Study links pig feeding strategy to lesions and growth outcomes
Bottom line
Version 1
A new study in Animals reports that feeding strategy mattered more than pen size for several welfare outcomes in finishing pigs. In the 12-week randomized 2 × 2 factorial trial, researchers compared pigs kept in groups of 9 or 18 and fed either ad libitum or a mildly restricted ration at a constant floor space allowance of 1.15 m² per pig. Across most of the study period, pigs on the restricted ration had lower rates of ear and tail lesions than pigs fed ad libitum, while pigs in the smaller groups showed higher daily weight gain and final body weight. The paper was published April 28, 2026, by researchers from the Norwegian University of Life Sciences and collaborators. (mdpi.com)
Why it matters: For veterinary professionals advising swine operations, the findings add to a growing body of evidence that feeding management and competition around feed access can shape both welfare and production outcomes. Earlier Norwegian field work from some of the same research group found that larger group sizes on commercial farms were associated with less ear and body biting but also lower daily weight gain, while recent literature has also pointed to group size as one factor in tail-biting risk, especially in systems that avoid routine tail docking. This new controlled study suggests that even mild feed restriction may reduce damaging behaviors, but any practical application would need to be weighed against growth targets, feeder design, space allowance, and the risk of creating new competition points in commercial barns. (researchgate.net)
What to watch: Watch for follow-up work on how feeder design, enrichment, and stocking conditions interact with mild feed restriction before producers translate these results into broader on-farm feeding changes. (mdpi.com)
Version 2
A newly published paper in Animals examines a familiar tension in pig production: can producers reduce harmful behaviors without giving up too much performance? In a 12-week controlled study, researchers tested two group sizes, 9 or 18 finishing pigs, alongside two feeding strategies, ad libitum or mildly restricted feeding, and found that restricted-fed pigs had fewer ear and tail lesions through much of the trial, while pigs in smaller groups posted better growth. The article, “Welfare and Performance of Finishing Pigs Kept at Two Group Sizes on Ad Libitum vs. Restricted Feeding,” was published April 28, 2026. (mdpi.com)
The work builds on earlier questions around how group housing, feeder competition, and stocking conditions affect pig welfare. Prior field research from Norway, published in Applied Animal Behaviour Science in 2023, linked increasing group size on commercial farms with lower daily weight gain and fewer ear and body bite marks, while pigs also showed more avoidance of a novel human as group size increased. Broader reviews have found that the effect of group size alone is often inconsistent unless it is considered together with feeder access, floor space, and feeding system. (researchgate.net)
According to the Animals listing, the new paper used a randomized design with 16 partially slatted pens and maintained floor space at 1.15 m² per pig. Half of the pigs within each group-size treatment received feed ad libitum, while the others received a mildly restricted ration. The abstract indicates that, except in week 1, restricted-fed pigs showed proportionally fewer pigs with ear lesions and tail lesions, suggesting that a modest reduction in feed availability may have reduced some damaging social behaviors rather than worsening them. At the same time, the smaller-group pigs had higher daily weight gain and higher final body weight, pointing to a production advantage for lower group size under the conditions tested. (mdpi.com)
That result lands in a nuanced evidence base. A recent Animal Welfare paper noted that the European Food Safety Authority has identified group size as a relevant factor in tail-biting risk, particularly in systems where routine tail docking is not used. Other published work has suggested pigs can adapt feeding behavior as group size rises without always losing performance, but those outcomes depend heavily on feeder space, enrichment, and stocking density. In other words, neither “bigger groups” nor “restricted feeding” is likely to be a universal answer outside the specific housing and management context. (cambridge.org)
I did not find a separate institutional press release or independent expert commentary specifically addressing this April 2026 paper. What I did find was relevant background from the same research network and adjacent literature, which consistently frames biting behavior as multifactorial, with feed access, space, and enrichment all contributing to risk. That makes the new study useful less as a stand-alone prescription and more as a controlled signal about where management pressure points may lie. (researchgate.net)
Why it matters: For veterinarians working with swine clients, the study offers a practical reminder that welfare indicators and performance metrics may move in different directions. Mild feed restriction appeared to improve some lesion-based welfare measures, but smaller groups still outperformed larger ones on growth. That means herd health recommendations may need to be more tailored: if a farm is struggling with ear or tail biting, the solution may involve not just ration strategy, but also feeder availability, space allocation, environmental enrichment, and close monitoring for unintended effects on weight gain or competition. In systems that keep tails intact, that balancing act becomes even more important. (mdpi.com)
What to watch: The next question is whether these findings hold up in commercial settings with different feeder designs, genetics, and enrichment programs, and whether producers can capture the welfare benefits of lower lesion rates without giving up too much finishing performance. More field validation, especially in intact-tail systems, will likely determine how influential this paper becomes in practice. (researchgate.net)