Doctoral Dissertations

Date of Award

5-1994

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Animal Science

Major Professor

John C. Waller

Committee Members

Richard N. Heitmann, James D. Quigley III, Michael O. Smith, John W. Koontz

Abstract

Three trials were conducted to evaluate the alterations of energy metabolism in ruminants fed a forage or concentrate based diet supplemented with or without lasalocid. Trials 1 and 2 were designed in a 2 x 2 Latin Square using 4 post-weaned wethers (avg BW = 57 kg) in each trial. Trial 1 used a high forage diet made up of 75% alfalfa pellets and 25% rolled corn. Trial 2 used a high concentrate diet of 75% rolled corn and 25% alfalfa pellets. Wethers were equipped with indwelling catheters in the portal, hepatic, and mesenteric veins, caudal aorta and caudal vena cava. A series of 6, 12 ml samples were taken from femoral artery, hepatic, portal and femoral veins and whole blood was analyzed for PAH, acetoacetate (ACAC), beta-hydroxybutyrate (BOHB), glucose and lactate. Plasma was analyzed for non-esterified fatty acids (NEFA) and VFA. In Trial 1 splanchnic blood flow rates were decreased (P < .01) by lasalocid, while peripheral blood flow was increased (P < .01) . Lasalocid supplementation in Trial 1 increased (P < .01) hepatic production of glucose and lactate by portal drained viscera (PDV). Production of BOHB by hepatic tissue in Trial 1 was lower (P < .05) and animals supplemented with lasalocid had increased (P < .01) PDV release of propionate. In Trial 2, portal blood flow was reduced (P < .01) in animals supplemented with lasalocid. Glucose release by the liver was similar between treatments in Trial 2 despite increased (P < .05) PDV release in wethers fed Lasalocid. Unlike Trial 1, wethers fed a high concentrate diet had decreased (P < .01) PDV release of BOHB. Trial 3 was conducted using a rumen epithelial cell incubation technique. Five sheep were used, fed a high forage diet with or without supplemental lasalocid. Rumen epithelium was collected after slaughter and incubated in media containing acetate, propionate and butyrate. Acetoacetate, BOHB, lactate and pyruvate increased through 120 min in both treatments indicating continued cellular metabolism. No differences between treatments in any metabolite concentrations were detected. In these trials no evidence was observed to substantiate possible effects of ionophores on host cell metabolism.

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