Optimizing protein nutrition to reduce antibiotic use and the environmental impact of broiler chicken production

This thesis evaluated the effects of dietary crude protein (CP) reduction and the raised without antibiotics (RWA) program on growth performance and nutrient utilization in broiler chickens. Birds were fed either a standard CP (SCP) or a low CP (LCP; 4% points reduction) diet raised without antibiotics or antimicrobial growth promoters (AGP) gut programs. The AGP group received bacitracin methylene Disalicylate (BMD) and an ionophore, whereas the RWA group received a feed additive consisting of a blend of short- and medi-um-chain fatty acids, organic acids, and a polyphenol plant extract, along with a coccidia vaccine. Feed con-version ratio did not differ between RWA and AGP birds at either CP level, indicating that the nutritional strategies evaluated could effectively replace AGP. However, LCP diet treatments consistently reduced growth performance and increased fat deposition compared to SCP diets, independent of gut health manage-ment programs.