Antibiotics consumption in animal production has become into a public health problem during the last decade. The development of multiresistent microorganisms to certain antibiotics means a high sanitary cost. Spain is one of the main consumers of antibiotics in animal production in the European Union, and rabbit and poultry production are specifically responsible of these data. Thus, both at a European and at Spanish level, the reduction or even the elimination of antibiotics in animal production is a challenge during the last years.</p><p>There are several ways to face up to these problems, and nutritional techniques have become the most developed. However, this project is focused in alternatives based on the animal. We hypothesise that when an animal is in good health and welfare, its resilience is increased, so they can cope with the environment, including possible infections, which traditionally have been treated with antibiotics.</p><p>Giving the animals an optimum husbandry environment could be traduced into a great opportunity to enhance the capacity to cope with diseases without the need of antibiotics administration. This improvement in management and environment can be treated from different points of view: an increase in air quality, a reduction in infective pressure throughout cleaning and disinfection programmes or even animal husbandry alternatives (e.g. stocking density, mixing animals, etc.). These techniques are usually simple and easily adaptable to different circumstances, and farmers can perform them without big changes in the production systems. Anyway, they must be accurately assessed from a global approach, including their economic viability.</p><p>Thus, the main objective of this project is the assessment of techniques addressed to the improvement of health and welfare conditions of broiler chickens and growing rabbits with the intention of eliminating the use of antibiotics. These techniques are based on: i) improvement of air quality, ii) improvement of cleaning and disinfection protocols, iii) altering stocking density and group sizes and iv) the use of slow growing strains in broiler chickens. The health status will be assesses, as well as the immune response, the effect on microbiota, the presence of antibiotic resistant microorganisms and the economical viability of each proposed technique.