Validation and Differentiation of Welfare Indicators in Laying Hens

Lead Research Organisation: University of Bristol
Department Name: Clinical Veterinary Science

Abstract

Valid measures of animal welfare are required to underpin societal and legislative judgements about how to keep and treat animals. Both scientists conducting experiments to assess factors that might influence farm animal welfare (e.g. stocking density or feed type), and assessors visiting farms on behalf of farm assurance programmes, need practical measures of welfare. It is now accepted that, wherever possible, direct measures of animals should be taken (e.g. health, body condition, locomotion, behaviour) rather than simply measures of the environment animals are in (e.g. space allowance, type of bedding) as it is the impact of the environment on the animal that matters for welfare. Because there is no one measure of good or poor welfare, scientists and assessors often take a wide range of measurements. This can be expensive and time-consuming so it would be useful to develop more refined sets of measurements that could be used in a practical context. Of even greater importance, the validity of many currently-used measures is not well-established. In chickens for example, we may measure the plumage condition, keel-bone deformation, prevalence of hair-line fractures, or even walking abnormalities without knowing whether these are perceived as painful or aversive; and there are similar difficulties in identifying indicators of positive welfare. Thus, to identify practical welfare indicators that can be used in a wide range of situations, we need to establish which are associated with the animals' own perceptions and emotions i.e. which indicators really matter to the animals.
In our previous work we validated indicators against hens' own expressed short-term preferences and aversions. This confirmed some useful indicators, threw doubt on the validity of a minority, and resulted in the identification of new indicators. For example, it was not previously known that head-shaking was a reliable indicator of an aversive environment, or that faecal dryness was reliably associated with being in a preferred environment. This information is already being used to improve farm assurance audits. Our original approach works well in the short-term, but cannot be used to validate indicators of long-term welfare, which better reflects lifetime quality of life, because of limitations in how birds express long-term preferences. Our proposed research is thus built on the knowledge that long-term exposure to preferred or non-preferred events or environments can change long-term emotional mood state. Thus, if we cannot validate long-term indicators directly against birds' preferences, we can validate such indicators against the changes in birds' moods that result from long-term exposure to preferred or unpreferred environments.
In the first part of our work we will house chickens in environments that are known to be strongly preferred (positive) or unpreferred (negative)in the short-term. We will assess how long-term exposure to these environments influences mood by performing 'cognitive bias' tests, based on our previous work in other species: animals in a positive mood judge situations differently from animals in a negative mood. We will then use statistical methods to describe welfare indicators (measures of behaviour, physiology, health) that are associated with housing in a positive environment and with measures of positive mood, and to describe welfare indicators associated with housing in a negative environment and measures of negative mood. The second part of the programme will be to expose birds to environments that are positive or negative in different ways (e.g. rich in rewards or sparse in punishments) and to see which indicators are good 'general' indicators of positive or negative experience, and which indicators are 'specific' indicators of particular types of positive or negative experience. These results will produce a new generation of practical indicators for use in refined protocols for assessing laying hen welfare.

Technical Summary

Valid measures of animal welfare are required to underpin judgements about how to keep and treat animals. To identify practical welfare indicators that can be used in a wide range of situations, we need to establish which are associated with the animals' own perceptions and emotions. Previously, we validated sets of short-term welfare indicators for hens against their own expressed preferences and aversions. Although this approach worked well it was difficult to extend it to validate indicators of long-term welfare, due to birds' limitations in expressing long-term preferences. However, long-term exposure to preferred or non-preferred events or environments can change long-term mood state, a major component of lifetime welfare. Thus, although we cannot easily validate long-term indicators directly against birds' preferences, we can validate them against the changes in birds' moods that result from exposure to preferred or unpreferred environments. In this research we will use hens' own expressed preferences and aversions to design events and environments empirically identified as (rather than assumed to be) positive or negative. We will then house hens in these positive or negative environments and evaluate the impact of this on mood, using cognitive bias tests. We will measure a wide range of putative welfare indicators at defined points over a 6 month period and statistically determine indicators associated with long-term positive housing and mood, and indicators associated with long-term negative housing and mood. We will extend the work by designing events and environments that differ in the presence and absence of rewarding and punishing features and establish how this generates different 'types' of positive or negative mood using a wider range of cognitive bias tests. We will statistically determine measures that are good general positive or negative welfare indicators, and identify those that differentiate specific types of positive or negative mood

Planned Impact

The following are potential non-academic beneficiaries of our research:

1. Policy makers. Policy-makers in government and government agencies (e.g. Defra and Animal Health) responsible for producing Codes of Recommendations, inspecting farms and implementing animal welfare law need robust and valid indicators of animal welfare to answer a range of policy questions. An immediate and specific policy need for Defra wrt laying hens is to develop a strategy to facilitate a ban on beak-trimming of laying hens by 2016, in response to a ministerial statement of intent. This requires an overview of the welfare of hens in flocks where beak-trimming has not been conducted. Obvious measures include mortality and plumage damage, but the relevance of mild plumage damage to the birds (how much it matters) is not known. Thus it is very difficult to weigh competing harms and goods in deciding whether overall welfare will be better or worse if beak-trimming is banned.

