Synchronization and Resynchronization of Ovulation and Timed Insemination in Lactating Dairy Cows and Heifers

dc.contributor.authorPeeler, Iris Dawnen
dc.contributor.committeechairNebel, Raymond L.en
dc.contributor.committeememberNickerson, Stephen C.en
dc.contributor.committeememberCassell, Bennet G.en
dc.contributor.committeememberPearson, Ronald E.en
dc.contributor.departmentDairy Scienceen
dc.description.abstractThis study was conducted to evaluate the efficacy of intravaginal progesterone (P4) inserts (CIDR) in synchronization protocols combined with timed artificial insemination (TAI) as related reproductive performance. In the first study, heifers were synchronized with CIDR inserts followed by TAI. Heifers in the estradiol cypionate (ECP) group were synchronized with a combination of ECP, CIDR, prostaglandin (PGF2α), and ECP (CIDR-ECP), while the gonadotropin-releasing hormone (GnRH) group was synchronized using a combination of ECP, CIDR, PGF2α, and GnRH (CIDR-GnRH). All heifers were bred at either 48, 56, or 72 hours (h) after CIDR removal. Overall pregnancy rate (PR) for synchronized heifers was 60.1%, and embryo survival rate (ESR) was 98%. Pregnancy rate for CIDR-ECP treated heifers was influenced by artificial insemination (AI) time. In conclusion, ECP or GnRH may be used effectively in a CIDR-based TAI program in heifers. In the second study, cows were synchronized with CIDR devices or Ovsynch. The CIDR group received a combination of ECP, CIDR, PGF2α, and GnRH, while the Ovsynch group was synchronized using a combination of GnRH and PGF2α. Cows were bred at either 0, 8, or 24 h after the final GnRH injection. Overall PR for first service was 30.5% with ESR of 82.8%. Overall resynchronization PR was 35.1% with an ESR of 84.8%. In conclusion, Ovsynch and CIDR-based protocols are equally effective in synchronizing ovulation in a TAI program and resulted in comparable PR.en
dc.description.degreeMaster of Scienceen
dc.publisherVirginia Techen
dc.rightsIn Copyrighten
dc.subjectreproductive performanceen
dc.subjecttimed artificial inseminationen
dc.subjectdairy cattleen
dc.titleSynchronization and Resynchronization of Ovulation and Timed Insemination in Lactating Dairy Cows and Heifersen
dc.typeThesisen Scienceen Polytechnic Institute and State Universityen of Scienceen


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