The European OMELETTE project has entered a key experimental phase. Its goal is to study how an enriched calcium diet — known to strengthen bone structure and eggshell quality — interacts with environmental factors like confinement. The study led by INNOZH and ANSES aims to better understand how these variables influence metabolism, immunity, and resilience in laying hens.
Experimental
Design: Four Groups for Comparative Analysis
To objectively analyze these effects, the 4,000 hens are divided into four experimental groups of 1,000 each:
- Group 1: Calcium-enriched diet, no confinement
- Group 2: Standard (non-enriched) diet, no confinement
- Group 3: Calcium-enriched diet, with confinement
- Group 4: Standard diet, with confinement
This setup allows researchers to evaluate:
- The individual effect of nutrition
- The individual effect of environment (confinement)
- Any interaction between the two factors
Zootechnical Monitoring and Blood Sampling Schedule
A complete zootechnical follow-up is carried out throughout the study. Blood samples are taken from 40 hens per group at four key stages:
- 17 weeks: Start of production — baseline measure before any interventions
- 55 weeks: Before confinement — physiological status under stable conditions
- 57 weeks: Just after confinement — immediate effects on biomarkers
- 90 weeks: Late in production cycle — mechanisms related to health and productivity at older age
Key Biomarkers: Health and Longevity Indicators
Blood samples are analyzed for three major biomarkers:
· Calcitonin: A hormone central to calcium metabolism. Monitoring calcitonin helps assess skeletal integrity and the hen’s ability to maintain bone health throughout the laying cycle — a factor strongly linked to longevity.
· GPX (Glutathione Peroxidase) : A major antioxidant enzyme. High activity of GPX reflects strong resistance to oxidative stress, which is associated with aging processes, performance, and overall well-being.
· Ratio CD4/CD8 : This is an immune balance indicator, showing the proportion between helper T cells (CD4) and cytotoxic T cells (CD8). It provides insight into immune vigilance and the ability to respond to environmental challenges.
Objectives — Towards Better Understanding Longevity and Resilience
The data collected will help:
- Identify factors that contribute to longer productive life in laying hens
- Assess how calcium and confinement affect hen health, welfare, and resilience
- Propose recommendations aimed at optimizing rearing practices across Europe, balancing economic performance with long-term sustainability