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

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.