Journal article
Time and Incidence of Ovulation and Conception Rates After Incorporating Estradiol Cypionate into a Timed Artificial Insemination Protocol
Journal of dairy science, Vol.89(2), pp.620-626
02/2006
Handle:
https://hdl.handle.net/2376/105880
PMID: 16428631
Abstract
Two experiments were conducted to determine the effect of estradiol cypionate (ECP), when incorporated into a conventional GnRH-PGF2α-GnRH timed artificial insemination protocol (Ovsynch), on systemic estradiol (E2), time and incidence of ovulation, luteal development, and conception rate in Holstein cows. Our objective was to determine if administration of 0.25mg of ECP at the time of the second GnRH injection would effectively synchronize ovulation and increase conception rate. In Experiment 1, lactating Holstein cows (n = 23; 58.7±1.2 d in milk) were synchronized with PGF2α (at d −10). Ten days later, Ovsynch was initiated with the administration of 100μg of GnRH (d 0) followed by PGF2α on d 7. On d 9, cows were assigned randomly to be treated with either GnRH + 0.25mg of ECP (OVS-ECP; n = 11) or GnRH and 1mL of cottonseed oil (OVS-C; n = 12). Ovarian activity was monitored by ultrasonography on d 0, 7, and 9. To determine the time of ovulation, ultrasound examinations were conducted at 12 and 20h posttreatment and then at least every 3h until either 36h posttreatment or ovulation was observed. Blood samples were collected on d 0, 7, 9, and 16 for progesterone analysis. Blood samples also were collected at the time of treatment (d 9, 0h) and at 6, 12, 20, and 28h for E2 analysis. Incidence of ovulation did not differ between treatments. Mean ovulation time relative to the second GnRH administration was similar between treatments. Serum progesterone concentration did not differ between treatments at any time. Serum E2 concentration was not different at the time of treatment (0h); however, mean E2 concentration was greater for the OVS-ECP group at 6 and 12h after treatment compared with OVS-C. In Experiment 2, lactating dairy cows (n = 333) in 3 commercial herds were randomly assigned to OVS-ECP (n = 169) or OVS-C (n = 164). Cows were inseminated 22 to 24h posttreatment. Conception rates did not differ between treatments. Estradiol cypionate treatment was successful in increasing serum E2 when administered at the time of the second dose of GnRH in the Ovsynch protocol. Conception rates, however, were not affected by treatment.
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Details
- Title
- Time and Incidence of Ovulation and Conception Rates After Incorporating Estradiol Cypionate into a Timed Artificial Insemination Protocol
- Creators
- C.B Sellars - Animal and Veterinary Science Department, University of Idaho, Moscow 83844J.C Dalton - Animal and Veterinary Science Department, University of Idaho, Moscow 83844R Manzo - Animal and Veterinary Science Department, University of Idaho, Moscow 83844J Day - Dairy Health Services, Jerome, ID 83338A Ahmadzadeh - Animal and Veterinary Science Department, University of Idaho, Moscow 83844
- Publication Details
- Journal of dairy science, Vol.89(2), pp.620-626
- Academic Unit
- UNKNOWN
- Publisher
- Elsevier Inc
- Identifiers
- 99900546839601842
- Language
- English
- Resource Type
- Journal article