Follicular fluid proteomic profiling of dairy cows with anestrus caused by negative energy balance

Negative energy balance (NEB) is an important risk factor for the dairy cow's anoestrus. The purpose of the experiment is to screen out differentially expressed proteins (DEPs) in the follicular fluid (FF) of cows with anoestrus caused by NEB and oestrus from positive energy balance (PEB). NEB and PEB holstein cows were selected 14–21 days postpartum according to the serum concentrations of β-hydroxybutyric acid (BHB) and glucose (Glu). Based on the follicle diameter at 55–60 days postpartum, the two groups were assigned into the anoestrus group (NEB-A; n = 6; follicular diameter < 8 mm) and oestrus group (PEB-E; n = 6; follicular diameter: 15–20 mm). Their FF was aspirated in vivo to screen out DEPs, and analysed by bioinformatics. Five DEPs were verified by western blotting (WB). The study identified 367 proteins. Compared with PEB-E, NEB-A expressed 135 downregulated DEPs and 37 upregulated DEPs. RBP4 (retinol-binding protein 4), adiponectin B, SOD (superoxide dismutase), IGF2 (insulin-like growth factor 2), and CRP (C-reactive protein) were verified by WB, their may have confirmed that cellular lipid metabolism, oxidative stress, and cellular immune function are related to follicular development and anoestrus.Highlights367 proteins identified in the Follicle fluid of dairy cows 55–60 days postpartum.In the Negative energy balance-anoestrus group, 172 differentially expressed proteins were identified—135 upregulated DEPs and 37 downregulated DEPs.Confirmed that postpartum Negative energy balance may affect cows' oestrus behaviour or performance during early lactation by lipid metabolism, the IGF regulation system, and immune and complement systems.