2. Retailers, assurance scheme providers. The collection of multiple measures for monitoring hen welfare on farms has become accepted practice (eg Welfare Quality, www.welfarequality.net), AssureWel (http://www.soilassociation.org/assurewel). Auditing and assessment protocols should make maximum use of the time and resources available when an assessor visits a farm, whilst providing the most relevant and valid information. This programme of work will help to refine existing protocols by identifying which measures are most valid, providing an insight into potential redundancy in measurement (where different indicators essentially measure the same thing), identifying indicators that provide very little information about what matters to chickens.

3. Animal welfare organisations such as the RSPCA provide schemes such as Freedom Food so that consumers can buy welfare-certified products. Their interest in this research will closely match that of the assurance scheme providers above. In addition, other welfare charities such as Compassion in World Farming, will benefit too by being able to better target their resources to areas where animal welfare really is poor rather than simply perceived to be poor.

4. The public remains greatly interested in many farm animal welfare topics. We have been very actively involved in public engagement activities, giving well-received talks on "Farm Animal Minds" and "Animal Sentience", as well as contributing to programmes such as the BBC Secret Life of Farm Animals (2010) and the One Show (2011) which explored how to measure the welfare of chickens. This information informs the UK public and may guide their decisions about what types of animal products they wish to purchase, at what price. We have standing invitations from some media shows to contact them if we make interesting discoveries about chicken welfare, and it would be our plan to do so as soon as we are sure we have robust results.

5. Chickens. Chickens will benefit if efforts to improve their welfare are most targetted at the things that matter most to them

6. The laying hen industry will benefit from greater agreement and alignment in policies pursued by governments, charities and others.
 
Description It has taken longer than expected to fully analyse the work and produce appropriate papers. Initial outputs have been published (Paul, E.S., Edgar, J.L., Caplen, G., & Nicol, C.J. (2018) Examining affective structure in chickens: Valence, intensity, persistence and generalisation measured using a Conditioned Place Preference test. Applied Animal Behaviour Science 207, 39-48; Paul, E.S. & Mendl, M.T. (2018) Animal emotion: Descriptive and prescriptive definitions and their implications for a comparative perspective. Applied Animal Behaviour Science 205, 202-209). A substantial based on the main Programme 1 of the project was submitted to a peer reviewed journal in autumn 2020 and is currently under review. This paper has a focus on hens' behavioural and physiological indicators associated with long-term (approx. 6 months) residence in preferred and non-preferred housing/husbandry conditions and the relation of these results to cognitive bias. We have termed this a "triangulation approach" to animal welfare. A second paper will cover the influence of stability vs trajectory (up and down-shifts) in housing/husbandry conditions on hens' behaviour and physiology. Further papers are also in preparation based on results from Programme 2 which aimed at further differentiating affective states in hens beyond positive and negative affective valence. One of these, "Using thermography to differentiate affective responses in hens", conducted in collaboration with Ms Helena Telkanranta (university of Helsinki) has been fully coded (data extracted from thermographic videos) and is now ready to be analysed and written. In collaboration with Ms Amanda Deakin and Mr Misha Buob (PhD students at University of Bristol & University of Guelph, respectively), we also developed a Go/Go (High/Low food reward) judgment bias task with laying hens, the first such task to be developed with chickens. These students have now completed their studies and the task they developed is being used as a basis for further research.
Exploitation Route Too early to say
Sectors Agriculture, Food and Drink

 
Description They have informed new guidance for Home Office standards for keeping poultry. They have been used to inform Farmed Bird Review written for Australian government and presentation given to European Parliament on chicken welfare March 2019. They have been used to inform a review completed for the Welsh government on housing systems for laying hens and are also informing participation of Christine Nicol in 2021 EFSA working group on laying hen welfare.
First Year Of Impact 2019
Sector Agriculture, Food and Drink,Government, Democracy and Justice
Impact Types Policy & public services

 
Description Farmed Bird Review for Australian Government
Geographic Reach Australia 
Policy Influence Type Gave evidence to a government review
Impact The farmed bird review was commissioned by the Victorian Department of Economic Development, Jobs, Transport and Resources (DEDJTR) It examines contemporary scientific evidence on the care, management and slaughter practices used in the farming of poultry, game birds and ratites (emus and ostriches). The review was undertaken by the University of Bristol which is world-renowned for its work in farmed bird welfare, and was independently peer-reviewed by Australian and New Zealand animal welfare scientists. The review is being used in consultations about the Australian Draft Australian Animal Welfare Standards and Guidelines for Poultry as part of a national process involving all Australian states and territories.
URL http://agriculture.vic.gov.au/agriculture/animal-health-and-welfare/animal-welfare/farmed-bird-welfa...
 
