During recent visits to several farms, I observed the challenges associated with an ageing sow herd. Many of these farms had too many older sows, which led to noticeable declines in productivity, increased health issues and difficulties in herd management.
Sometimes we overlook the problem, believing that retaining experienced sows maintains stability. However, the reality is quite the opposite. The excessive number of old sows results in lower reproductive efficiency, higher culling rates and greater susceptibility to diseases.
Parity structure in a pig herd is a critical factor influencing overall productivity, profitability and health. The parity structure refers to the distribution of sows across different reproductive cycles, with an ideal herd consisting of a balanced mix of young and older sows.
The most productive herds have parity structures with a high proportion of sows with the intermediate number of farrowings (three to five), which indicates the ability to retain young sows.
“Production data clearly shows that sows beyond their sixth parity experience a 15-20% drop in litter size and increased stillbirth rates, significantly reducing overall piglet output.”
Replacement rate
A well-managed pig herd typically requires an annual replacement rate of 40–45% to maintain optimal productivity and parity balance. This ensures a steady introduction of younger gilts while phasing out the older, less-productive sows before their performance declines significantly.
One of the primary concerns with keeping too many older sows is reduced reproductive efficiency. As sows age, their fertility declines, leading to lower conception rates, decreased heat intensity, irregular oestrous cycles and difficulties in achieving successful mating.
Production data clearly shows that sows beyond their sixth parity experience a 15-20% drop in litter size and increased stillbirth rates, significantly reducing overall piglet output. This decline in productivity reinforces the need for strategic culling and gilt replacement.
As sows age, their susceptibility to health problems increases. Common health concerns include lameness, which reduces their ability to stand and nurse properly.
There is also a higher risk of culling due to prolapses, as uterine and rectal prolapses become more common in older sows. Furthermore, aged sows have a weakened immune response, making them more susceptible to infections, mastitis and other diseases that can affect lactation and piglet survival.
They produce lower quality and quantity of colostrum, which is crucial for piglet immunity. Weaker milk let-down can compromise piglet health, increasing pre-weaning mortality due to malnutrition.
Maintaining too many older sows in the herd can create bottlenecks in the replacement process. If older sows are retained too long, fewer opportunities arise for younger gilts to enter the breeding herd, disrupting the overall parity balance.
Ideal parity structure
A well-managed parity structure ensures a smooth and continuous transition from older sows to younger gilts, maintaining herd productivity.
Introducing a higher number of gilts into the herd can pose health challenges and destabilise herd health. Gilts may bring new pathogens or have lower immunity compared to older sows, increasing the risk of disease outbreaks.
The transition period can be stressful, leading to suppressed immune responses and greater susceptibility to infections. Additionally, gilts may require different nutritional and management strategies to ensure successful acclimatisation.
Proper health monitoring, vaccination protocols and biosecurity measures are essential to minimise risks and ensure that the introduction of gilts strengthens rather than weakens overall herd health.
To mitigate the risks associated with too many old sows, producers should aim for an ideal parity structure. Regular culling based on performance is essential, rather than waiting for sows to become unproductive.
Sows should be culled based on reproductive efficiency, litter size and health condition. Strategic gilt introductions should be maintained to replace ageing sows and ensure a balanced parity distribution.
Monitoring parity data is crucial to track sow performance across different reproductive cycles and establish clear benchmarks for replacement decisions. An ageing sow herd presents numerous challenges, including reduced reproductive efficiency, higher health risks, lower mothering ability and increased management costs.
By maintaining a well-balanced parity structure and proactively replacing older sows, producers can sustain high levels of productivity, enhance animal welfare and improve overall farm profitability.
Implementing strategic culling and gilt replacement practices will help ensure the herd remains efficient, healthy and capable of maximising piglet output year
after year.