Effects of Endophyte-Infected Fescue and Cimetidine on Respiration Rates, Rectal Temperatures and Hepatic Mixed Function Oxidase Activity as Measured by Hepatic Antipyrine Metabolism in Sheep

Abstract

The effects of endophyte-infected fescue (Kentucky 31) hay and cimetidine on respiration rates, rectal temperatures and hepatic antipyrine uptakes of three mature ewes were measured in 15 experiments. Hepatic antipyrine uptake was measured as an indirect indicator of hepatic mixed-function oxidase (MFO) activity. Five experiments on each ewe were conducted during consumption of endophyte-free (one exp/ewe, control), endophyte-infected (two exp/ewe, EIF) and endophyte-infected fescue hay plus cimetidine (800 mg/d i.v., two exp/ewe, EIFC). Respiration rates increased (P < .05) 2.6-fold after 11 d on EIF from 26 to 68 and decreased (P < .025) to 27 breaths/min after 4 d of cimetidine treatment. Rectal temperatures increased (P < .05) 1.1°C after 8 d on EIF. Cimetidine lowered temperatures to control levels by d 4. Endophyte-infected fescue hay increased (P < .05) hepatic antipyrine uptake 70% after 11 d, but uptake was lowered to control levels by cimetidine by d 4. Increased respiration rates and rectal temperatures in animals consuming EIF seem to be related to increased MFO activity. Cimetidine reversed some of these effects.