Description Invited talk on concept of animal welfare and methods of assessment to International Whaling Commission
Geographic Reach Multiple continents/international 
Policy Influence Type Participation in a advisory committee
 
Description Invited talk on use of preference tests to assess chicken welfare to UK Home Office Inspectors
Geographic Reach National 
Policy Influence Type Influenced training of practitioners or researchers
 
Description BBSRC Standard Proposal
Amount £540,000 (GBP)
Funding ID BB/N00860X/1 
Organisation Biotechnology and Biological Sciences Research Council (BBSRC) 
Sector Public
Country United Kingdom
Start 05/2016 
End 04/2019
 
Description International Partnering Awards
Amount £32,000 (GBP)
Funding ID BB/N021959/1 
Organisation Biotechnology and Biological Sciences Research Council (BBSRC) 
Sector Public
Country United Kingdom
Start  
 
Description MLA Donor Company Project
Amount $4,876,136 (AUD)
Funding ID Objective, robust, real-time animal welfare measures for the Australian red meat industry. P.PSH.0819 
Organisation Meat & Livestock Australia 
Sector Charity/Non Profit
Country Australia
Start 01/2017 
End 12/2021
 
Description No specific scheme
Amount £131,500 (GBP)
Organisation Griffiths Family Farms 
Sector Private
Country United Kingdom
Start 02/2019 
End 01/2021
 
Description Travel award for Anna Davies
Amount £600 (GBP)
Funding ID Arthur Hosier Trust award 
Organisation University of Bristol 
Sector Academic/University
Country United Kingdom
Start 07/2016 
End 07/2016
 
Title High Definition Oscillometry measures blood pressure and pulse rate in chickens 
Description We have evaluated,calibrated and developed protocols ot use a High Definition Oscillometry blood pressure monitor (MD Pro) for non-invasive measurement of pulse rate, systolic, diastolic and mean arterial blood pressure in chickens. We have shown that the monitor is highly sensitive and offers good repeatability between measurements provided bird handling procedures are standardised. This has provided us with a novel methodology for monitoring cardiac activity in chickens that have been long-term housed in preferred or non-preferred environmental conditions, as a potential indicator of chronic stress. 
Type Of Material Physiological assessment or outcome measure 
Provided To Others? No  
Impact Too early to evaluate 
 
Title Refined cognitive bias tasks for laying hens 
Description We developed a go/go reward-reward cognitive bias task for use with chickens. This makes use of hens' judgements about the predictive reward value of ambiguous conditioned stimuli to assess their background affective state. This kind of task has not been used before with chickens. We also extended and refined a go/no-go reward-punishment task first designed as part of a previous project (Deakin et al., 2016). 
Type Of Material Model of mechanisms or symptoms - non-mammalian in vivo 
Provided To Others? No  
Impact Too early to evaluate 
 
Title Thermography in laying hens 
Description We have developed our work on non-invasive recording of skin temperature in chickens by using new infra-red cameras with finer and faster resolution that previous models, allowing assessments of intra- and individual variation, and setting guidelines for best practice. 
Type Of Material Physiological assessment or outcome measure 
Year Produced 2017 
Provided To Others? Yes  
Impact It has allowed new, ongoing studies 
 
Description Chicken brain analysis by University of Newcastle 
Organisation Newcastle University
Country United Kingdom 
Sector Academic/University 
PI Contribution We will supply the brains of chickens that have been housed in our long-term differentiated conditions.
Collaborator Contribution The partners will analyse the brains to examine links between chronic stress and neurogenesis
Impact Paper submitted for conference: UFAW International Symposium (2017) on Measuring Animal Welfare. Armstrong, E., Gualtieri, F., Longmoore, G.K., Browne, W., Caplen, G., Davies, A., Held, S., Kelland, I., Mendl, M., Nicol, C., Paul, E., D'Eath, R.B., Sandilands, V., Boswell, T and Smulders, T (2017) The caudal pole of the avian hippocampus is sensitive to chronic stress.
Start Year 2016
 
