Mule ducks’ (Cairina moschata x Anas platyrhynchos) behavioural reactions to overfeeding show the impact of housing conditions during the ‘foie gras’ production stage

The ‘foie gras’ production sector faces various challenges, among which overfeeding and housing conditions are particularly determinant for the future to meet social expectations. Achieving significant advancements in farm animal welfare requires scientifically validated assessments. To date, determining the real impact of housing conditions during the overfeeding period on mule ducks’ health and welfare appears difficult. The scientific literature still lacks a behavioural assessment methodology to monitor the overfeeding phase in ‘foie gras’ farms. Our study aims to (1) develop and implement an objective measure of behavioural responses in ducks during overfeeding and (2) assess the impact of two housing systems – elevated collective pens (ECP) vs. collective floor pens (CFP) – on ducks’ welfare before and during the overfeeding meal. The developed measure is based on two specific indicators characterising ducks’ reactions – struggling and overall agitation profile – to overfeeding and toward the feeder. In addition to these indicators, data on behaviour and health were also collected. Trials were conducted on commercial farms at two separate sites (hereafter “site A” and “site B”) and repeated with two batches on both sites. Behavioural and health data were recorded for 1226 male mule ducks ( Cairina moschata x Anas platyrhynchos ) 1.5 h before overfeeding and then during overfeeding meals, three times throughout the overfeeding phase. Ducks housed in ECP showed more discomfort behaviours, while ducks housed in CFP expressed more natural behaviours before overfeeding meals. Ducks housed in ECP were also more agitated and struggled more during overfeeding than ducks housed in CFP. Moreover, the thighs (in both sites) and livers (in site A) of ducks housed in CFP were heavier than those of ducks housed in ECP. The results obtained before and during overfeeding meals align and complement each other, providing strong support for the development of new behavioural metrics for mule ducks’ reactivity. Our results also suggest that mule ducks housed in CFP exhibit a more effective coping strategy in response to stressful situations. This strategy is supported by the increased opportunity to explore their environment and engage in species-specific behaviours within this housing system. Finally, the results obtained with the ducks housed in CFP align with the 'one welfare' concept, as CFP enhances not only the well-being of the ducks but also the farmer’s well-being, with the ducks struggling less and being less agitated.