Effects of phytogenic substances on rumen fermentation and methane emissions: A proposal for a research process

Phytogenic substances such as plants, parts of plants and secondary products of herbal origin have gained attention in animal nutrition in recent years. More efficient feed conversion, improved animal health as well as reduced CH4 emissions are important objectives for use of phytogenic substances in ruminant nutrition. A multi stage program is proposed for nutritional assessment and to study the influence of phytogenic substances on rumen fermentation, CH4 emissions, animal health and performance, food safety and environmental impact. The program includes five stages being: (1) Botanical characterization of the plant(s) and their composition, (2) Analytical characterization of the active phytogenic substance(s), (3) In vitro studies to test effects of substances on rumen fermentation and methanogenesis (i.e., screening), (4) In vivo studies (e.g., feed intake, rumen fermentation, CH4 emissions) and, (5) Long term feeding studies with target animal species/categories (e.g., animal health and performance, quality and safety of food of animal origin, environmental impact, adaptation of microbes). Details of the program and its potential importance are discussed.