By Maile Matsimela
The commercial egg industry worldwide has faced increasing scrutiny regarding animal welfare practices, particularly concerning the housing systems used for layer hens.
Traditional battery cages, which have dominated egg production for decades, severely restrict natural behaviours, such as perching, dust bathing and nesting. These restrictions lead to poor bone strength, metabolic disorders and significant welfare concerns that have prompted many countries to phase out conventional cages.
In South Africa, the poultry industry has recognised these challenges but lacks sufficient research on alternative housing systems under local commercial conditions. This knowledge gap has hindered evidence-based improvements in hen welfare while maintaining production efficiency.
A recent pioneering study by the Department of Science and Technology at the University of Pretoria, published in the South African Journal of Animal Science 2025, Volume 55 (3), addresses several critical issues.
The study, conducted on a South African commercial farm, addresses this critical need by examining commercial layer hen behaviour in two alternative housing systems (floor systems and enriched cages), focusing on welfare implications and productivity outcomes. Enriched layer hen cages (also known as furnished or colony cages) are modern housing systems for egg-laying hens that were designed as an improvement over traditional battery cages.
Researchers compared the behaviour and welfare of 27-week-old hens housed in enriched cages with 47-week-old hens in floor systems. The study focused on key natural behaviours that indicate welfare status, including dust bathing, nesting, perching and feather pecking. What set this research apart was its innovative dual-observation approach, employing both trained human observers and video recordings to capture behavioural data with unprecedented accuracy.
Physical welfare indicators
Physical welfare indicators were meticulously monitored throughout the six-week trial period. Researchers scored body condition and plumage quality, while also measuring a previously underreported welfare issue: the formation of mud balls on hens’ feet in floor housing systems. These hardened mud accumulations can significantly impair mobility and prevent natural behaviours, yet have received little attention in welfare assessments.
Statistical analysis employed Spearman’s rank correlation to explore relationships between behaviours and physical parameters, like body weight, providing insights into the complex interactions between welfare and productivity – a crucial consideration for commercial producers contemplating housing system transitions.
The research uncovered striking differences in behavioural expression between the housing systems. In floor systems, 79.2% of hens engaged in dust bathing, with sessions averaging 22.63 minutes. This natural behaviour, which helps maintain feather condition and control parasites, is completely prevented in conventional cages and was found to be hindered by mud ball formation in floor systems.
Perching behaviour showed remarkable variation, with 100% of hens in enriched cages utilising perches compared to 75% in floor systems. This finding has significant implications for bone strength and welfare, as perching is a fundamental natural behaviour that promotes skeletal development and provides escape from aggressive encounters.
The study went on to reveal that feather pecking, a damaging behaviour associated with stress and poor welfare, was more prevalent in floor systems (58.3%) than in enriched cages (35.4%). Importantly, researchers discovered a negative correlation between feather pecking and body weight in enriched cages, highlighting a direct link between behavioural welfare indicators and productivity measures.
Nesting behaviour also showed system-dependent patterns, with higher nesting box usage in enriched cages (93.75%) compared to floor systems (75%). A positive correlation emerged between nesting behaviour and body weight, further reinforcing the connection between the fulfilment of natural behaviours and production outcomes.
Perhaps one of the most concerning findings was the high prevalence of mud ball formation in floor systems. By the end of the trial, 41.67% of hens had developed large mud balls exceeding 3cm in diameter on their toes. These formations significantly restricted movement and prevented natural behaviours, creating a previously underappreciated welfare challenge in floor housing systems.
Body weight trends reinforced the complex welfare picture. Hens in enriched cages gained weight over the trial period, increasing from an average of 1.83kg to 2.14kg. In contrast, those in floor systems experienced a slight decrease from 2.10kg to 1.90kg. These findings suggest that while floor systems offer certain behavioural freedoms, they may present other welfare challenges that affect physical condition.
The study also demonstrated the limitations of traditional monitoring methods. Video surveillance captured 57.9% more feather-pecking events than human observers, underlining the critical value of automated monitoring systems for accurate welfare assessment in commercial settings.
Recommendations
Based on these findings, the researchers developed comprehensive recommendations for improving hen welfare in commercial settings. They advocate for a transition from conventional cages to enriched systems that allow natural behaviours while maintaining production efficiency. For farms using floor systems, the study emphasises the importance of providing adequate perch space, appropriate stocking densities, and improved litter management to promote dust bathing and reduce mud ball formation.
The research strongly supports implementing video-based monitoring in commercial operations to identify early stress indicators and welfare issues that human observation might miss. For the specific challenge of mud ball formation, the researchers recommend minimising water spillage in floor systems and establishing regular monitoring and cleaning protocols.
Education and training emerge as crucial components of welfare improvement. Farm staff require training to accurately observe and score welfare parameters, while broader awareness of enriched housing benefits needs promotion among producers and industry stakeholders.
This groundbreaking study opens numerous avenues for future research. The complex interactions between behaviours, housing systems and productivity merit further investigation, as do the effects of environmental enrichment on stress reduction and immune function. Additional welfare indicators, such as keel bone fractures and long-term physiological impacts, require evaluation alongside the economic implications of welfare improvements.
Important research
The significance of this research extends beyond its immediate findings. As the first field study in South Africa to assess layer hen behaviour under commercial conditions using both human and video-based observations, it provides quantitative evidence on the prevalence of natural behaviours in different housing systems and establishes important correlations between behavioural expression and physical parameters.
By balancing welfare considerations with production efficiency, this research contributes valuable knowledge that can help transform commercial egg production in South Africa and beyond. It offers evidence-based insights to inform industry practices during the transition away from conventional cage systems, potentially improving the lives of millions of laying hens while maintaining the economic viability of egg production.
The study’s holistic approach to welfare assessment, combining behavioural observations with physical measurements and productivity indicators, provides a model for future research and a foundation for policy development.
As consumer demand for higher welfare standards continues to grow globally, this research offers timely and relevant guidance for an industry in transition, helping to create a more sustainable and welfare-friendly future for commercial egg production.
Also read:
