title: Ovariectomy as a means of abortion and control of estrus in feedlot heifers.
abstract: Three hundred and six heifers were randomly assigned to treatment groups in a three by six factorial design. Treatments were ovariectomy, melengestrol acetate (MGA), manual abortion, intramuscular estradiol cypionate (ECP) or Prostaglandin F2alpha and untreated controls. The Average Daily Gain (ADG) of the Ovariectomized Group was less (p < .01) during the first 24 days and not different (p > .05) for the total feeding period. Feed intake of the Ovariectomized Group was less (p < .05) than Manual Abortion, Prostaglandin or Control Groups during the first 24 days but essentially the same (p > .05) for the total period. The Prostaglandin Group required fewer days to reach slaughter condition than the Ovariectomy or MGA Groups (p < .05). The only difference in the cost/benefit analysis was in the direct cost of the treatments. Factors other than the various treatments interrupted many pregnancies. The effects of treatments varied with 100% of pregnancies terminated only in the Prostaglandin F2alpha Group.
authors.affiliation: Department of Large Animal Clinics School of Veterinary Medicine Purdue University W. Lafayette, Indiana 47907 USA.
authors.forename: L A
authors.initials: LA
authors.lastname: Horstman
authors.forename: C J
authors.initials: CJ
authors.lastname: Callahan
authors.forename: R L
authors.initials: RL
authors.lastname: Morter
authors.forename: H E
authors.initials: HE
authors.lastname: Amstutz