Metabolic and endocrine profiles and hepatic gene expression in periparturient, grazing primiparous beef cows with different body reserves

The objective was to determine effects of prepartum BCS on metabolic/endocrine profiles and hepatic gene expression and their associations with cow and calf performance in grazing suckled-primiparous beef cows from -49 to 49 days postpartum (DPP). Twenty crossbred cows selected according to expected calving date, were classified at -35 DPP into thin (BCS<4.5) or moderate (BCS≥4.5) BCS groups and blocked by calving date. Blood samples were obtained weekly for metabolite and hormone analyses and liver biopsies were collected at -11, 7, 31, and 49 DPP. Cow BW and BCS were greater in moderate than thin cows throughout the period. Estimated energy intake was greater in moderate than thin cows Moderate BCS cows produced more milk than thin cows at 35 DPP and calves from moderate BCS cows had greater BW and average daily gain than calves from thin cows. Serum leptin tended to be greater while adiponectin was less in moderate than thin BCS cows. Overall serum insulin was less in moderate than thin cows while serum IGF-I during the prepartum was greater in moderate than thin BCS cows. Growth hormone receptor (. GHR) mRNA was 2-fold greater at -11 DPP while GHR1A and IGF1 mRNA were 2.5-fold less at 49 DPP in moderate than thin BCS cows. The I. GFBP2 mRNA decreased in moderate but increased in thin BCS cows from -11 to 49 DPP. These results were associated with changes in body reserves during prepartum and may indicate that prepartum differences in BCS lost can affect nutrient partitioning towards the mammary gland, and subsequent milk production and calf weight.