Summary: Animal, Gut, Microbiome-Nutrition in the 21st Century

Knud Erik Bach Knudsen, PhD
Department of Animal Science
Aarhus University, Aarhus, Denmark

The world’s livestock sector is growing at an unprecedented rate due to a combination of population growth, rising incomes and urbanization. The challenge for the 21st Century is to improve the efficiency of the livestock production systems without the use of agents that can lead to antibiotic resistance at the same time as health and welfare are kept optimal. Efficient degradation and absorption of nutrients from the gut and the maintaining of a diverse and balanced microflora are in this context key elements for high feed efficiency and animal health. A multitude of processes occur within the gut related to digestion, fermentation, absorption, endocrine hormone release, immunity and energy metabolism. Many of these processes are carried out in close collaboration with the commensal microbiota which is pivotal not only for the degradation of otherwise indigestible complex carbohydrates and other dietary constituents but also for competitive exclusion of pathogens, production of antimicrobials, etc. The microbiota that reside in the gut encompass hundreds of different microbial species. The diversity of the microflora can be influenced by the dietary composition, particularly the carbohydrates which are the main substrates for the microflora, and by the host’s genotype. The outcome of the anaerobic fermentation processes of feed residues is production of short-chain fatty acids, gases, urea and microbial growth along with an array of small organic molecules that not only have significant impact on the gut itself but also on other organs through absorption. The small molecules originating from the diet, the host and from the microbes are also likely to have important functions in keeping the relationship between hosts and their commensals in balance. A “healthy” gut is an important prerequisite to reduce production losses and reduce the use of antibiotics due to disturbances of the gastro-intestinal functions that often occur during the lifetime of a production animal, for example disturbances caused by pathogens resulting in diarrhoea. The presentation will address some of the aspects related to the diet-gut-animal interaction such as use of prebiotics, enzymes, etc. in relation to feed efficiency and gut health.