GLUCOSE AND AMINO-ACID-TRANSPORT AND METABOLISM IN FLAT DUODENAL SHEETS OF DAIRY-CATTLE AT 3 STAGES OF LACTATION

The apparent duodenal transport and metabolism of amino acids and gluc ose in early-, mid-, late- and non-lactating dairy cows was investigat ed. K-m values for glucose were not affected by stage of lactation. Th e capacity (Isc(max)) of duodenal sheets to transport glucose was grea ter in lactating than in non-lactating cows. Lactating cows had a grea ter transport capability for amino acids than non-lactating cows. Duod enal sheets of early-lactation cows metabolized a greater percentage o f absorbed glucose carbon to carbon dioxide than cows in mid-, late- a nd non-lactating cows.