The potential of the transect method for early detection of welfare problems in broiler chickens

Abstract

The potential of the transect method was tested for early detection of welfare problems associated with bird age and genetic line, litter quality, and transect location. On-farm welfare impairment and its consequences on slaughter outcomes were evaluated to test the method's predictive ability. A total of 31 commercial Ross, Cobb, and mixed RC broiler flocks were evaluated at 3, 5, and 6 wk of age. Two observers evaluated 3 transects each, simultaneously and in the same house by detecting welfare indicators including lame, immobile, sick, small, dirty, tail wounds, other wounds (head and back wounds), featherless, terminally ill, and dead birds. Increasing lame, immobile, sick, and terminally ill birds according to bird age (P < 0.001) was detected. Higher incidences of small and sick birds were detected in C and RC (P < 0.001) as compared to R flocks, whereas more dead and tail wounded were observed in RC compared to R and C flocks at week 5 (P < 0.001). Dirty incidence increased as litter quality deteriorated (P < 0.001). A higher incidence of immobile, small, sick, dirty, and dead was registered near house walls (P < 0.001). Differences across observers were detected for lame, immobile, and terminally ill birds (P < 0.001). For the observer by bird age interaction, differences were detected for dirty, tail wounds, and other wounds (P < 0.05). Pearson correlations between welfare indicators at week 3 and those at final weeks of age (P < 0.05) ranged between r values of -0.2 and 0.654 (P < 0.05). Correlations between welfare indicators and slaughter outcomes showed a relationship between flock mortality and dead on arrival, footpad dermatitis, leg problems, and illness (P < 0.05). Litter quality positively correlated with downgrades (P < 0.001). This study showed the potential of transects to detect differences in welfare indicators according to factors that effects were previously reported. It demonstrated the transect potential for detecting and predicting the consequences of welfare impairment on slaughter outcomes. This would make the transect method a useful tool for notifying and rectifying welfare deterioration as early as at 3 wk of age.

Possible improvement of measures within the principle ‘appropriate behaviour’ of the Welfare Quality® boiler assessment protocol

“…Similar findings and hence requirements were found for other welfare indicators, e.g. lameness and sick birds (Ben Sassi et al, 2019). We could not analyse the effect of enrichments on the activity level close to and away from the enrichment, but it is also known that, dependent on the type of enrichment, these may stimulate certain behaviours such as exploration and dustbathing (Kells et al, 2001;Bailie et al, 2013;Bailie and O'Connell, 2014;Bailie et al, 2018b).…”

“…Another important effect is the location in the house, broilers close to walls are less active than those in the centre of the house. It is known that broiler chickens prefer to rest close to the wall, probably because this provides shelter, can be a little more dark, and prevents disturbance by other birds (Buijs et al, 2010;Ben Sassi et al, 2019). To gain a reliable impression of the activity level of a flock, both the areas close to the wall and in the centre use should be included in an assessment.…”

“…Whereas standardisation can be done for factors like time of the day, location in the house and age, the prevention of intraobserver differences (and maybe also for inter-observer differences) might be more difficult even after intensive training. Indeed, a significant observer effect on the prevalence of welfare issues was found when applying the AWIN broiler assessment protocol which contains relatively simple measures of welfare (Ben Sassi et al, 2019). The relatively large observer effects on dustbathing, comfort and foraging behaviour might reflect difficulties in recognising these behaviours, e.g.…”

On-farm broiler chicken welfare assessment using transect sampling reflects environmental inputs and production outcomes

“…Transect sampling is intended for implementation by stakeholders including farmers, veterinarians, animal welfare auditors and advisors to obtain a quick but quantitative snapshot of the current welfare status of the flock. However, previous research indicates the potential for some variation in results from different observers and sampled transects [4, 10, 13], which could mask differences in welfare between flocks. It has not yet been established whether transect sampling can reveal differences in flock welfare according to environmental conditions (e.g.…”

Associations between on-farm welfare measures and slaughterhouse data in commercial flocks of turkey hens (Meleagris gallopavo)

“…There is an increasing demand for a continuous documentation of animal welfare status in commercial meat production industry ( European Commission, 2005 , 2017 ). Recently, transect walks have been found to be a feasible, practical, and validated method for assessing on-farm welfare in broilers ( Marchewka et al., 2013 ; 2019 ; BenSassi et al., 2019 ) and turkeys ( Marchewka et al., 2015 , 2019 ; Ferrante et al., 2019 ). This method is based on line transect methodology, a technique routinely used in ecological studies to estimate animal biodiversity and abundance ( Butler et al., 2007 ).…”