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


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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    • "These problems were estimated to cause economic losses of 80 to 120 million dollars annually in the United States (Sullivan, 1994). To our knowledge, no recent estimations were published; however, in a survey of commercial broiler flocks, Knowles et al. (2008) found that more than 27.6% of the birds suffered from poor locomotion, and 3.3% were almost unable to walk. Such impaired walking ability is expected to reduce production due to reduced feed consumption, increased frequency of downgrades and condemnations, and elevated mortality (Sullivan, 1994). "
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    ABSTRACT: The objective of this study was to examine the effect of in ovo feeding (IOF) with inorganic minerals or organic minerals and vitamin D3 on bone properties and mineral consumption. Eggs were incubated and divided into 4 groups: IOF with organic minerals, phosphate, and vitamin D3 (IOF-OMD); IOF with inorganic minerals and phosphate (IOF-IM); sham; and non-treated controls (NTC). IOF was performed on embryonic day (E) 17; tibiae and yolk samples were taken on E19 and E21. Post-hatch, only chicks from the IOF-OMD, sham, and NTC were raised, and tibiae were taken on d 10 and 38. Yolk mineral content was examined by inductively coupled plasma spectroscopy. Tibiae were tested for their whole-bone mechanical properties, and mid-diaphysis bone sections were indented in a micro-indenter to determine bone material stiffness (Young's modulus). Micro-computed tomography (μCT) was used to examine cortical and trabecular bone structure. Ash content analysis was used to examine bone mineralization. A latency-to-lie (LTL) test was used to measure standing ability of the d 38 broilers. The results showed that embryos from both IOF-OMD and IOF-IM treatments had elevated Cu, Mn, and Zn amounts in the yolk on E19 and E21 and consumed more of these minerals (between E19 and E21) in comparison to the sham and NTC. On E21, these hatchlings had higher whole-bone stiffness in comparison to the NTC. On d 38, the IOF-OMD had higher ash content, elevated whole-bone stiffness, and elevated Young's modulus (in males) in comparison to the sham and NTC; however, no differences in standing ability were found. Very few structural differences were seen during the whole experiment. This study demonstrates that mineral supplementation by in ovo feeding is sufficient to induce higher mineral consumption from the yolk, regardless of its chemical form or the presence of vitamin D3. Additionally, IOF with organic minerals and vitamin D3 can increase bone ash content, as well as stiffness of the whole bone and bone material in the mature broiler, but does not lead to longer LTL.
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    • "Similarly, when birds with gait score higher than one are detected, the Certified Humane Ò (2009) recommends companies to establish corrective actions to address possible causes of lameness (requirement 5A H7). Since gait score higher than one have been reported in an average prevalence of 71.2 % in fast growing chicken broilers (Knowles et al. 2008), choosing a more resistant breed may be one of the most effective actions to be taken by companies to reduce lameness in commercial flocks. It is in agreement with CIWF (2012) recommendation of prohibition of fast growing lines in certification schemes to improve animal welfare. "
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    ABSTRACT: The intensification of farm animal welfare debate has led to an increasing number of certification schemes covering this issue; however, there are concerns about the contribution of these schemes in improving welfare. The aims of this study were to identify certification schemes for broiler chicken welfare at farm level in Brazil, to investigate the extent of nutritional, environmental, health and behavioral indicators within the schemes and to analyze the content of scheme and the capacity to promote continuous improvement on certified farms. GLOBALG.A.P.® and Certified Humane® were the only schemes observed, corresponding to 2.1 % of broiler chicken farms in Brazil. Environmental and health indicators were in greater number, and the requirements classified as behavioral indicator were commonly related to the resolution of low levels of animal welfare. Both schemes were in accordance with the European Food Safety Authority recommendations for farmer training, birds and buildings inspection, temperature control, air and litter quality, stocking density and lighting. The selection of breeds and the use of animal-based indicators needs to be improved, as well the inclusion animal welfare objectives and management review as part of continuous improvement. Welfare certification is a potential market to be developed in Brazil. Overall, assessed schemes may potentially enhance animal welfare at farm level by including new concepts and practices. It is desirable to increase the number of certified farms in Brazil and that certification schemes be critically analyzed on a regular basis regarding their content to meet new demands and to include updates from scientific research.
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    • "Joint lesions/Lameness: some degree of lameness can be seen in many flocks, with a proportion of birds progressing to severe lameness. Joint pathologies may be detected at slaughter, but lameness scoring of live birds on-farm is not yet a common feature of assessment as it is potentially time consuming (Kestin et al., 1992; Sørensen et al., 2000; Sanotra et al., 2003; Bokkers and Koene, 2004; Kristensen et al., 2006; Knowles et al., 2008). Hock burn: lesions on the tibiotarsal skin surface caused predominantly by contact with litter that is in poor condition (Haslam et al., 2007; Meluzzi et al., 2008a). "
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