Abstract
Health status, feed conversion ratio, and mortality are long known broiler chicken production indicators. However, further parameters are required by today's demanding meat markets, as these indicators are not sufficiently accurate to determine flock overall welfare. Morphological asymmetry has been pointed as an alternative welfare indicator as it reflects the ability of the bird to cope with the challenges that rearing conditions may impose. This study aimed at evaluating the possibility of using morphological asymmetry as a welfare indicator. Broilers from 28 to 42 days of age were used in the trial. Birds were randomly selected in a commercial poultry farm and transported to the laboratory. They walked over the force measurement platform in order to determined their feet force as a percentage of body weight. The following body parts of the live birds were measured by two different operators using a digital caliper: tarsometatarsus length, outertoe length, midtoe length, and backtoe length. In the corresponding carcasses, the following traits were measured: wattle width, eye length, and first secondary feather length. Data were submitted to statistical analyses and no correlation was found between specific feet trait measurements and walking ability. Considering the time budget involved in measuring morphological asymmetry, this procedure did not appear to be a practically feasible welfare indicator.
Highlights
The latest focus of animal welfare research is to provide evidence on how certain genetic and rearing components may affect animals' expressive response and biological functioning (Dawkins et al, 2004; Broom, 2006)
Morphological asymmetry (MA) has been pointed as a potential animal welfare indicator as it reflects the ability of an individual to cope with the challenges that may affect its growth during a certain period of life (Tuyttens, 2003; Broom, 2006; Knierim, 2007)
Asymmetry is defined as random direct deviations from perfect growth symmetry that is generally expected in certain body parts when there was a successful control of the morphological development, and it is a result of both genetic factors and environmental conditions
Summary
The latest focus of animal welfare research is to provide evidence on how certain genetic and rearing components may affect animals' expressive response and biological functioning (Dawkins et al, 2004; Broom, 2006). The correct deduction of animal “affective” status based on such indicators may improve with the number of observed factors (behaviors, reactions, environment, etc.), and must involve multiple elements that should be combined in order to provide an accurate welfare prediction (Tuyttens, 2003). Morphological asymmetry (MA) has been pointed as a potential animal welfare indicator as it reflects the ability of an individual to cope with the challenges that may affect its growth during a certain period of life (Tuyttens, 2003; Broom, 2006; Knierim, 2007). Asymmetry is defined as random direct deviations from perfect growth symmetry that is generally expected in certain body parts when there was a successful control of the morphological development, and it is a result of both genetic factors and environmental conditions
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