title: Glucose and lactate absorption and metabolic interrelationships in steers changed from low to high concentrate diets.
abstract: Cannulas were surgically implanted in the portal and mesenteric veins and femoral artery of eight crossbred steers averaging 270 kg. They were given primed, continuous 3-hour infusions of U-[14C]-L-lactate and 2-[3H]- or 6-[3H]-glucose into the jugular vein and para-aminohippuric acid (portal blood flow indicator) into the mesenteric vein before and after being changed from a pelleted alfalfa hay to a pelleted 85% concentrate diet. Blood samples were collected at 20-minute intervals during infusions. Reliable blood flow data were obtained on four of the eight steers during the first infusion; the other four were not infused the second time. Dry matter intake, portal blood flow, net portal D-lactate absorption (P less than 0.10), net portal glucose absorption and L-lactate turnover rate (P less than 0.10) increased as a result of increased concentrate (energy) intake. Glucose turnover rate (P less than 0.10), L-lactate absorbed as a percentage of turnover rate, L-lactate converted to glucose and glucose derived from L-lactate concomitantly decreased. Net portal L-lactate absorption was not affected. The direction of the response for portal blood flow, net portal D-lactate absorption, net portal glucose absorption, L-lactate turnover and L-lactate absorbed as a percentage of turnover was the same as that previously observed in lambs under similar experimental protocol. Differences in responses between lambs and steers for glucose turnover and L-lactate converted to glucose may be attributable to differences in dry matter or energy intake or both.
mesh_terms: D000042:Absorption; D000821:Animal Feed; D000818:Animals; D001786:Blood Glucose / Q000378:metabolism*; D002417:Cattle / Q000502:physiology*; D004032:Diet; D007700:Kinetics; D007773:Lactates / Q000097:blood*; D019344:Lactic Acid; D008099:Liver / Q000098:blood supply; D008297:Male; D011169:Portal Vein; D012756:Sheep / Q000502:physiology
chemical_list: D001786:Blood Glucose; D007773:Lactates; D019344:Lactic Acid