Why does parity structure matters?
Each parity stage from gilts (parity 0) to older sows (parity 6+) has different impact on farm’s performance. Gilts and first-parity sows typically have lower litter sizes and higher pre-weaning mortality, while middle-parity sows (parity 3–5) exhibit peak productivity. Older sows often show declining performance, usually with high number of mommies, stillborn, and preweaning mortality, also has an increased risk of culling due to health or structural issues. An imbalanced parity structure can lead to reduced average litter size, increased litter mortality, higher replacement costs, inconsistent pig flow, among others
Is there a single universally optimal parity structure that fit all herds?
Most experts suggest that the most productive herds maintain:
20 to 25%
(parity 0)
36 to 37%
sows in parities 1-2
32-38%
sows in parities 3–5
5 to 10%
sows in parities 6+
This distribution ensures a strong core of high-performing sows while minimizing the risks associated with early or late parity stages.
At this point, it is worth asking whether a single parity structure can be universally applied across all farm types. Making accurate predictions is highly complex due to the variability in farm operations and economic conditions. Therefore, the scenario presented here reflects a generalized framework and is not intended to serve as a definitive solution for every farm context.
Impact of poor parity management
Keeping sows for fewer than three parities results in negative economic value while extending sow longevity improves return on investment, especially when gilt replacement costs are high. As a rule, you need at least three farrowings from each sow to break even investment costs. It is tempting and usually a mistake to keep 8 and 9 parities sows in herd. These old sows have a higher risk of being culled, higher rates of mummies and stillborn. Furthermore, older animals produce less milk, and the physiological deterioration associated with advanced age can increase the risk of pre-weaning mortality. Also, these old sows have the lowest breeding value in the herd.
It is essential to understand that optimizing the parity structure alone does not automatically mean the herd will be more productive. Performance gain is realized by optimizing the use of the genetic merit of the sows with herd management practices, including precision nutrition, strategic health protocols, reproductive efficiency strategies, animal welfare, among others.
Some strategies to achieve better parity structure
- Select gilts based on genetic potential, structural soundness, and appropriate age and weight.
- Ensure proper acclimation and nutrition to minimize the losses of parity 0 to parity 2 sows, to increase sow retention rate, and to improve longevity and performance.
- Plan removals based on parity performance and herd goals.
- Target culling after parity 6 or 7+ for economic efficiency, be very critical on any sow after parity 7+.
- Use herd management software to monitor parity trends and forecast replacement needs.
- Track metrics like pigs weaned per sow per year, farrowing rate, and return-to-estrus rates.
- Collaborate with Topigs Norsvin to match replacement strategies with line-specific longevity and productivity traits.
Gonzalo Martinez, Global Genetics Specialist
Final remark
In my view, there is no single “magic” parity structure that fits all farm conditions. Achieving high retention rates from parity 0 to parity 2 is critical, as it significantly influences the development of a parity distribution that supports efficient and sustainable production. While maintaining a higher proportion of older sows may appear beneficial in the short term, this approach can negatively impact pig flow, profitability, and herd dynamics over time. Also, it will negatively impact genetic progress and herd stability. By focusing on modern gilt development and sow management, implementing smart culling strategies, and decisions based on data, producers can build a sow herd that consistently delivers high performance.