Induction of FGF21 expression in the liver and a significant increase in plasma FGF21 concentration have been demonstrated in cows during early lactation, but knowledge about the function of FGF21 in dairy cows remains limited. In order to improve the understanding of the physiological role of FGF21 in dairy cows, the present study aimed to investigate differences in metabolic pathways between dairy cows with high and low hepatic expression of FGF21 at week 1 of lactation (n = 8/group) by liver transcriptomics, targeted plasma metabolomics, and analysis of inflammatory and oxidative stress-related parameters. Dry matter intake, energy balance, milk yield, and energy-corrected milk yield at days 8−14 postpartum did not differ between cows with high and low hepatic FGF21 expression. However, cows with high FGF21 expression showed an upregulation of genes involved in endoplasmic reticulum stress, inflammation, and nuclear factor E2-related factor 2 (Nrf2)-dependent cytoprotection compared to cows with low FGF21 expression at week 1 postpartum (p < 0.05). Concentrations of important antioxidants (tocopherols, β-carotene, and glutathione) in the liver and plasma, trolox equivalent antioxidant capacity in plasma, concentrations of oxidative stress-related compounds (thiobarbituric acid-reactive substances and protein carbonyls), and levels of most acute phase proteins at week 1 postpartum did not differ between cows with high or low FGF21 expression. Moreover, among a total of >200 metabolites assayed in the plasma, concentrations of only 7 metabolites were different between cows with high or low FGF21 expression (p < 0.05). Overall, the results showed that cows with high and low FGF21 hepatic expression had only moderate differences in metabolism, but FGF21 might be important in the adaptation of dairy cows to stress conditions during early lactation.
Keywords: ER stress; dairy cow; early lactation; fibroblast growth factor 21.