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Maintenance of pregnancy in postpartum beef cows that have short-lived corpora lutea.
- Source :
-
Journal of animal science [J Anim Sci] 1992 Dec; Vol. 70 (12), pp. 3831-7. - Publication Year :
- 1992
-
Abstract
- The first two experiments examined the role of the uterus in low pregnancy rates of beef cows induced to ovulate by early weaning. At 20 to 25 d postpartum, one-half of the cows in Exp. 1 and 2 received a s.c. implant containing 6 mg of norgestomet (NOR) for 9 d (NOR-pretreated) and the remaining cows were untreated controls (CON). Lengths of first postpartum luteal phase after weaning of calves at d 7 after implant insertion were expected to be normal in NOR-pretreated and short in CON cows. In Exp. 1, cows of both groups received an implant containing 3 mg of NOR at d 4 after first estrus and a silastic implant with 15 or 25 mg of NOR at d 7 after first estrus. At 7 d after first estrus, two embryos were transferred into the uterus of each cow and pregnancy was diagnosed by ultrasonography at d 35. Blood samples were collected daily from onset of treatment to d 8 after estrus and then every other day to d 24. Only 4 of 22 cows were pregnant at d 35, concentrations of estradiol (E2) were elevated after luteolysis, and large follicles were present at d 35. In Exp. 2, all cows were injected with 100 mg of progesterone (P4) twice daily from d 4 to 35 after first estrus. Embryos were transferred, pregnancy was diagnosed, and blood samples were collected as in Exp. 1, except blood sampling was continued to d 34.(ABSTRACT TRUNCATED AT 250 WORDS)
- Subjects :
- Animals
Drug Implants
Embryo Transfer veterinary
Estradiol blood
Female
Luteal Phase physiology
Ovarian Follicle diagnostic imaging
Ovarian Follicle physiology
Postpartum Period physiology
Pregnancy
Pregnancy Outcome
Pregnancy, Animal physiology
Pregnenediones administration & dosage
Progesterone blood
Progesterone Congeners administration & dosage
Progesterone Congeners pharmacology
Random Allocation
Ultrasonography
Uterus physiology
Cattle physiology
Luteal Phase drug effects
Postpartum Period drug effects
Pregnancy, Animal drug effects
Pregnenediones pharmacology
Subjects
Details
- Language :
- English
- ISSN :
- 0021-8812
- Volume :
- 70
- Issue :
- 12
- Database :
- MEDLINE
- Journal :
- Journal of animal science
- Publication Type :
- Academic Journal
- Accession number :
- 1474021
- Full Text :
- https://doi.org/10.2527/1992.70123831x