Contribution of essential amino acids to glucose metabolism and lactose secretion in late lactation dairy cows

摘要

Increased protein supply is known to increase both milk and milk lactose yields as well as whole body rate of appearance (Ra) of glucose (Lapierre etal, 2010). However, despite earlier observations reporting that arterial glucose would not be the onlyprecursor of milk lactose (Bickerstaffe et al., 1974), little attention has been paid to the potential contribution of amino acids (AA) to mammary lactose synthesis. Although, Bequette et al. (2006) recently demonstrated in vitro that some essential AAcould contribute to mammary lactose synthesis, no in vivo study has examined the contribution of essential AA to milk lactose secretion and if that contribution would be altered by AA provision. Therefore, the objective of this study was to examine if increased supply of essential AA, in excess of requirement, would affect the contribution of glucose to lactose synthesis in lactating daily cows.