title: Intravaginal progesterone devices in synchronization protocols for artificial insemination in beef heifers.
abstract: Two experiments were designed to investigate the administration of intravaginal progesterone in protocols for oestrus and ovulation synchronization in beef heifers. In Experiment 1, cyclic Black Angus heifers (n = 20) received an Ovsynch protocol and were randomly assigned to receive (CIDR-Ovsynch) or not (Ovsynch) a progesterone device between Days 0 and 7. Treatment with a controlled internal drug release (CIDR) device significantly increased the size of the dominant follicle prior to ovulation (12.8 ± 0.4 CIDR-Ovsynch vs 11.4 ± 0.4 Ovsynch) (p < 0.02). Plasma progesterone concentrations throughout the experiment were affected by the interaction between group and day effects (p < 0.004). In Experiment 2, cyclic Polled Hereford heifers (n = 382) were randomly assigned to one of the six treatment groups (3 × 2 factorial design) to receive a CIDR, a used bovine intravaginal device (DIB), or a medroxiprogesterone acetate (MAP) sponge and GnRH analogues (lecirelin or buserelin). All heifers received oestradiol benzoate plus one of the devices on Day 0 and PGF on Day 7 pm (device withdrawal). Heifers were detected in oestrus 36 h after PGF and inseminated 8-12 h later, while the remainder received GnRH 48 h after PGF and were inseminated on Day 10 (60 h). The number of heifers detected in oestrus on Day 8 and conception rate to AI on Day 9 were higher (p < 0.01) in the used-DIB than in the CIDR or MAP groups, while the opposite occurred with the pregnancy rate to FTAI on Day 10 (p < 0.01). There was no effect of progesterone source, GnRH analogue or their interaction on overall pregnancy rates (64.9%). Progesterone treatment of heifers during an Ovsynch protocol resulted in a larger pre-ovulatory follicle in beef heifers. Progesterone content of intravaginal devices in synchronization protocols is important for the timing of AI, as the use of low-progesterone devices can shorten the interval to oestrus.
authors: AgResearch Limited, Invermay Agricultural Centre, Mosgiel, New Zealand. marcelo.martinez@agresearch.co.nz
authors: M F
authors: MF
authors: Martinez
authors: G
authors: G
authors: de Nava
authors: K J
authors: KJ
authors: Demmers
authors: D
authors: D
authors: Tutt
authors: M
authors: M
authors: Rodriguez Sabarrós
authors: B
authors: B
authors: Smaill
authors: M
authors: M
authors: Corti
authors: J
authors: J
authors: Juengel
mesh_terms: D000282:Administration, Intravaginal; D000818:Animals; D002064:Buserelin / Q000008:administration & dosage / Q000494:pharmacology; D002417:Cattle; D004958:Estradiol / Q000008:administration & dosage / Q000031:analogs & derivatives / Q000494:pharmacology; D004973:Estrus Synchronization / Q000379:methods*; D005260:Female; D007315:Insemination, Artificial / Q000662:veterinary*; D008525:Medroxyprogesterone / Q000008:administration & dosage / Q000494:pharmacology; D009842:Oligopeptides / Q000008:administration & dosage / Q000494:pharmacology; D011247:Pregnancy; D011374:Progesterone / Q000008:administration & dosage* / Q000494:pharmacology*
chemical_list: D009842:Oligopeptides; C533053:lecirelin; C074283:estradiol 3-benzoate; D011374:Progesterone; D004958:Estradiol; D008525:Medroxyprogesterone; D002064:Buserelin