Insights into protein synthesis dynamics of gilts from the same genetic background and age differing in protein deposition

Protein synthesis in Low and High protein deposition (PD) gilts, exploring regulatory pathways within the same genetic background and age were studied. Gilts in Low (157 g/d) and High (219 g/d) PD groups underwent jugular vein cannulation to assess insulin, IGF-I and glucose postprandial responses to the same nutrient intake. ¹³C-valine administration enabled measuring protein synthesis rate and efficiency. Results showed 94% greater (P < 0.05) fractional synthesis rates in the longissimus dorsi and tended (P = 0.10) to a greater (11%) absolute synthesis rate in the liver of High PD gilts. High PD gilts tended (P = 0.10) to be more sensitive to insulin. Transcriptomics analyses in muscle identified 67 up-regulated and 102 down-regulated unique genes. Among the up-regulated genes, four olfactory receptors (OR4L1, OR5D13, OR6B2, OR10R2) and one ribosomal protein (RPS15A) present the highest fold-changes in High vs Low PD gilts. Functional analyses identified six enriched gene ontology terms relate to muscle development, three to protein metabolism and four to signaling pathways. Rap1 signaling and regulation of actin cytoskeleton were over-represented KEGG pathways. High PD gilts exhibit greater protein synthesis and efficiency, with transcriptomic evidence suggesting improved insulin sensitivity and reduced muscle protein degradation.