Global livestock production has been moving toward the removal of antimicrobial growth promoters in feed. Enteric disease, however, has been one of key problems in livestock production. In the era of AGP free production with existing enteric diseases, understanding and efforts to enhance intestinal health of young animals is the primary goal of successful livestock production. This special issue targets to invite review papers and research papers from frontier scientists in the areas of nutrition, immunology, physiology, and veterinary science with direct application to monogastric animals. Journal of Animal Science and Biotechnology is a leading open access journal publishing innovative research across agriculture, dairy and animal science.