HOW DIFFERENT HUSBANDRY CONDITIONS INFLUENCE GUT MICROBIOME, CORTISOL LEVEL AND BEHAVIOUR IN LAMBS?

The gut microbiota-brain axis is a bidirectional pathway through which the brain regulates the activity of the gutand vice versa. The intestinal microbiota was proven to influence and be influenced by stress-related responsescaused by management conditions. The aim of this work was to evaluate whether different husbandry conditionsin lambs influenced gut microbiome (composition and diversity), cortisol level and behaviour. Fifteen Sarda breedlambs, aged 6 months, were randomly assigned to three groups of 5 animals each: Isolation (tactile and visualisolation; 3 h/day for 8 weeks); Enriched (in group in a outdoor grassy pen with a new enrichment each week; 3h/day for 8 weeks); Control (habitual farm environment). Every week, 2 video-recordings of 1-hour each werecollected respectively during and after each treatment, and analysed using a scan sampling technique (60 scansper video). Every two weeks hair was collected from the right shoulder using a shave and re-shave method.Cortisol concentration was measured by means of an ELISA test conducted on hair samples and expressed aspg/ml. At week 8 faecal material was collected directly from the rectal ampulla and immediately frozen at -20°Cuntil DNA extraction was performed using a QIAmp DNA Stool kit (Qiagen, Hilden, Germany). DNA quality andquantity were assessed using a NanoDrop ND-1000 spectrophotometer (NanoDrop Technologies, Wilmington, DE,USA). The microbiota of enriched animalswas clearly different from the other two groups and showed lowerwithin group variability. During treatment, only isolated sheep showed escape attempts (23% of scans during thefirst week) and freezing (58% of scans during the first week). In the home pen, after treatment, lambs did not showany stress-related behaviour. After one month of treatment, hair cortisol increased only in the isolated group. Inconclusion, differences in microbiome could be related to the different stimulating enrichment and addition ofgrass on the diet. Although, from a behavioural point of view, sheep apparently habituated to the isolation,increase in cortisol levels could be related to experiencing a stressful situation. This study was approved by theItalian National Ethical Commission (authorization n°457/2016-PR) and supported by MIUR-PRIN2015 (Grant2015Y5W9YP).