Identification of Key Proteomic Markers for Enhanced Conjugated Linoleic Acid Biosynthesis in Lactating Goats via Linseed Oil Supplementation

This study investigated the effects of linseed oil (LO) supplementation on conjugated linoleic acid (CLA) biosynthesis in lactating Saanen goats. Goats (DIM = 96 ± 14 days) were divided into control (<i>n</i> = 6) and LO treatment (<i>n</i> = 6) groups. LO supplementation was implemented in both short- and long-term experimental settings. Short-term LO supplementation significantly increased <i>trans</i>-11 vaccenic acid and <i>cis</i>-9,<i>trans</i>-11 CLA in milk fat without affecting lactation performance. Using two-dimensional gel electrophoresis, we identified six upregulated proteins in milk somatic cells, including translocon-associated protein (SSRD), succinyl-CoA ligase (SUCB2), ATP synthase subunit (ATPD), stress-70 protein (GRP75), NADH dehydrogenase (NDUFS2), and cytochrome complex QCR1. Long-term LO supplementation enhanced milk fat content and <i>cis</i>-9,<i>trans</i>-11 CLA levels, while significantly elevating the mRNA expression of stearoyl-CoA desaturase (SCD) and all previously identified proteins-including proteasome 20s subunit alpha 5 (PSMA5). These findings extend beyond the known SCD pathway, revealing novel protein markers and potential mechanisms associated with CLA biosynthesis in mammary tissue and milk somatic cells.