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Welfare Assessment on Broiler Farms: Transect Walks versus Individual Scoring

28 October 2013

Designers of on-farm welfare assessment protocols are set to benefit from a new study from Spain, which provides new insights into constraints and advantages of different farm assessment methods for broilers.

Current scientific approaches to welfare assessment in broilers are based on individual sampling that can be time-consuming under field conditions, according to J. Marchewka of Neiker-Tecnalia, Arkaute Agrifood Campus in Vitoria-Gasteiz, Spain, and co-authors there and at the University of Milan in Italy and IKERBASQUE, Basque Foundation for Science in Bilbao, Spain.

On the other hand, they explain in a paper in Poultry Science, farmers conduct routine checks based on walks through the house to screen birds’ health condition.

The researchers adapted the walks through following line transect methodology used in wildlife studies to explore their feasibility as a welfare assessment tool.

The aim of their study was to compare broiler welfare assessed by individual sampling and transect walks. They evaluated six identically managed flocks.

For individual sampling, they collected measures on 150 birds, including weight, breast dirtiness, hock and footpad dermatitis, lameness and immobility.

Transect observations were conducted by slowly walking on randomised paths within each house recording: immobility, lameness, back dirtiness, sickness, agony and dead.

Transect walks allowed detection of small variations (P<0.003) in the prevalence of most welfare indicators considered with consistency in interobserver reliability (P≥0.05). In addition, assessments across transects were highly consistent (P≥0.05).

Individual sampling was also sensitive to differences across houses (P<0.01) with the exception of immobility (P=0.783).

No differences were found across sampling locations (P≥0.05).

However, both methods differed greatly in the frequency of the incidence of the parameters considered. For example, immobility varied from 0.2 ± 0.02 per cent for transect walks to 4.0±2.3 per cent for individual sampling, whereas lameness varied between 0.8±0.07 per cent and 24.2±4.7 per cent for transect and samplings, respectively.

It is possible that the transect approach may have overlooked walking deficiencies because a large number of birds were scored, although if this was the case, the consistency obtained in the scoring across observers and transects would be surprising, Marchewka and co-authors commented.

Differences may also be related to possibly biased individual sampling procedures, where less mobile and passive individuals may be more likely to be caught.

Furthermore, the procedure may cause fatigue and fear reactions reducing mobility.

The researchers conclude that the study provides new insights into constraints and advantages of broiler on-farm assessment methods, which should be considered for designing on-farm welfare assessment protocols.


Marchewka J., T.T.N. Watanabe, V. Ferrante and I. Estevez. 2013. Welfare assessment in broiler farms: Transect walks versus individual scoring. Poult. Sci. 92(10):2588-2599. doi: 10.3382/ps.2013-03229

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October 2013

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