Validation and Differentiation of Welfare Indicators in Laying Hens

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.

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

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.