Topics: Rumen microbiology, rumen action physiology, Metabolic Processes, metabolic Pathways, Ration Formulation, Feed Additives, Nutritional Disorders, carbohydrate digestion, protein digestion, fats digestion, salivation, digestion physiology, Reticulorumen Motility, rumination, Eructation, Belching, Carbohydrate Metabolism, Volatile Fatty Acid Production, Glucose production, Protein Metabolism, Ruminal protein degradation, hydrolysis, Deamination, Urea metabolism, Ammonia Assimilation, Fat Metabolism