Advancing animal welfare science:welfare assessment and early life programming

Lead Research Organisation: Royal Veterinary College
Department Name: Clinical Sciences and Services


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Description A new method was developed to assess the extent to which hens grouped together (cluster). This method has been named
'the cluster score method'. High cluster scores mean that hens group together and are often found together in the same
location, whereas, low cluster scores mean that hens spend most of their time apart. We investigated how these cluster
scores changed in different types of environments. In the first study we looked at whether cluster scores altered when hens
were housed in environments with lots of resources (perches, nest boxes and peat, plus feeders and drinkers) compared to
environments without these resources (just feeders and drinkers). Clustering appeared to be mainly due to hens grouping around the same resources and cluster scores were reduced (hens grouped together less) in the environments without extra resources. Hens were given a choice between two environments and they preferentially selected the environment with extra resources, where their cluster scores were lowest.

In a second study cluster scores were highest (hens grouped together more) in environments containing a "risk-cue"
representing a perceived threat. This threat was a robotic predator which was lowered into the pen at random time points. It is likely that the hens grouped together in response to the threat because predator detection can increase in larger groups. This is because more eyes are keeping watch and if an individual sees a threat the others can be alerted. In addition, the odds of an individual hen being attacked are lower when they are in groups then when they are alone. We then
investigated whether hens' cluster scores were related to previously established measures of welfare for example skin and feather condition. Again, in this study hens' selected environments where their cluster scores were lower (environments without a "risk-cue"). In addition hens which had very high cluster scores had increased feather damage to their tail tips. More research is needed although; the cluster score may be a potential new indicator of welfare.

Broilers, as opposed to egg-layers, have been extensively selected for fast post-hatch growth rates and high yield of breast meat to meet consumer demand. This was achieved with little concomitant increase in limb muscle growth. As a result, broiler chickens suffer from leg deformities and lameness which affect their welfare. We examined whether manipulating egg incubation conditions would improve leg muscle and bone development thereby improving posture and welfare posthatch.

We subjected eggs to either thermal (high/low) or mechanical manipulation over 4 days early in development and
monitored birds from early incubation to commercial slaughter age (D42). All manipulations had an influence on the
prehatch development of muscle and/or bone in the chicks. Reducing egg incubation temperature by 1 degree celsius
resulted in slower-growing birds (till D5) that caught up (and exceeded) the control weight by D25 (in line with increased
feeding). Birds used a shorter stride length at a given speed, indicating a higher frequency of leg movement. Gait score
was higher (i.e. worse than controls) and birds could stand for a shorter time in a fixed position. Male thigh mass was lower
at slaughter. Increasing egg movement during incubation resulted in faster-growing birds which walked faster using larger stride lengths at a given velocity. Birds could stand in a fixed position for longer and the incidence of leg bone rotation was lowered (trend for lower gait score). Improving walking ability and postural stability through non-invasive method such as incubation temperature and egg movement would prove extremely beneficial to the poultry industry and may pave the way for new advances in egg incubation technology.
Exploitation Route The results can be used to inform in the first instance further research into improved welfare management of broiler chickens.
Sectors Agriculture, Food and Drink

Description It is too early to consider the wider impact of the research. At this stage the outputs are restricted to new methods for assessing behavioural clustering of broilers. There also have been several publications that will inform other research
Title Broiler movement data 
Description Experiments for project 1.1 have generated substantial datasets which could be used for future research or student projects. These include lots of movement data and behaviour measured on a continuous scale. 
Type Of Material Database/Collection of data 
Provided To Others? No  
Impact The data will allow further analyses of broiler movements within the context of the experimental setup used in this project. 
Title Statistical algorithm for testing group clsutering 
Description A new method of analysing group clustering termed 'the cluster score method' has been developed by Dr. Lisa Collins. 
Type Of Material Data analysis technique 
Provided To Others? No  
Impact This has been utilised in several publications and preliminary research suggests this could be a useful non-invasive measure of welfare.