Diverse feedstuffs and feed additives (enzymes, prebiotics, probiotics, phytogenic compounds, etc.) are being used to address two major challenges of the current monogastric animal industry: cost-effective and antibiotic-free animal production. Furthermore, the addition of selected feed additives in alternative feedstuffs enhances nutrient utilization, promotes gut health and overall performance of animals, which is critical for the animal feeding program in the post-antibiotic era. This special issue is to exchange the recent advances in the use of diverse feedstuffs and feed additives and their interplay with the gut health of monogastric animals (Poultry, Pig, and Fish) for improving animal production. Journal of Animal Science and Biotechnology is a leading open access journal publishing innovative research across agriculture, dairy and animal science.