Measuring thirst in broiler chickens
Freedom from thirst has been long considered of paramount importance for animal welfare, however a feasible and sensitive animal-based indicator to assess thirst, on-farm or at-slaughter, is not available. In this study, voluntary water consumption over time was investigated and validated
as a non-invasive behavioural parameter for assessing thirst in broiler chickens. Thirty-two groups of four broilers were used in this study and the effect of three factors on water consumption from a test drinker was investigated: duration of water deprivation (0, 6, 12, or 24 h); familiarity
with the test drinker, and age (35 or 37 days). Water consumption was measured after 30, 60, 90 and 120 min following the deprivation period. Water consumption increased with the length of the deprivation period and was greater in birds that had been habituated to the test drinker. The effect
of familiarity was smaller for 24-h deprived groups compared to 6- and 12-h deprived groups. When birds were habituated to the drinker, they started to drink sooner than when the drinker was new. These findings illustrate the potential of simple, animal-based measures, such as water consumption
over time to assess thirst in chickens and this behavioural test may form the basis of an on-farm test that could be included in integrated animal welfare assessment schemes.