Leptin mediates discriminate response to feed restriction in feed efficient pigs

Abstract

Genetic mechanisms that control feed efficiency (FE) and feed intake are not well understood. Residual feed intake (RFI) is a measure of FE, in which low RFI designates high FE. Transcriptional profiling coupled with serum metabolite analyses were used to identify genes and pathways that respond to a feed restriction (FR) in high or low RFI pigs. Low RFI (n=10) and high RFI Yorkshire pigs (n=10) of ~82 kg were fed ad lib. or fed 80% of maintenance for 7 days in a 2x2 factorial treatment design. Microarray analysis declared 6,114 genes in fat and 305 genes in liver as differentially expressed (DE) in response to FR and 311 fat genes and 147 liver genes due to RFI. Functional annotation of DE genes due to RFI in fat indicates that pathways such as K+ transport and monocarboxylic acid metabolism were overrepresented. Genes that were DE due to FR in fat overrepresented many pathways, including TCA cycle, apoptosis, and MAPK signaling. Concentrations of serum T3 and glucose were higher in the low RFI vs. high RFI pigs. Serum leptin concentration was decreased by FR in high RFI pigs but had the opposite effect in low RFI pigs. Leptin expression was 2.4‐fold down‐regulated in the low RFI pigs and in silico pathway analysis indicates that leptin had the highest number of interacting neighbors among genes that were DE due to RFI in fat. Leptin may play a key role in determining pathways that respond to FR in feed efficient pigs. USDA‐NRI‐2005‐3560415618