title: The effect of a progesterone/estradiol ear implant on the performance of young beef steers.
abstract: A progesterone/estradiol ear implant was tested over a 84 d feedlot period on 96 young Bonsmara steers which were randomly allocated to implant and control groups. Animals were adapted over 5 d to a complete feed formulated to South African feedlot standards. Health aberrations were observed and feed intake, mass gain and slaughter data were recorded. The implant group elicited a 23.2 kg gain per animal (P less than 0.01). Mean treatment feed intakes varied marginally but the implant group showed a 14.91% feed to gain improvement over controls. Warm carcass dressing percentage showed an overall improvement of 4.96% for both groups. Bloat incidence was calculated at 0.98% over 8,064 cattle feedlot days. Mortality was 2.08% and 12 animals were considered to be chronic bloaters. This may have been due to the high proportion of fine particles in the diet. A composite feed sample revealed that 62.48% consisted of particle lengths of 0.5-4mm. The effect of this on ruminal health is briefly discussed. It is concluded that the progesterone/estradiol implant provided greater mass gain and improved feed to gain ratios for treated steers over a control group.
authors.affiliation: Faculty of Veterinary Science, Medical University of Southern Africa, Medunsa.
authors.forename: P A
authors.initials: PA
authors.lastname: Boyazoglu
authors.forename: C
authors.initials: C
authors.lastname: Palmer
authors.forename: M C
authors.initials: MC
authors.lastname: Campbell
authors.forename: M R
authors.initials: MR
authors.lastname: Mankgeli
mesh_terms: D000821:Animal Feed; D000818:Animals; D001835:Body Weight / Q000187:drug effects* / Q000502:physiology; D002417:Cattle / Q000502:physiology*; D004343:Drug Implants; D004423:Ear; D004958:Estradiol / Q000008:administration & dosage*; D011374:Progesterone / Q000008:administration & dosage*
chemical_list: D004343:Drug Implants; D011374:Progesterone; D004958:Estradiol