Peanut crop residues such as peanut vine are widely used to feed small ruminants as roughage in Asia, where the population of sheep and goat takes a large proportion in the world. Compared to peanut vine, straw is considered as a less nutritious but promising roughage source due to high availability and low price. Extrusion is a process to improve the palatability and digestibility of the feed. Here, we investigated the effects of replacing peanut vine with extruded rape straw on growth performance, apparent nutrient digestibility, energy metabolism, microbial crude protein (MCP) synthesis, and amino acid and fatty acid profiles in the