title: Injection of a dopamine antagonist into Holstein steers to relieve symptoms of fescue toxicosis.
abstract: Two experiments were conducted to determine whether administering a dopamine antagonist to steers fed endophyte-infected (E+) tall fescue would increase serum prolactin (PRL) and reduce rectal temperature. Steers in both experiments were housed in environmentally controlled chambers (32 degrees C; 50% relative humidity). In Exp. 1, 10 steers were allotted randomly to receive s.c. injections of either 0, .006, .03, or .06 mg of Ro 24-0409 (dopamine antagonist)/kg BW. The experiment was designed in four phases: endophyte-free seed (E-) without antagonist (d -11 to 0); E- with antagonist (d 0 to 7); E+ with antagonist (d 7 to 28); E+ without antagonist (d 28 to 38). In Exp. 2, 22 Holstein steers were allotted randomly to the same treatments and design, except three steers were maintained on E- without antagonist. Steers were fed individually with intakes measured daily. In Exp. 1, feed intake and rectal temperature were not improved (P > .05) by antagonist injection. In Exp. 2, antagonist injections increased (P < .05) PRL. Ingestion of E+ decreased (P < .05) feed intake and serum PRL. Antagonist injection decreased (P < .05) rectal temperature and increased (P < .05) serum PRL.
authors.affiliation: Department of Animal Sciences, University of Missouri, Columbia 65211, USA.
authors.forename: M D
authors.initials: MD
authors.lastname: Samford-Grigsby
authors.forename: B T
authors.initials: BT
authors.lastname: Larson
authors.forename: J C
authors.initials: JC
authors.lastname: Forcherio
authors.forename: D M
authors.initials: DM
authors.lastname: Lucas
authors.forename: J A
authors.initials: JA
authors.lastname: Paterson
authors.forename: M S
authors.initials: MS
authors.lastname: Kerley
mesh_terms: D000818:Animals; D001831:Body Temperature / Q000502:physiology; D001835:Body Weight / Q000502:physiology; D002417:Cattle; D002418:Cattle Diseases / Q000097:blood / Q000188:drug therapy* / Q000503:physiopathology; D004032:Diet / Q000662:veterinary; D018492:Dopamine Antagonists / Q000008:administration & dosage / Q000627:therapeutic use*; D004435:Eating / Q000502:physiology; D004881:Ergotism / Q000188:drug therapy / Q000503:physiopathology / Q000662:veterinary*; D007279:Injections, Subcutaneous; D007546:Isoquinolines / Q000008:administration & dosage / Q000627:therapeutic use*; D008297:Male; D010939:Plant Poisoning / Q000188:drug therapy / Q000503:physiopathology / Q000662:veterinary*; D011388:Prolactin / Q000097:blood; D012881:Skin Temperature / Q000502:physiology
chemical_list: D018492:Dopamine Antagonists; D007546:Isoquinolines; C106326:Ro 24-0409; D011388:Prolactin