Article

Leg Disorders in Broiler Chickens: Prevalence, Risk Factors and Prevention

School of Veterinary Science, University of Bristol, Langford, Bristol, United Kingdom.
PLoS ONE (Impact Factor: 3.23). 02/2008; 3(2):e1545. DOI: 10.1371/journal.pone.0001545
Source: PubMed

ABSTRACT Broiler (meat) chickens have been subjected to intense genetic selection. In the past 50 years, broiler growth rates have increased by over 300% (from 25 g per day to 100 g per day). There is growing societal concern that many broiler chickens have impaired locomotion or are even unable to walk. Here we present the results of a comprehensive survey of commercial flocks which quantifies the risk factors for poor locomotion in broiler chickens. We assessed the walking ability of 51,000 birds, representing 4.8 million birds within 176 flocks. We also obtained information on approximately 150 different management factors associated with each flock. At a mean age of 40 days, over 27.6% of birds in our study showed poor locomotion and 3.3% were almost unable to walk. The high prevalence of poor locomotion occurred despite culling policies designed to remove severely lame birds from flocks. We show that the primary risk factors associated with impaired locomotion and poor leg health are those specifically associated with rate of growth. Factors significantly associated with high gait score included the age of the bird (older birds), visit (second visit to same flock), bird genotype, not feeding whole wheat, a shorter dark period during the day, higher stocking density at the time of assessment, no use of antibiotic, and the use of intact feed pellets. The welfare implications are profound. Worldwide approximately 2 x 10(10) broilers are reared within similar husbandry systems. We identify a range of management factors that could be altered to reduce leg health problems, but implementation of these changes would be likely to reduce growth rate and production. A debate on the sustainability of current practice in the production of this important food source is required.

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    • "To date, most scientific assessment methods include bird herding and enclosing, as most of the available studies on broiler welfare evaluation are based on scoring particular welfare deficiencies on the individual level (Welfare Quality, 2009). For welfare assessment, bird samples in diverse numbers are taken usually at random locations of the house, and then scored for the chosen set of welfare indicators (Sanotra et al., 2003; Dawkins et al., 2004; Knowles et al., 2008). This commonly used procedure is time consuming because it requires catching, enclosing, and handling birds, but most importantly, it might be stress inducing (Jones, 1992), influencing birds' performance during gait scoring . "
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