Description Collaboration with Bucknell University 
Organisation Bucknell University
Country United States 
Sector Academic/University 
PI Contribution We have supplied DNA taken from chickens in the long-term housing treatments of our main study
Collaborator Contribution Our partners are analysing the DNA to look for differences in telomere length between treatments.
Impact Collaboration only started in 2017, results not yet available
Start Year 2017
 
Description Collaboration with Friedrich-Loeffler-Institut 
Organisation Friedrich Loeffler Institute
Country Germany 
Sector Academic/University 
PI Contribution I provided input on experimental design and methodology, based on ongoing BBSRC funded research on best methodologies to assess laying hen welfare
Collaborator Contribution They conducted the relevant experiments on motivation of laying hens for elevated and graspable (perch-type) roosting sites.
Impact Joint conference paper. Collaboration started after meeting at a European Food Safety Authority expert panel on perching provision for hens. There are potential policy implications of this work as it develops further.
Start Year 2015
 
Description Collaboration with NMBU, Norway 
Organisation Norwegian University of Life Sciences (NMBU)
Country Norway 
Sector Academic/University 
PI Contribution We provided advice on validated welfare indicators for a Norwegian trial of laying hen rearing methods
Collaborator Contribution They ran the study of laying hen rearing methods on a commercial farm in Norway
Impact A paper in PLoSOne
Start Year 2014
 
Description Collaboration with University of Helsinki 
Organisation University of Helsinki
Department Department of Geosciences and Geography
Country Finland 
Sector Academic/University 
PI Contribution We have provided hens and expertise in specific welfare assessment methods (e.g. infrared thermography) to enable add-on studies to validate welfare indicators.
Collaborator Contribution Researcher Helena Telkanranta has visited and is conducting two studies on thermography of domestic hens: mapping variation in temperature of comb, eyes, cheek and nostrils.
Impact Studies in progress
Start Year 2016
 
Description Collaboration with the Hebrew University, Rehovot, Israel 
Organisation Hebrew University of Jerusalem
Department Koret School of Veterinary Medicine
Country Israel 
Sector Academic/University 
PI Contribution Contribution is to advise and supervise PhD project on behavioural priorities in dairy cows, using methodologies that we continue to develop as part of our BBSRC funded work.
Collaborator Contribution The partners have conducted extensive empirical work on dairy cows in Israel
Impact Five peer-reviewed papers and a number of conference proceedings.
Start Year 2018
 
Description BBC Radio 4 series 
Form Of Engagement Activity A broadcast e.g. TV/radio/film/podcast (other than news/press)
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact BBC Radio 4, four-part series on animal ethics and animal welfare, written and presented by Professor Christine Nicol, produced by Mary Colwell.
Year(s) Of Engagement Activity 2015
URL http://www.bbc.co.uk/programmes/b06s2w7b
 
Description Contribution to Channel 4 TV documentary 
Form Of Engagement Activity A broadcast e.g. TV/radio/film/podcast (other than news/press)
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Media (as a channel to the public)
Results and Impact We trained 4 hens to demonstrate the sorts of techniques used to establish behavioural priorities - latency to move down a runway, weight pushed to access a resource, non-invasive measures of physiological arousal. This formed part of a Channel 4 documentary on laying hen welfare as part of the series Food Unwrapped
Year(s) Of Engagement Activity 2016
 
Description Contribution to French TV documentary 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact Interviewed by Franz-Olivier Giesbert at School of Veterinary Science for French documentary on animal welfare. Broad range of questions about how animal welfare can be assessed.
Programme aired on the French TV Channel "France 3" on November, Monday 23, at 8:50pm.

TV documentary makers report high audience interest
Year(s) Of Engagement Activity 2015
 
Description Contribution to French documentary on animal cognition and welfare 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact Documentary made by What's Up Films
Year(s) Of Engagement Activity 2016
 
Description Contribution to regional evening news BBC Points West 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact Interviewed about how to assess chicken welfare
Year(s) Of Engagement Activity 2016
 
Description Public Lecture 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact University of Plymouth/ UFAW Public Lecture on topic of animal welfare science
Year(s) Of Engagement Activity 2018
URL https://www.plymouth.ac.uk/schools/school-of-biological-and-marine-sciences/the-annual-plymouth-anim...
 
Description Virtual lecture at University of Guelph 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Postgraduate students
Results and Impact Seminar given as part of the Campbell Centre for the study of animal welfare series.
Year(s) Of Engagement Activity 2021
URL https://www.uoguelph.ca/ccsaw/events/archive
 
Description collaborative meeting with staff from Bristol zoo 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Other academic audiences (collaborators, peers etc.)
Results and Impact Discussion and plans for future inter-disciplinary events

Updated zoo staff on current research on animal cognition
Year(s) Of Engagement Activity 2014