Review: Fitness for transport assessment for end-of-lay hens

Transportation, together with catching and crating, can be extremely stressful procedures. Hence, planning and correctly assessing the fitness of the birds to withstand the journey are essential to maintain an adequate level of welfare during transportation. End-of-lay hens are at particular risk of experiencing negative welfare consequences during catching and transportation due to their compromised physiological state (weakened bones, metabolic exhaustion and poor feather cover) and long travel distances to the few slaughterhouses available for the slaughtering of this type of birds. Before loading, inspectors and personnel need to know which fitness characteristics to inspect in order to determine whether the birds are fit or not to cope with the transport challenges (e.g. fasting, trailer movements, noise, vibrations, social disruption or thermal stress). However, European regulations do not define the terms “fit” or “unfit” for transport and there are no reviews nor guidelines that discuss the relevancy and assessment methods for on-farm indicators to assess the fitness for transport for end-of-lay hens. The present document discusses the definition of fitness for transport and reviews the animal-based indicators to be considered for the assessment of fitness for transport of end-of-lay hens, based on the literature and opinion of the authors. The selected indicators are: presence of severe open wounds, prolapses, severe lameness, broken bones (legs, wings) and dislocations, keel bone damage, emaciation and cachexia, dehydration, poor feather cover, wet plumage and evident signs of illness. For each indicator, a brief definition, the methods available for their assessment, the criteria used to decide the fitness for transport of birds and the knowledge gaps encountered are included. It has been found that clear and specific definitions for laying hens are missing for some of the indicators selected, as the terms used are general, have been established for other species, or are imprecise. Regarding the methods available, although some of the selected indicators have multiple scoring methods validated for laying hens on farm, there is no scoring method for assessing them in terms of fitness for transport. In other cases, there are no specific methods developed for laying hens at all. Even if assessment methods are available, in some cases there is a lack of thresholds to differentiate whether the animals are fit or unfit for the journey. Finally, some of the existing methods for the assessment of certain indicators rely on palpation or visual inspection, meaning that handling of the animals is needed. This can be time consuming, and an assessment strategy should be discussed. In conclusion, a substantial quantity of gaps of knowledge have been found. They should be addressed before practical guidelines to assess fitness for transport of end-of-lay hens can be produced.