# Valorisation of Culled Iberian Sows Through the Montanera System: Immunocastration, Welfare and Sustainable Production

## TL;DR

This study shows that culled Iberian sows can be turned into high-value premium pork products using a traditional acorn-based system and immunocastration, improving animal welfare and sustainability.

## Contribution

The study introduces a novel approach combining immunocastration and montanera finishing to valorize culled sows while maintaining meat quality and welfare.

## Key findings

- Immunocastration did not negatively affect growth or meat quality in culled Iberian sows.
- Both vaccinated and non-vaccinated sows produced high-quality meat suitable for premium products.
- The approach transforms low-value culled sows into high-value products with economic and environmental benefits.

## Abstract

Breeding sows are typically sold at very low prices when culled. This study investigated whether these animals could generate higher value when finished in the traditional acorn-based system for premium Iberian pork. We also investigated immunocastration, which temporarily stops reproductive activity and could improve management and welfare. Thirty-six Iberian sows were divided into two groups: one vaccinated and one non-vaccinated. Following an adaptation period, all animals grazed on acorns and natural pasture before slaughter. Results showed the vaccination did not affect growth or meat quality, and both groups produced excellent meat suitable for premium products. Economic analysis revealed that this approach can transform low-value animals into high-value products, providing farmers with a profitable strategy that also benefits animal welfare, reduces environmental impact, and preserves the traditional management of Iberian pig production.

Despite their substantial contributions to herd productivity, culled sows typically receive minimal economic valorisation. This study evaluated the feasibility of finishing culled Iberian sows under free-range conditions (montanera finishing system) and assessed the effects of immunocastration on productivity, welfare, and meat quality. Thirty-six culled Iberian sows were assigned to two treatments: entire sows (n = 18) and immunocastrated sows (n = 18). Following a maintenance phase and a pre-finishing transition, animals were finished under montanera conditions with ad libitum access to acorns and pasture. Productive traits, welfare indicators, carcass traits, and meat quality parameters were evaluated. Immunocastration effectively suppressed reproductive function without compromising productive traits or meat quality in culled Iberian sows. Both groups exhibited comparable body weight evolution, carcass characteristics, and meat quality attributes consistent with Iberian standards. The results indicate a clear potential for value generation, transforming animals from minimal-value culling categories to premium montanera products. This integrated approach combining immunocastration with traditional extensive finishing systems provides a viable way to add value to culled sow valorisation within circular economy frameworks, addressing economic, environmental, and welfare challenges of sustainable livestock production.