Individual tracking shows free-range hens roam best with more space outdoors
The animal article of the month for January is ‘Outdoor stocking density in free-range laying hens: radio-frequency identification of impacts on range use‘. Authors: D. L. M. Campbell, G. N. Hinch, T. R. Dyall, L. Warin, B. A. Little, C. Lee.
Consumer preferences within Australia have driven the increase in free-range laying hen systems as they are perceived to improve hen welfare. These free-range systems vary from small-scale producers housing hens in mobile caravans with access to extensive open spaces to larger-scale producers housing hens in fixed sheds with less outdoor space per individual hen. Australian consumers have felt misled by the ‘free-range’ label, paying a premium for perceived housing conditions, thus leading to successful lawsuits against some free-range farms. In response, the Australian Consumer Affairs Ministers released an egg labelling information standard in March 2016, requiring eggs to have the hen’s outdoor stocking density stated on the label and a maximum density of 10 000 hens per hectare. However, both in Australia and internationally, there is a lack of research determining how much outdoor space hens prefer. Free-range outdoor stocking density is different to stocking density in closed indoor systems. Hens have a choice whether they access the range or not, leading to continually varying outdoor stocking densities throughout the day. Our experiment was thus set up to ask, if we provide hens differing space outside, do they vary in how often they use the range?
Using an experimental free-range facility, we set up six pens with identical resources indoors, but with outdoor ranges of three different sizes simulating three outdoor stocking densities of 2000, 10 000 or 20 000 hens per hectare. In our six small flocks we placed microchip leg bands on 50% of the hens and used radio-frequency identification technology to track individual hens travelling through the range-access pop holes. Across a period of 15 weeks, we determined how long individual hens spent outdoors each day, the length of their range visits and what percentage of available ranging days hens went outside. Using video recordings we also determined across the day, on average, how many birds were outside simultaneously.
Our data showed that hens with more space outside spent a longer portion of the day using the range with longer individual visit times. In all outdoor densities, 38% to 48% of hens used the range daily, but there were 2% of hens that chose to never go outdoors, and other hens did not start using the range until several weeks after the pop holes had first opened. On average, approximately half of the hens were outside simultaneously across all outdoor densities.
This research showed that outdoor space can impact how often hens use the range and actual preferred outdoor densities are much lower than stated densities as birds do not use the range simultaneously. Further research of ours looked at the implications for hen welfare in these flocks, including the behaviours they exhibited on the range and overall hen health.
If free-range systems are to be implemented sustainably, more studies are needed to determine how domesticated hens adapt to outdoor ranging, whether free-range systems do improve hen welfare and why individual hens within a flock vary so greatly in their use of the range.
This article is freely available for one month:
Authors: D. L. M. Campbell, G. N. Hinch, T. R. Dyall, L. Warin, B. A. Little, C. Lee.
The animal Article of the Month is selected by the Editor-in-Chief and is freely available for one month. View the recent selections