Introduction In recent years, farmers and consumers have exhibited growing interest in loose-housing systems for pigs. Whilst these systems are implemented in other production stages, their application in finishing pig production remains limited. Recent technological developments such as automatic sorting systems, have eased the management of large groups of pigs, potentially supporting the broader adoption of loose-housing systems. This study explored how Swedish farms have managed novel automatic sorting systems within loose-housing setups for finishing pigs. Material and methods Data were collected at two time points—early and late within one production batch—across seven farms housing 155–460 pigs. Information regarding pen layout, environmental conditions (CO 2 and NH 3 concentrations, temperature, and floor hygiene), and animal-based welfare indicators (skin lesions, manure on the body, tail lesions, and tail posture) was collected. Additionally, semi-structured interviews were conducted and analysed thematically. Result and discussion Two overarching themes emerged from the interviews: “ Levers ” and “ Barriers ”. Under Levers , farmers described the system as an innovative and consumer-friendly solution that enhanced animal welfare by supporting natural behaviours, including increased locomotion and opportunities for self-directed activity. Identified Barriers included management challenges associated with large-group housing, particularly increased risk of disease transmission and greater complexity in daily routines. Management within the sorting system emerged as a recurring sub-theme, with differences in pen design and routines influencing straw provision, cleaning and daily work. Air quality varied considerably across farms, with CO 2 levels ranging from 597 to 2806 ppm and ammonia levels between 0.38 and 18 ppm. Linear regression analyses revealed significant increases in ammonia concentrations between visits on five farms, while consistently high NH 3 levels (13 ppm) on the others. Pig soiling increased significant from early to late visits based on cumulative link mixed model analysis. Skin lesions were common during early visits but declined significant later in the production period. Between farm variation were found for animal-based welfare indicators using a Wilcoxon rank-sum test. Tail lesion prevalence varied, ranging from none to 82% of pigs across farms. All studied farms exhibited unique pen designs and diverse management practices, highlighting the flexibility and developmental phase of the sorting system.
Karlsson et al. (Thu,) studied this question.