Omission of dry period or milking once daily affects metabolic status and is reflected by mRNA levels of enzymes in liver and muscle of dairy cows

Abstract The objective of this study was to study the mRNA expression of bovine hepatic and muscular genes according to metabolic status in early lactation influenced by different milking regimes. Control-cows (C, n =12) were dried off 56 days before calving and were milked twice daily after parturition. Cows milked once daily (ODM, n =12) were dried off similarly to the C-cows, but were milked only once daily during the first four weeks of lactation. Continuously milked cows (CM, n =12) were milked twice daily throughout the gestation–lactation cycle. Muscle biopsies were obtained within 24 h after calving and at weeks 6 and 16 post partum (pp). Liver biopsies were performed one week before parturition, within 24 h after calving and at weeks 2, 4, and 8 pp. Muscle samples were analyzed for the mRNA abundance of the facilitated glucose transporter, members 1 and 4 (SLC2A1, SLC2A4), the insulin receptor (INSR), lactate dehydrogenase A (LDHA), acyl-CoA dehydrogenase very long chain (ACADVL), enoyl CoA hydratase (ECHS1), and actin alpha 1 (ACTA1). Liver samples were examined for the mRNA abundance of facilitated glucose transporter, member 2 (SLC2A2), carnitine palmitoyltransferase 1A (CPT1A), acyl-CoA dehydrogenase very long chain (ACADVL), glycerol-3-phosphate acyltransferase (GPAM), phosphoenolpyruvate carboxykinase 2 (PCK2), citrate synthase (CS), tyrosine aminotransferase (TAT) and cathepsin L1 (CTSL). In skeletal muscle, transcript abundances of INSR and SLC2A1 were not affected by treatment, whereas SLC2A4 mRNA expression tended to be lower in CM-cows in comparison with C-cows ( P =0.07) and ODM-cows ( P =0.09). Muscular mRNA levels of LDHA, ACADVL and ACTA1 were not affected by the milking regimen. ECHS1 was down-regulated in CM-cows compared to C-cows ( P =0.0009) and in tendency compared to OD-cows ( P =0.08). All genes, except ECHS1, were strongly influenced by the sampling time point. In liver samples, metabolic status was reflected by marked changes in various mRNA levels. In CM-cows, higher CPT1A and PCK2 transcript abundances were found compared to C- ( P P P =0.09 and P =0.0003 for comparison with C and CM-cows, respectively). The abundance of CTSL was lowest in C-cows compared with both remaining groups ( P This shows that the improved metabolism was also reflected by changes in muscular and hepatic expression of some key enzymes particularly in CM-cows.