is a problem with stomach ulcers, increasing the amount of fibre in the diet can help; coarseness of the diet should also be assessed. Discuss any concerns with your nutritionist.
Shoulder sores can be extremely painful and lead to reduced wellbeing, feed intake and productivity.
They are often a sign of poor body condition management, problems with the flooring and small/poor farrowing crates but can also be found on old or ill sows.
Affected sows should be treated according to your veterinary protocol and moved to a hospital/recovery pen depending on severity. Identifying at-risk sows and addressing any potential contributing factors are key.
How to reduce involuntary culling
A good way to avoid involuntary culling is to ensure optimal gilt selection for improved sow longevity.
It may also be appropriate to consider a ‘skip-a-heat’ policy.
There are also some practical things you can do to help support good body condition scores and avoid issues with lameness, which can reduce feed intake.
Support good body condition scores
- Maximise feed intake during lactation. This will help reduce body condition loss
- Body condition score sows and feed individually after farrowing and during gestation, where possible
- If feeding individually is not possible, feed on a group basis after sorting by condition
Take precautions against lameness
- Check legs and feet after each farrowing cycle; even slight lameness can reduce feed intake due to reduced ability to compete for feed (groups) or reduced ability and desire to walk to feeder
- Ensure floors are not slippery to avoid hip, feet and leg injuries
- Check that all sows get up and walk about when inspecting animals
- Move any lame, ill, non-eating or bullied sows to a hospital/recovery pen
Discuss veterinary protocol with all responsible staff, and euthanise sows with severe injuries. Euthanising sows should only be done by staff trained to do so or by the vet.
Record all cull sows and the reasons for culling. Use these records for monthly reviews of sow welfare and performance, and discuss with your vet.
Should a sow have another litter?
At weaning, check that sows meet the following criteria:
- Good overall health
- No shoulder sores or other injuries
- Body condition score of 3
- Good conformation, e.g. gait and feet
- At least 12 functional teats, with no udder diseases or dysfunctions
- Good temperament
Decide how many of the above points need to be met before the sow continues to her next litter. Continually assess the checklist and aim to meet more of the criteria over time.