Assessing the welfare of extensively managed sheep: an evaluation of animal-based welfare indicators
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Date
29/11/2016Author
Richmond, Susan Emily
Metadata
Abstract
The increased public interest in the welfare of animals used in food production has
led to the emergence of welfare assessment schemes for a range of livestock species.
There are currently over 100 million sheep in the EU which are primarily bred for
milk, meat and wool production and the majority of these animals are managed
extensively. The general perception of sheep in extensive systems living “natural
lives” with few welfare compromises, along with the practical challenges of
adequately assessing their welfare, has caused them to be largely ignored in
comparison to other species. It was only relatively recently that the lack of animalbased
welfare assessments for extensively kept small ruminants was recognised.
Thus, the aim of this project was to evaluate potential animal-based welfare
indicators for use during on-farm welfare assessments of extensively managed
sheep. The current project used the Welfare Quality® 4 principles and 12 criteria as
a foundation for selecting indicators for the assessment of extensively managed
sheep. Following a comprehensive review of the scientific literature and a meeting
attended by experts from across the EU, 16 indicators were selected for evaluation.
Each principle and criteria were covered by at least one of these 16 indicators
ensuring the main aspects of sheep welfare were addressed. The indicators selected
for investigation could either be applied without handling or gathering the animals
during an `Assessment in the Field´, or during a more thorough hands-on
`Assessment at Gather´. The reliability, feasibility and validity of some indicators
(e.g. body condition scoring) are already established. However for others (e.g.
Qualitative Behavioural Assessment approach), at least one of these criteria required
further investigation before the indicator could be accepted. The reliability of
selected measures was evaluated by assessing their repeatability and inter-observer
agreement. Face validity was assumed for the indicators selected during the expert meeting, and further cross validation was performed when appropriate using
additional information collected on the animal’s physical health status. During the
Assessments at Gather blood samples were collected for the assessment of metabolic
profiles, and faecal samples provided gastro-intestinal parasite counts.
The Assessments at Gather were performed on the same 100-135 Scottish Blackface
ewes across a two year period (2011-2013) on a Scottish hill farm. The Assessments
at Gather occurred five times a year coinciding with key points in the ewes’
reproductive cycle: pre-mating, mid-pregnancy, late pregnancy, mid lactation and
weaning. During the assessments data were collected on the ewe’s body condition,
coat cleanliness, faecal soiling score, respiratory conditions, anaemia, lameness and
udder condition (udders assessed during lactation only). Current stage in the
reproductive cycle and seasonality were found to have significant impacts upon the
long-term reliability of the following measures: body condition score, tooth loss,
nasal discharge and anaemia scores (P<0.001) with variation both within, and
between years. On commercial farms older and less productive ewes tend to be
removed from the flock once a year prior to mating. Of the indicators applied to the
ewes during the Assessments at Gathers, tooth loss and body condition score were
the best predictors for the ewe’s exclusion from the flock, predicting the future
removal of a ewe from the flock 12 months in advance of the shepherd’s decision.
For the Assessments in the Field, indicators which did not necessitate close contact
were required. A whole-animal method (Qualitative Behavioural Assessment (QBA)
was therefore particularly useful as it can be performed with minimal disturbance.
Rather than quantitatively scoring the behaviour patterns of an animal the assessor
focusses on how the animal interacts with their environment. This information is
translated in to qualitative descriptors such as “calm” or “agitated”. Good interobserver
reliability was found when three observers assessed 49 individual ewes on two occasions (W=0.77, P<0.001). When QBA was applied 13 times to 50 individual
ewes over a six-month time period (spanning late pregnancy to post-weaning) four
meaningful Principal Components were identified; the first two accounted for more
than half of the explained variation between sheep. The two main components were
‘General Mood’ (PC1), describing the overall affective state of the ewe, and ‘Arousal’
(PC2) reflecting energy levels. General Mood scores significantly increased in the
post-lambing period compared to pre-lambing observations, and significantly
increased again post-weaning (P<0.001). Ewes were significantly experiencing
significantly higher Arousal in post-lambing and post-weaning conditions compared
to pre-lambing (P<0.001), but there was no difference between post-lambing and
post-weaning. During the Assessments in the Field data were also collected on: the
ewe’s response to human approach, a surprise test, the ewe’s social group size, group
demographics and behavioural synchrony. Ewes with lower mood scores tended to
have larger distances between them and other ewes (P=0.023). The distance to
which a human could approach before the ewe fled was significantly related to
Arousal (P=0.05), as ewes in a higher energy state fled from the approaching human
sooner than those who were in lower Arousal states. Ewes in social groups with
higher numbers of ewe and lamb vocalisations tended to have lower General Mood
scores (P=0.014), and lower Arousal scores (P<0.001) than those in smaller groups.
Indicators which met the conditions of feasibility, reliability and validity (for
example, those reported above) proved to be suitable for use when assessing the
welfare of extensively managed sheep. The effect of time on the reliability of the
indicators applied during the assessments have important implications for
understanding temporary fluctuations in the animal’s welfare caused by either
internal (reproductive state) or external (environmental) factors. These fluctuations
may not be representative of a farm’s overall welfare levels in the long term and therefore further careful consideration of the most appropriate time to apply the
selected indicators is required.