Relationship Between FGF - 21 And Energy Metabolism In Dairy Cows

This research is to investigate the variation and relationship among serum FGF-21concentration, FGF-21and its receptors mRNA expression and characteristic parameters relatedto negative energy balance in different energy metabolism state. We also investigate whetherFGF-21level could reflect energy metabolism state; and in this research, we also evaluate thatexogenous FGF-21can mediate favorable effects on body energy metabolism state.10Non-pregnant, non-lactating dairy cattle were randomly allocated in two groups to ourexperiment. The interventions were a controlled-energy diet (0.37Mcal/kg) and amoderate-energy diet (1.48Mcal/kg) during duration of experiment. Blood samples werecollected every day and biopsy were performed in liver and fat tissue collected in14d and35dduring the experiment. In addition,90dairy cattle were selected and allocated in ClinicalKetosis group (CK), and Natural Control group(C).We measured biochemical parameters, serumFGF-21, leptin and insulin levels by commercial ELISA kits.The results showed that serum FGF-21levels were significantly higher in both groupstreated with a controlled-energy diet, while FGF-21levels in both groups treated withmoderate-energy diet were just the opposite. In a synthesis analysis of two groups inexperimental phase, FGF-21levels was significantly positively correlated with serum leptinlevels while an inverse relationship of FGF-21with blood glucose and BHBA levels was found.In a combined population research of all90cows, when BHBA level increased over1.6mmol/L,FGF-21level tended to decline below322.38ng/ml.Serum FGF-21and mRNA expression in liver were up-regulated in the situation of energydeficiency. Meanwhile, energy deficiency also up-regulated the expression of PPARα, PPARγand βKlotho. Additionally, among FGFRs, FGFR1and FGFR2mRNA expression in liver and fattissue were strongly up-regulated in the situation of energy deficiency while no significantchange was found between FGFR3and FGFR4.Treatment with exogenous FGF21up-regulated serum FGF-21, insulin, BHBA and UAlevels. In addition, injection of exogenous FGF21was associated with increased mRNAexpression levels of βKlotho, PPARα and PPARγ.Conclusion: An inverse relationship of FGF-21with Ketone bodies was found, and FGF-21 could be a characteristic parameters in evaluation and auxiliary diagnosis of energy metabolismstate changes. An increase in FGF-21levels after a controlled-energy diet treatment maycontribute to positive metabolic effect and it will be a new theoretical and pratical basis on thepreventive strategy of dairy cattle with NEB.