1m. Aerial perches improve the welfare of laying hens and are now recommended by the European Union
Submitting InstitutionsUniversity of Edinburgh,
Unit of AssessmentAgriculture, Veterinary and Food Science
Summary Impact TypePolitical
Research Subject Area(s)
Biological Sciences: Zoology
Medical and Health Sciences: Neurosciences
Summary of the impact
Impact: Policy / animal welfare. Policy implementation changed and
bird welfare improved.
Significance: Our research informed welfare guidelines impacting
upon housing of around 200 million laying birds in the EU. Our work has
been adopted in EC regulations, and they are pushing all EU member states
to ensure all their producers install aerial perches over slatted
Beneficiaries: Laying birds, welfare organisations, egg producers,
and the general public.
Attribution: Prof. Sparks, Dr. Sandilands (SRUC). Involved
collaboration with Prof. Green at Heriot Watt University acting as a
Reach: Guidelines have been adopted in EU legislation.
There are 320-330 million egg-laying hens in the European Union alone
and, since 2007 and 2012 for hens in extensive and cage systems
respectively, all of these birds now need to have access to aerial
Research from 1993 to 2009 at SRUC (with a team involving Prof. Sparks
(Team Leader, employed 1989-onwards), Drs Sandilands (Behavioural
Scientist, employed 2001-onwards), Moinard (Researcher, employed
2004-onwards), Scott (Researcher, employed 1993-onwards)) initially
focused on identifying optimal perch heights and angles [3.1, 3.2], plus
preferred perch materials [3.3], which influence the safety of a hen's
landing (and likelihood of injury). This was followed by:
- A study to examine small commercial-style systems and how perches
could affect social behaviour and dominancy hierarchies in hens [3.4].
- A study to examine how crowded perches (often found in commercial
systems) can influence the accuracy of hens' landing.
A range of scientific approaches have been used in the work ranging from
training small numbers of birds to move/fly when required between perches
through to the use of pressure load cells to measure forces expended when
hens land on perches. This work combined ethology, ergonomics and
physiology with engineering to provide optimal access to perches, and then
to optimise perch design whilst ensuring that the perch
design/installation did not unduly compromise the ability of stock workers
to move around the facility.
This work has most recently been followed up by examining the
relationship between aerial perches and bone fracture in laying hens [3.5,
3.6]. The contentious view that aerial perches promote keel bone fracture
has led to various interpretations of what is permissible as a perch
within the UK, and has led to a divide among the devolved governments as
to their requirements.
References to the research
3.2) Lambe, N. R., Scott, G. B. and Hitchcock, D. (1997). Behaviour of
laying hens negotiating perches at different heights. Animal Welfare. 6:
29-41. (Copy available on request.)
3.3) Scott, G. B. and MacAngus, G. (2004). The ability of laying hens to
negotiate perches of different materials with clean or dirty surfaces.
Animal Welfare. 13: 361-365. (Copy available on request.)
3.4) Cordiner, L. S. and Savory, C. J. (2001).
Use of perches and nestboxes by laying hens in relation to social status,
based on examination of consistency of ranking orders and frequency of
interaction. Applied Animal Behaviour Science. 71: 305-317. (Copy
available on request.)
3.5) Moinard, C., Rutherford, K. M. D., Haskell, M. J., McCorquodale, C.,
Jones, R. B. and Green, P. R. (2005). Effects of obstructed take-off and
landing perches on the flight accuracy of laying hens. Applied Animal
Behaviour Science. 93: 81-95.
3.6) Sandilands, V., Moinard, C. and Sparks, N. H. C. (2009). Providing
laying hens with perches: fulfilling behavioural needs but causing injury?
British Poultry Science. 50: 395-406. http://dx.doi.org/10.1080/00071660903110844
Details of the impact
The major impact of this work has been to inform EU policy and improve
the welfare of laying hens. The SRUC research was instrumental in
underpinning the decision of policy makers in the EU, and subsequently
administrations in member states, to enshrine in legislation the
requirement that the ca 200 million laying hens housed annually in
extensive systems in Europe have access to perches when in the laying
SRUC research has been used by member states to justify to producers the
need to install aerial perches over slatted surfaces. So for example, in
Scotland the work we have done has enabled Government to be even more
specific in interpreting relevant EU legislation, with the Government
requirement being that hens have access to aerial perches (Welfare of
Farmed Animals (Scotland) Amendment Regulations 2002 (SSI 2002 No. 334))
while continuing to use literature that we have produced in 2007 to guide
producers as to the requirements and benefits of aerial perches. More
recently, producers have attempted to argue against the installation of
perches on the basis that they increase the incidence of bone fractures in
laying hens. Our work has demonstrated that careful design of perches can
address welfare issues and increase productivity without increasing bone
fracture in laying hens.
Further national impact on policy is demonstrated in the Farm Animal
Welfare Council's (now Farm Animal Welfare Committee) (FAWC) opinion paper
on osteoporosis (Dec 2010), which referred to work done by SRUC (on the
association between bone fracture and housing system), and concluded that
`the design and layout of perches can be improved to prevent bone
fracture. If this is achieved, the different interpretations of the
relevant European Directive within Great Britain could be eliminated,
favouring provision of aerial perches.' FAWC advises the UK
Government on animal welfare issues. The work is regularly cited by
welfare bodes and producers alike outside the EU, and remains highly
topical with bodies ranging from the International Egg Commission to New
Zealand's National Animal Welfare Advisory Committee citing the work in
support of requirements to use perches in extensive and, increasingly, in
cage systems (now mandatory within the EU).
SRUC research in this area also has an impact on animal welfare, as
perching is a highly motivated behaviour in hens. The system based on our
research is cited by animal welfare organisations such as Compassion in
World Farming (2012) as an archetypal high welfare system.
Sources to corroborate the impact
5.1) Andrew Voas Veterinary Advisor, Scottish Government http://tinyurl.com/n5whw4j
5.2) FAWC. Opinion on osteoporosis and bone fractures in laying hens.
5.3) CIWF Information Sheet January 2012. Hen welfare in alternative
5.4) EU Directive 1999/74. EC laying down minimum standards for the
protection of laying hens http://tinyurl.com/qal89us
5.5) Defra report 2008. AW0235. A study to compare the health and welfare
of laying hens in different types of enriched cage http://tinyurl.com/nkq9frc
5.6) Defra report 20006. AW0231. The welfare effects of different methods
of depopulation on laying hens http://tinyurl.com/qfcy4ax
5.7) SAC (2007). Perch Designs for Extensive Systems, ISSN 0142 7695 •
ISBN 1 85482 865 7. Technical Note produced for and still used by Scottish