Reproductive Performance of Ewes after 5-Day Treatment with Intravaginal Inserts Containing Progesterone in Combination with Injection of Prostaglandin F2α

• Published in: Reproduction in domestic animals 2006-04, Vol.41 (2), p.142-148
• Main Authors: Dixon, AB, Knights, M, Pate, JL, Lewis, PE, Inskeep, EK
• Format: Article
• Language: English
• Subjects: Animal productions; Biological and medical sciences; Fundamental and applied biological sciences. Psychology; Mammalian reproduction. General aspects; Terrestrial animal productions; Vertebrates; Vertebrates: reproduction
• ISSN: 0936-6768; 1439-0531
• DOI: 10.1111/j.1439-0531.2006.00656.x

Contents Three experiments were conducted with a total of 1579 ewes to examine reproductive performance in response to synchronization of oestrus during the breeding season, using controlled internal drug releasing (CIDR‐G) inserts in regimens designed to provide high concentrations of circulating progesterone. In experiment 1, treatment with two CIDR‐G inserts for 12 days produced conception rate (79%) and prolificacy (1.9) to first service equivalent to breeding at natural oestrus (56% and 2.0, respectively). Pregnancy rates to two service periods were 90 and 79%, respectively. In experiments 2 and 3, progesterone was delivered by a single CIDR‐G insert for 5 days in combination with prostaglandin F2α (PGF2α; 5 mg i.m., twice, 3 h apart) the day before (experiment 2), or at insert removal (experiment 3). The combined treatments improved rates of synchronization of oestrus (p