Submitted to: American Society of Animal Science
Publication Type: Abstract Only
Publication Acceptance Date: 3/1/1997
Publication Date: N/A
Citation: Interpretive Summary:
Technical Abstract: Ergopeptine alkaloids are the major ergot alkaloids present in endophyte-infested (E+) fescue. Ergopeptine alkaloids are excreted via the biliary system; however, ruminants may convert ergopeptines to lysergic acid amides which are excreted via the urine. The objective was to determine excretion sites of ergot alkaloids and to determine urinary clearance or appearance rates in steers exchanged from endophyte-free (E-) to E+ fescue and vice versa. Sixteen Angus steers grazing two E- (0 ergot alkaliods) and two E+ (358-696 ppb ergot alkaloids) fescue paddocks (four/paddock) were studied over a 65-day period. Bile was obtained from all steers via ultrasonography of the gall bladder followed by percutaneous tap using a needle and syringe. Urine samples were collected prior to obtaining bile. Animal weight was used to compute daily biliary alkaloid excretion. Urinary ergot alkaloid and creatinine concentrations were used to calculate urinary alkaloid excretion adjusted for animal weight. The major route of alkaloid excretion was the urine. To estimate rates of appearance or clearance of urinary alkaloids, two steers from each E+ paddock were exchanged with two steers from E- paddocks and vice versa. Within 48 h of exchange from E+ to E-, daily urinary alkaloid output of steers decreased from 0.72 to 0.04 mg, respectively. In contrast, E- to E+ increased from 0.02 to 0.73 mg, respectively. In summary, urine is the major route of alkaloid excretion, and approximately 95 % of the urinary alkaloids were cleared from animals within 48 h.