Altering conception of dairy cattle by gonadotropin-releasing hormone preceding luteolysis induced by prostaglandin F2 alpha

The objective of these experiments was to determine the effect on fertility of GnRH when used in conjunction with one or two injections of PGF2 alpha. In Experiment 1, GnRH was administered 7 d before the second of two injections of PGF2 alpha (14 d apart). The control group received two injections...

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Bibliographic Details
Published in:Journal of dairy science 1996-03, Vol.79 (3), p.402-410
Main Authors: Stevenson, J.S. (Kansas State University, Manhattan.), Kobayashi, Y, Shipka, M.P, Rauchholz, K.C
Format: Article
Language:English
Subjects:
Animal productions
Animals
Biological and medical sciences
Cattle
CICLO ESTRAL
CONDICION CORPORAL
Corpus Luteum - drug effects
CYCLE OESTRAL
Dinoprost - pharmacology
ELIMINACION
Estrus Detection
ETAT CORPOREL
Female
FEMELLE
FERTILIDAD
FERTILITE
Fertilization
Fundamental and applied biological sciences. Psychology
GONADOLIBERINE
Gonadotropin-Releasing Hormone - pharmacology
HEMBRA
HORMONA LIBERADORA DE GONADOTROPINA
INSEMINACION ARTIFICIAL
INSEMINATION ARTIFICIELLE
Insemination, Artificial - veterinary
NUMERO DE LACTACION
NUMERO DE LACTATION
Ovulation Induction
PERFORMANCE DE REPRODUCTION
Pregnancy
PROGESTERONA
PROGESTERONE
PROSTAGLANDINAS
PROSTAGLANDINE
PUERPERIO
PUERPERIUM
REFORME DES ANIMAUX
REPRODUCTIVIDAD
SERUM SANGUIN
SINCRONIZACION
SUERO SANGUINEO
SYNCHRONISATION
Terrestrial animal productions
VACAS LECHERAS
VACHE LAITIERE
Vertebrates
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Summary:The objective of these experiments was to determine the effect on fertility of GnRH when used in conjunction with one or two injections of PGF2 alpha. In Experiment 1, GnRH was administered 7 d before the second of two injections of PGF2 alpha (14 d apart). The control group received two injections of PGF2 alpha without GnRH. Conception was reduced from 63.5% for 74 controls to 48.7% for the 79 heifers and cows that had been treated with GnRH, but estrus detection and pregnancy rates were similar. In Experiment 2, 85 heifers and cows received GnRH at a random stage of the estrous cycle, followed in 7 d by PGF2 alpha. Thirty to 32 h after PGF2 alpha, a second dose of GnRH was given to induce ovulation of the preovulatory follicle, followed by one fixed-time insemination 18 to 19 h later (treatment designated as GnRH, PGF2 alpha, and GnRH). Controls (n = 85) were given PGF2 alpha and inseminated at estrus. Although conception rate was not different, one fixed-time insemination after the GnRH, PGF2 alpha, and GnRH treatment tended (35.3%) to reduce fertility compared with effects of the control (47.1%). It is unclear how an injection of GnRH during the intervening week between two injections of PGF2 alpha reduced fertility in Experiment 1. However, in Experiment 2, when GnRH was given 7 d before one injection of PGF2 alpha and when ovulation was induced with a second GnRH injection, one fixed-time insemination seemed to produce acceptable fertility in dairy cows but probably less than that when inseminations were based on detected estrus
ISSN:0022-0302
1525-3198
DOI:10.3168/jds.S0022-0302(96)76379-8