Exploration of new Emotional Biomarkers in Hens: blushing and Immunoglobulin A - RED

Context and challenges

Experiencing pleasant events, and their repetition, appears to be an essential lever in order to induce a state of sustainable well-being over the long term. However, because of their subtlety, positive emotions remain much less studied than those which are negative. During the past twenty years, one of the main challenges in this area has been a capability to identify non-invasive behavioural or physiological markers of positive emotions in farmed livestock. This lack of relevant markers is particularly pronounced in birds.

Objectives

The objective of the RED project will be to explore two new and non-invasive markers of emotions in domestic fowl: facial expressions and secreted levels of immunoglobulin A. The first stage of the project will consist in observing small groups of farm bred hens under semi-natural conditions in order to determine whether changes to the position of facial feathers or the colour of the skin on their cheeks and appendages vary as a function of the activities in which they are engaged. This will clarify whether facial expressions might be specific to the affective valence and/or state of excitation they are experiencing. The second stage of the project will be carried out under experimental conditions on small groups of free-range hens to determine whether the combined use of facial expressions and the secretion of immunoglobulin A can enable evaluation of the impact of human-animal relationships on hen welfare. Indeed, to date, it has remained difficult to determine whether repeated human contact can really be perceived as a positive enrichment by hens. To achieve this, we shall compare facial expressions and immunoglobulin A levels in a batch of hens previously accustomed to human contact for five weeks with a batch of hens unused to such contact. In both batches, we shall characterise transient emotions by observing facial expressions and assaying swabs of secreted immunoglobulin A following short-term tests of a human presence. The long-term impact of human-animal relationships on the health and welfare of the animals will be assessed from samples of faeces collected at the start and end of the treatment in order to analyse the intestinal microbiota, levels of secreted immunoglobulin A and more general and standard health factors. A transcriptomic analysis and skin colour test will also be performed. The innovative knowledge thus produced could in the longer term enable breakthroughs in the evaluation of well-being using tools that are transposable in the field.

Species concerned

Partnerships

• Joint Research Unit for Reproductive and Behavioural Physiology (UMR PRC), Animal Physiology and Livestock Systems Division (PHASE) Division, INRAE: this project will mobilise the skills of three ethologists, two neurobiologists and a specialist in image processing.
• Joint Research Unit for Infectiology and Public Health (UMR ISP), Animal Health (SA) and Microbiology of the Food Chain (MICA) Divisions, INRAE: two specialists in avian immunology.
• Experimental Unit for Alternative Poultry Systems (UE EASM), Animal Health (SA) and Animal Physiology and Livestock Systems (PHASE) Division, INRAE: expertise in the husbandry of organic poultry.
• External partners: French Poultry Federation, for the supply of organic native hens; two collections of local and native breeds.