Hepatic gene expression involved in glucose and lipid metabolism in transition cows: Effects of fat mobilization during early lactation in relation to milk performance and metabolic changes

Abstract

Insufficient feed intake during early lactation results in elevated body fat mobilization to meet energy demands for milk production. Hepatic energy metabolism is involved by increasing endogenous glucose production and hepatic glucose output for milk synthesis and by adaptation of postcalving fuel oxidation. Given that cows differ in their degree of fat mobilization around parturition, indicated by variable total liver fat concentration (LFC), the study investigated the influence of peripartum fat mobilization on hepatic gene expression involved in gluconeogenesis, fatty acid oxidation, ketogenesis, and cholesterol synthesis, as well as transcriptional factors referring to energy metabolism. German Holstein cows were grouped according to mean total LFC on d 1, 14, and 28 after parturition as low [<200 mg of total fat/g of dry matter (DM); n = 10], medium (200-300 mg of total fat/g of DM; n = 10), and high (>300 mg of total fat/g of DM; n = 7), indicating fat mobilization during early lactation. Cows were fed total mixed rations ad libitum and held under equal conditions. Liver biopsies were taken at d 56 and 15 before and d 1, 14, 28, and 49 after parturition to measure mRNA abundances of pyruvate carboxylase (PC); phosphoenolpyruvate carboxykinase; glucose-6-phosphatase; propionyl-coenzyme A (CoA) carboxylase α; carnitine palmitoyl-transferase 1A (CPT1A); acyl-CoA synthetase, long chain 1 (ASCL1); acyl-CoA dehydrogenase, very long chain; 3-hydroxy-3-methylglutaryl-CoA synthase 1 and 2; sterol regulatory elementbinding factor 1; and peroxisome proliferator-activated factor α. Total LFC postpartum differed greatly among cows, and the mRNA abundance of most enzymes and transcription factors changed with time during the experimental period. Abundance of PC mRNA increased at parturition to a greater extent in high-and medium-LFC groups than in the low-LFC group. Significant LFC × time interactions for ACSL1 and CPT1A during the experimental period indicated variable gene expression depending on LFC after parturition. Correlations between hepatic gene expression and performance data and plasma concentrations of metabolites and hormones showed time-specific relations during the transition period. Elevated body fat mobilization during early lactation affected gene expression involved in gluconeogenesis to a greater extent than gene expression involved in lipid metabolism, indicating the dependence of hepatic glucose metabolism on hepatic lipid status and fat mobilization during early lactation.

Transcriptomic Changes in Ruminal Tissue Induced by the Periparturient Transition in Dairy Cows

“…These results agree with those published earlier this year (Weber et al, 2013) which showed similar patterns of expression during the transition Science Publications AJAVS period. ATF3 is an inducible transcription factor whose expression is enhanced by high levels of circulating fatty acids and glucose (Zmuda et al, 2010).…”

0309 Systematic profiling of short tandem repeats in the cattle genome

“…PRKG1 was identified as one of 20 genes associated with milk fatty acid traits in Holstein (Li et al 2014), and its functions include calcium channel regulator activity and cGMP-dependent protein kinase activity. This study also identified ACSL1 associated with the milk fatty acid traits (Li et al 2014) and supported by other studies (Widmann et al 2011;Gao et al 2013;Weber et al 2013). Other identified genes in our current study are involved in somatic cell score and meat quality traits, such as GRIN2B (Wu et al 2014) and PLXNA4 (Strillacci et al 2014).…”

Endogenous and dietary lipids influencing feed intake and energy metabolism of periparturient dairy cows

“…In cows fed a total mixed ration with 6% rumen-protected fat during mid-lactation, gene expression of glucose-6-phosphatase was reduced by a factor of 2.9 [87]. Therefore, mobilization of fatty acids from fat depots and feeding rumen-protected fat increase hepatic fat content [85,87] and may affect gene regulation involved in glucose synthesis in liver of high-yielding dairy cows.…”

“…The relative contributions of substrates for gluconeogenesis change around calving, and glucose production from lactate significantly increases by 10% with propionate being the most important substrate [64,80,83]. Accordingly, gene expression of the mitochondrial phosphoenolpyruvate carboxykinase increases around calving, which is closely linked to gluconeogenesis from lactate [84,85]. Endogenous glucose production was not affected when a diet was fed containing 7% rumen-protected fat [34] but was reduced by a diet supplemented with 50-g/d conjugated linoleic acid [86].…”

“…Diets with elevated fat content and greater fat mobilization during the transition period affects hepatic gene expression of enzymes involved in gluconeogenesis. Gene expression of pyruvate carboxylase increased more in cows with greater body fat mobilization after parturition [85]. In cows fed a total mixed ration with 6% rumen-protected fat during mid-lactation, gene expression of glucose-6-phosphatase was reduced by a factor of 2.9 [87].…”