Temporal evolution of Sow herd age structure and its impact on the performance of Spanish commercial farms

Abstract Background Efficient herd management is crucial for maintaining constant pig production. This study analysed the evolution of census structure over time and how productive performance variables related to farm efficiency are affected and evolved, using data from 427 Spanish commercial pig farms over three years (2020–2022). Farms were classified into three types of herd age structures based on the first coefficient of a quadratic function representing sow parity distribution. A longitudinal analysis was performed to evaluate changes in herd age structure and productivity over time, applying repeated measures ANOVA. Results The herd age structure types in 2020 were: HS1 (with a downward-concave trend), HS2 (with a trend close to a straight line), and HS3 (with an upward-concave trend). HS1 farms had the highest productivity over time, maintaining superior performance compared to HS2 and HS3 (p < 0.01), with 31.4 piglets weaned per sow per year in 2021 and 30.9 in 2022. However, HS1 farms showed moderate consistency in herd parity structure over time, with 48.6% remaining in the same group in 2021 and 43% in 2022. HS2 farms showed the greatest herd parity structure stability over time, with 60.1% and 54.5% of farms remaining in this group in 2021 and 2022, respectively. HS3 farms were the least stable, with only 29% retaining their classification by 2022, and had the lowest productivity. Conclusions Classifying farms by herd age structure provides valuable insights into how parity distribution influences farm productivity over time and how herd parity structure evolves. HS1 farms achieved the best productivity over the study but require specific management practices to maintain their stability. HS2 remained with the most stable herd structure over time, with intermediate productivity, while HS3 farms showed the worst stability and performance. Thus, HS1 is recommended as the optimal herd age structure for maximizing productivity in the short and medium term. Further research should focus on identifying specific management factors to optimize productivity and ensure long-term herd structure stability of HS1.