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Effect of Time of Artificial Insemination on Pregnancy Rates, Calving Rates, Pregnancy Loss, and Gender Ratio After Synchronization of Ovulation in Lactating Dairy Cows

Richard Pursley, J. ; Silcox, Roy W. ; Wiltbank, Milo C.

Journal of dairy science, 1998-08, Vol.81 (8), p.2139-2144 [Periódico revisado por pares]

Savoy, IL: Elsevier Inc

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Título:
Effect of Time of Artificial Insemination on Pregnancy Rates, Calving Rates, Pregnancy Loss, and Gender Ratio After Synchronization of Ovulation in Lactating Dairy Cows
Autor: Richard Pursley, J. ; Silcox, Roy W. ; Wiltbank, Milo C.
Assuntos: Abortion, Veterinary - epidemiology ; Animal productions ; Animals ; ARTIFICIAL INSEMINATION ; Biological and medical sciences ; Cattle - physiology ; CHOIX DE LA DATE ; DAIRY COWS ; ELECCION DE LA EPOCA ; EMBRYO MORTALITY ; Female ; Fundamental and applied biological sciences. Psychology ; gender ratio ; GESTATION MULTIPLE ; GNRH ; GONADOLIBERINE ; GONADOTROPIN RELEASING HORMONE ; HORMONA LIBERADORA DE GONADOTROPINA ; INSEMINACION ARTIFICIAL ; INSEMINATION ARTIFICIELLE ; Insemination, Artificial - veterinary ; Lactation - physiology ; LACTATION NUMBER ; Male ; MORTALIDAD ; MORTALITE ; MORTALITY ; MULTIPLE BIRTHS ; NUMERO DE LACTACION ; NUMERO DE LACTATION ; OESTRUS SYNCHRONIZATION ; Ovulation ; Parity ; PARTOS MULTIPLES ; PERFORMANCE DE REPRODUCTION ; Pregnancy ; pregnancy rate ; PROPORCION DE LOS SEXOS ; REPRODUCTIVE PERFORMANCE ; REPRODUCTIVIDAD ; SEX RATIO ; SINCRONIZACION DEL CELO ; SYNCHRONISATION DE L'OESTRUS ; synchronization of ovulation ; Terrestrial animal productions ; Time Factors ; TIMING ; TWINNING ; VACAS LECHERAS ; VACHE LAITIERE ; Vertebrates
É parte de: Journal of dairy science, 1998-08, Vol.81 (8), p.2139-2144
Notas: 1999001637
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Descrição: In order to assess the optimal time of artificial insemination (AI) in relation to ovulation, lactating dairy cows (n = 732) from herds with rolling herd averages of 9980 to 11,800kg from three milkings per day were randomly assigned to five groups by stage of lactation and parity. Ovulation was synchronized by administration of GnRH followed 7 d later with PGF2α followed 2 d later with a second treatment with GnRH. Cows were inseminated at 0, 8, 16, 24, or 32h after the second injection of GnRH (ovulation occurs between 24 and 32h after GnRH). Pregnancy diagnoses were performed by ultrasound at 25 to 35 d post-AI. Pregnancy rates per AI were similar for the groups inseminated at 0, 8, 16, and 24h and lower for the group inseminated at 32h. A significant quadratic effect of treatment suggests that the middle time periods (8, 16, and 24h) may produce the greatest pregnancy rate per AI. However, the group inseminated at 0h had lowest pregnancy loss, and the group inseminated at 32h tended to have the greatest pregnancy loss compared with that of the other groups. The calving rate was similar between the groups inseminated at 0, 8, 16, and 24h and lower in the group inseminated at 32h. The time of AI also appeared to affect gender of calf: cows bred at 0 and 32h having a higher percentage of female offspring. In conclusion, there appears to be substantial flexibility in the time of AI after the second injection of GnRH, and lower reproductive rates were observed only when AI was after the time of ovulation.
Editor: Savoy, IL: Elsevier Inc
Idioma: Inglês

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Effect of Time of Artificial Insemination on Pregnancy Rates, Calving Rates, Pregnancy Loss, and Gender Ratio After Synchronization of Ovulation in Lactating Dairy Cows

Richard Pursley, J. ; Silcox, Roy W. ; Wiltbank, Milo C.

Savoy, IL: Elsevier Inc

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