show Abstracthide AbstractRuminal microorganisms are an important component of nutrient digestion in ruminants, and their structural composition and function can be influenced by the structure of the diet. Feeding high concentrate diets (HCD) has become a common practice to meet the nutritional needs of ruminants. However, it is currently unclear what changes will occur in the composition and function of the rumen microbiota in goats fed with HCD. Therefore, this study used metatranscriptomics to investigate the effects of concentrate diet level on rumen microbiota composition and function in goats.