Probiotics, Prebiotics, and Synbiotics in Pigs and Poultry: A Review of Gut Health, Performance, and Environmental...

The cardinal Physiology of Gut Health in monogastric animals such as swine and poultry is vital. It is critical for digestive efficiency, immune status, and production levels. This system is related not only to the digestion and absorption of nutrients from feed ingredients contributing to growth and feed utilization efficiency but also to having a strategic microbiota that supports immunity and pathogen resistance, as well as metabolic support. Gut disease, for example, bacterial, viral, or parasitic infection, diet, or stress, can reduce nutrient digestion and absorption. They can also suppress the immune system and render patients more prone to disease. These are efficiency degradations and increase veterinary and husbandry costs. In addition, nutrient absorption because of deteriorated gut health can affect the environment in different ways: removal of nutrients through leaching and the release of gases (including CH₄ and NH₄). These pressures have led to a focus on the gut in animal research to improve the welfare of animals and ensure sustainable practices in animal production. Recent studies have included the use of probiotics, prebiotics, and other feed additives to enhance the positive effects of the gut microbiota. These are also intervention points to increase nutrient absorption and animal well-being, in turn sustainability. Such approaches are expected to promote a stable microbial community with less dependence on the use of antibiotics, less waste generation, and less environmental impact from animal farming. This review provides a critical evaluation of the current literature on gut health in monogastric livestock, with pigs and poultry as the principal focus. We also considered the impact of gut health on production efficiency and Environmental sustainability. Current progress in nutritional modulation of gut health for increased productivity, enhanced animal welfare, and better profitability are presented. Gut-related biological mechanisms are linked to practical nutritional strategies, and subsequently to animal welfare, production efficiency, and environmental effects, offering a coherent concept for moving from mechanism to system-level sustainability.