Emulsifiers in poultry nutrition–molecular mechanism of lipid metabolism and energy utilization: A meta-analysis and KEGG mapping

The feed energy derived from fat remains relatively low because young poultry have limited fat digestibility and inefficient lipid metabolism. This study aimed to evaluate the effectiveness of emulsifiers in regulating lipid metabolism and increasing lipase activity in poultry. A quantitative review of 57 studies (2015-2025) revealed that emulsifier supplementation significantly upregulated genes associated with lipogenesis, including diacylglycerol O-acyltransferase 2 (DGAT2), and increased lipolysis through the upregulation of perilipin 1 (PLN1). It also increased the activities of lipoprotein lipase and total lipase. Kyoto Encyclopaedia of Genes and Genomes (KEGG) mapping also suggested that fatty acid biosynthesis (gga00061), β-oxidation (gga00071), the PPAR signalling pathway (gga03320), cholesterol metabolism (hsa04979), and the regulation of lipolysis (gga04923) in adipocyte regulation pathways were synergistically activated. Taken together, these pathways suggest that emulsifiers improve lipid turnover, oxidative metabolism and lipoprotein formation in broiler chickens. In summary, emulsifiers modulate lipid metabolism at the molecular level, which offers mechanistic support for improving energy utilization and may also aid in developing precision nutrition strategies in poultry.