Effects of dietary lipid supplementation on enteric methane emissions and feed efficiency in ruminants: A review

Abstract

Enteric methane emissions from ruminant livestock represent a major environmental challenge and a significant loss of dietary energy, thereby reducing feed efficiency and animal productivity. This review examines the effects of dietary lipid supplementation on enteric methane production and feed efficiency in ruminants. Methane formation is closely linked to rumen fermentation processes, hydrogen availability, and the activity of methanogenic archaea. Dietary lipids influence these processes through multiple mechanisms, including reduction of fermentable organic matter, biohydrogenation of unsaturated fatty acids, suppression of rumen protozoa and methanogens, and shifts in volatile fatty acid profiles toward increased propionate production. In addition to mitigating methane emissions, lipid supplementation increases dietary energy density, which can enhance feed utilization efficiency and animal performance when appropriately managed. However, excessive lipid inclusion may negatively affect dry matter intake, fiber digestibility, and rumen microbial activity. The review highlights that the effectiveness of lipid supplementation depends on lipid type, inclusion level, and production system. Overall, dietary lipid supplementation presents a viable nutritional strategy for reducing enteric methane emissions while improving feed efficiency, provided that its limitations are carefully addressed through balanced diet formulation.