title: Supplementing previously treated anestrous dairy cows with progesterone does not increase first-service conception rate.
abstract: The objective of this study was to investigate the effect of supplementing previously treated anovulatory anestrous (AA) dairy cows with progesterone delivered intra-vaginally for 7 days, commencing 4 or 5 days after insemination, on first-service conception rate. A clinical trial, involving 990 AA dairy cows in 14 dairy herds, was conducted during the 2002/2003 breeding season. On Day -8, all cows were treated with a progesterone-containing intravaginal device (Cue-Mate). The devices were removed on Day -2; on Day -1, all cows were given 1mg of estradiol benzoate im. Cows in the control group (n = 499) received no further treatments. Cows in the treatment group (n = 491) that had been inseminated on Day 0 or 1 had a new device inserted (on Day 4 or 5), with removal of the device after 7 days. First-service conception rates for the control and treatment groups were not different (35.0% versus 36.7% respectively; P = 0.41). Furthermore, there was no difference in conception rates between cows that had devices inserted on Day 4 or 5 (31.3% versus 37.2% respectively; P = 0.45). In conclusion, supplementation of previously treated AA dairy cows with an intravaginal progesterone-releasing device for 7 days (commencing 4 or 5 days after insemination) did not significantly improve first-service conception rate.
authors.affiliation: Matamata Veterinary Services Ltd., 26 Tainui St., Matamata, New Zealand.
authors.forename: D W
authors.initials: DW
authors.lastname: Hanlon
authors.forename: P J
authors.initials: PJ
authors.lastname: Davidson
authors.forename: A R
authors.initials: AR
authors.lastname: Hittmann
authors.forename: A K
authors.initials: AK
authors.lastname: Joe
mesh_terms: D000282:Administration, Intravaginal; D000780:Anestrus; D000818:Animals; D001947:Breeding; D002417:Cattle / Q000502:physiology*; D004958:Estradiol / Q000008:administration & dosage / Q000031:analogs & derivatives*; D005260:Female; D005306:Fertilization / Q000187:drug effects*; D011374:Progesterone / Q000008:administration & dosage*
chemical_list: C074283:estradiol 3-benzoate; D011374:Progesterone; D004958:Estradiol