THE ROLE OF FEED ADDITIVES AND GENOTYPE IN MITIGATING THE EFFECT OF STRESSORS ON GROWTH, INTESTINAL HEATLH AND MEAT QUALITY OF BROILER CHICKENS

The future growth of the poultry industry has to be based on new strategies to achieve consumers’ confidence, product quality and safety, variability of products while achieving a sustainable agriculture. Nowadays healthy animals play an essential role to thrive towards a sustainable European and global food supply. Therefore, it is necessary to adopt a holistic approach when it comes to sustainability besides meeting animal welfare, food safety, affordability and environmental protection standards. In addition, food security and sustainable practices have been questioned and become even more critical in the recent years after the pandemic situation thus, the need to find new alternatives to deal possible emerging challenge situations or the previous ones e.g. the prohibition of the use of antibiotic growth promoters in poultry, lead to an active research with the objective to develop multiple management and nutritional strategies to improve the overall animal welfare starting from the intestinal health and performance of the birds. In this context, feed additives such as phytochemicals, have the greatest feedback because they have promoted growth and health thanks to their antioxidant, antimicrobial and anti-inflammatory properties. On the other hand, related to sustainability issues in poultry production, the use of feed additives or different genotypes such as local breeds, seem to be able to mitigate challenge situations like climate change and to play an important role. Therefore, they are essential to ensure food security, environmental preservation, and economic viability. Feed additives play a crucial role on enhancing poultry production efficiency and sustainability as they can improve growth rates, feed conversion ratio, gut health, and the overall productivity. In particular, phytogenics are plant-based additives that can improve feed intake, digestion, and immune function. Then, organic acids are more focused on maintaining gut health and on the reduction of pathogenic bacteria on the intestinal environment. Finally, local breeds are becoming popular because of their greater adaptation to local conditions or possible challenge situations, like different local climatic conditions, diseases or diets based on local ingredients that consequently reduces the need of medication, exportation or specialised housing. Moreover, local breeds show an economic viability as their local products can reach a higher market price because of their specific qualities and consumer preferences. In this context, there is an interest on analysing the entire value chain from the sustainability of the breeds to animal health and product quality to consumer expectations. Thus the main objectives of the present thesis are to evaluate the effect of different dietary supplementation strategies i.e., polyphenols as feed additives (grape seed extract) and organic acids (sodium butyrate) on growth performance, carcass traits, meat quality and myopathy occurrence in broiler chickens besides the effect at the gut health level as for morphology and immune response, in order to elucidate mechanisms of actions of grape seed tanins and the sensorial properties of the meat, namely for the dietary sodium butyrate. In addition, the present thesis evaluates the response of different genotypes i.e., 1 commercial crossbreed and 2 Italian local breeds, reared under two different challenge conditions e.g. heat stress, by their productive performance, carcass traits, and meat rheological, nutritional, and sensorial properties. To achive these objectives, three trials were designed and realized which results are resumed hereby.