Estrous Synchronization Superovulation and Embryo Transfer Estrous Synchronization A management technique that makes use of hormones to control or reschedule the estrous cycle Hormones associated with reproduction LH & FSH Progesterone Estrogen Prostaglandin Why synchronize? Group females for parturition (calving interval)  Shorten breeding season  Reduce estrus detection  Advantages of implementing a synchronization program Calves produced early in season will wean heavier because they are older  Cows require 40-60 days to recover from calving before next breeding  – Cows that bred earlier have better chance of maintaining 365 d calving interval the next year Basis for Synchronization of Estrus  Manipulate life span of CL  Manipulate growth of follicles and timing of ovulation Synchronization Methods Method Tradename Utilization Gonadotropins Cystorelin Fertagyl Mature females Prostaglandins Estrumate Lutalyse Prostamate Cycling females Progestins MGA CIDR Pre-pubertal heifers Post-partum or Anestrous females Synchronization Methods Gonadotropins(GnRH protocols)  Naturally occurring hormone that stimulates the release of LH and FSH that stimulates follicular development  Protocols include Ovsynch and Cosynch Synchronization methods Prostaglandins – Naturally occurring hormone that causes regression of the CL (luteolysis) and decreases progesterone secretion which results in a return to estrus – Can expect estrus within two days following injection – Protocols include PGF one-shot method and PGF two-shot method Synchronization methods Progestins  Form of progesterone that extends the period of time progesterone is present and prevents animal from coming into heat  Protocols include MGA+prostaglandin and CIDR Synchronization methods: drug trade names and effectiveness Method Prostaglandins Progestins * Cattle Trade name Lutalyse* Estrumate* Prostamate* Equimate∞ MGA* CIDR* Regumate∞ ∞Equine Female “type” for drug effectiveness *Cycling cows or heifers ∞Cycling mares *Cycling cows or heifers *Anestrous cows or heifers ∞Mares ^Swine Synchronization methods: drug trade names and effectiveness Method Trade name Female “Type” for drug effectiveness Gonadotropin Releasing Hormones Cystorelin* Fertagyl* Ovuplant∞ *Postpartum cows *Anestrous cows ∞Cycling mares Placental Gonadotropins PG600^ ^Peri-pubertal gilts * Cattle ∞Equine ^Swine Cost $2.50/head One Injection of PGF  Advantages – Useful for detection of estrus in heifers and cows – Decreased drug cost – Limited animal handling  Limitations – 10-25% of females may not be detected in estrus during days 0 to 10 – Poor degree of synchrony on females that return to estrus – Must have CL – Length of estrus detection – Abortion