On-farm comparison of the Welfare Quality(r) resource-based versus an animal-based measure of thirst in broiler chickens

In the Welfare Quality® broiler welfare assessment protocol the absence of thirst is measured by the percentage compliance with a recommended number of birds per drinker. The reliability and validity of this resource-based measure has not been tested, however, and there is growing consensus that animal-based measures are preferred as they allow a more direct assessment of animal welfare. We compared the Welfare Quality® measure of thirst with a novel animal-based test on 10 Belgian and 10 Brazilian broiler farms. Per flock 4 groups of 5 chickens from 4 locations (2 near walls, 2 central) were enclosed and the amount of water consumed from an unfamiliar open drinker during 90 min was measured. The mixed model indicated that water consumption in the first test was higher in Brazil than Belgium (P<0.001), but was not affected by location. The Welfare Quality® thirst scores were not correlated with the water consumption of Belgian (r=-0.10, P=0.55) or Brazilian (r=0.20, P=0.23) birds. Furthermore, the drinker ratio was not associated with the water consumption test outcome (P>0.05). These results cast doubts about the validity of the thirst-measure used in Welfare Quality®. An animal-based measure based on voluntary water consumption from an open drinker could be a superior alternative provided further testing of sensitivity and confounding factors.