Abstract: A Welfare-Focused Fattening Barn in Synergy with a Methanation Unit

Type and Average of Pigs on the Farm

The farm maintains 330 sows and their offspring through to slaughter.

Farming System

Intensive production system.

Description and Evaluation of the Good Practice

Inaugurated in 2021, this 1,920-place fattening building reflects a holistic approach in which animal welfare, technical and economic performance, health management and working conditions are considered inseparable, creating value at farm-system level by combining the building with an on-farm methanation unit. The building comprises eight rooms of 240 places each, divided into eight pens of 30 pigs, each equipped with four V-shaped scrapers that separate the solid and liquid fractions of manure. The solid fraction is removed daily to the methanation unit and converted into biogas through cogeneration, with the heat partly reused to preheat incoming air through aerothermal units, improving the indoor environment. A distinctive welfare element is the automated daily distribution of chopped straw onto a solid surface covering 15% of each pen, which stimulates the pigs' interest while also acting as a substrate recoverable through methanation. Another pillar is increased space per animal — 0.84 m² per pig compared with the regulatory 0.65 m² — reflecting a sustainable investment offset by technical and comfort gains.

Farm Context

• Pigs: Providing more space per pig allows the animals to express natural escape behaviours, reducing conflict between pen mates.
• Environmental Enrichment: Chopped straw is automatically distributed daily, at approximately 30 g per pig, onto the solid surface covering 15% of the pen, in addition to wood and a chain.
• Housing and Management Characteristics: The building has 8 rooms of 8 pens of 30 pigs each (1,920 places), with 0.84 m²/pig at a maximum weight of 110 kg. The floor is partly slatted, with 15% solid flooring for straw provision. The design accounts for maintenance, with accessible ducts and dedicated lighting, and scraper monitoring is scheduled every two weeks.
• Management Practices: Regular manure scraping and solid/liquid separation, combined with controlled ventilation and large openings fitted with UV filters, contribute to better air quality and a healthier indoor environment for the pigs.

Economic Analysis

Building cost was €767 per place before 2021, of which approximately €150 related to the scraping system. According to the farmer, the additional cost is worthwhile given the gains in performance and health. Results show a 3.6% loss rate in fattening, a daily weight gain of 882 g, and a feed conversion ratio of 2.51 from 30–115 kg. The farm is registered under a collective higher-level pork production standard, under which pigs are paid a price linked to production costs, helping finance the investment.

Environmental Analysis

The combination of frequent scraping, solid/liquid manure separation and methanation significantly reduces greenhouse gas and ammonia emissions while improving manure quality. The solid fraction contains 30–50% more dry matter than untreated slurry, facilitating methanation and reducing the volume of slurry to be stored. Overall greenhouse gas reduction, including methane, is estimated at approximately 40–80%, while ammonia emissions are reduced by around 25% compared with conventional scraping systems without treatment.

Replicable Benefits and Relevance for Other EU Countries

This concept shows the benefits of integrating high welfare standards at building and farm-system level, with the fattening building and methanation unit designed as a coordinated system. The technologies used are well established and can be adapted to a farm's needs, though partial slatted floors with automated straw distribution are easier to implement in new constructions. Return on investment can be partly justified through energy recovery and improved performance, though the cost per place is significant and may require additional incentives.