Potential risk factors associated with contact dermatitis, lameness, negative emotional state, and fear of humans in broiler chicken flocks

Abstract

The objectives of this study were to 1) identify determinants of poor welfare in commercial broiler chicken flocks by studying the associations between selected resource-based measures (RBM, potential risk factors), such as litter quality and dark period, and animal-based welfare indicators (ABM), such as foot pad dermatitis and lameness, and 2) establish the breadth of effect of a risk factor by determining the range of animal welfare indicators associated with each of the risk factors (i.e., the number of ABM related to a specific RBM). Eighty-nine broiler flocks were inspected in 4 European countries (France, Italy, the United Kingdom, and the Netherlands) in a cross-sectional study. The ABM were contact dermatitis (measured using scores of foot-pad dermatitis and hock burn, respectively), lameness (measured as gait score), fear of humans (measured by the avoidance distance test and the touch test), and negative emotional state (measured using qualitative behavior assessment, QBA). In a first step, risk factors were identified by building a multiple linear regression model for each ABM. Litter quality was identified as a risk factor for contact dermatitis. Length of dark period at 3 wk old (DARK3) was a risk factor for the touch test result. DARK3 and flock age were risk factors for lameness, and the number of different stockmen and DARK3 were risk factors for QBA results. Next, the ABM were grouped according to risk factor and counted. Then, in a second step, associations between the ABM were investigated using common factor analysis. The breadth of a risk factor's effect was judged by combining the number (count) of ABM related to this factor and the strength of association between these ABM. Flock age and DARK3 appeared to affect several weakly correlated ABM, thus indicating a broad range of effects. Our findings suggest that manipulation of the predominant risk factors identified in this study (DARK3, litter quality, and slaughter age) could generate improvements in the related ABM and thereby enhance the birds' overall welfare status.

Sensitivity of the Welfare Quality® broiler chicken protocol to differences between intensively reared indoor flocks: which factors explain overall classification?

“…However, the early date of some of our farm visits (up to 10 days before slaughter) and our modest sample size may have decreased our chances of finding associations. We did confirm the association between litter quality and dermatitis reported by Bassler et al (2013). Models on the criterion level allowed a reduction in assessment time of~1 h, by making the 'dust', 'breast blister' and 'lameness' measure redundant.…”

“…Previous studies have suggested a correlation between dermatitis and plumage cleanliness (Arnould and Colin, 2009;De Jong et al, 2015) or litter quality (Bassler et al, 2013), but these studies differ considering a possible correlation between dermatitis and lameness. Thus, the stability of such correlations still needs confirmation.…”

Pathomorphological investigations on the prevalence of contact dermatitis lesions in broiler chickens

“…Among the common risk factors, we are inclined to add fast-growing broiler flocks, the age at which they are slaughtered, etc. (de Jong et al 2012;Bassler et al 2013;Tullo et al 2017). With regards to the findings of Greene et al (1985), namely that breast and tarsometatarsal lesions were of economic significance, we believe that PPD, leading to a worsened welfare of the flock, is also related to a loss of produce for poultry farmers.…”

Genetic selection of broilers and welfare consequences: a review

“…The mean prevalence of broilers displaying a gait score of 3 or above has previously been reported to be between 15 and 55% (Kestin et al 1992;Sanotra et al 2001;Knowles et al 2008). More recently, studies conducted across multiple flocks, farms and countries have reported the prevalence of birds with a moderate to severe gait impairment (gait score 3 or above) to be between 5.5 and 48.8% (Bassler et al 2013;Tahamtani, Hinrichsen and Riber 2018;Kittelsen et al 2017;Granquist et al 2019).…”