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Title in English Authors
The effect of GnRH after insemination on progesterone concentrations and conception rates in repeat-breeding Holstein cows under hest stress conditions Jorge Enrique Cruz Velázquez, Carlos Alejandro Elizondo Vázquez, Raúl Ulloa Arvizu, Ilda
Graciela Fernández García
Abstract Link of the article or author site's
The purpose of this research was to evaluate the response to the administration of gonadorelin (GnRH) on days 5 and 11 postartificial
insemination (PAI) on plasma progesterone concentrations and conception rates in repeat-breeding Holstein cows,
under heat stress conditions. Three treatment groups were set at random: T1) 100 μ,,g gonadorelin on d 5 PAI (GnRH-5, n=33),
T2) 100 μ,,g gonadorelin on d 11 (GnRH-11, n=34) PAI, T3) controls (no GnRH, n=34). Blood samples were collected on d 8,
11, 14, 17, 20, and 23 PAI for the determination of plasma progesterone (P4) concentrations by radio-immuno-assay (RIA).
Pregnancy was diagnosed by rectal palpation on d 43 ± 3 PAI. P4 concentrations were higher (P<0.05) in T1 (GnRH-5) on
d 11 PAI. Conception rates did not differ (P>0.05): T1 (GnRH-5) = 4/33, 12.1 %, T2 (GnRH-11) = 4/34, 11.8 %), T3 (Control)
= 5/34, 14.7 %). Cows were inseminated under a temperature/humidity index (THI) ≥,, 72 units, i.e.: heat stress. It was
concluded that the administration of GnRH on d 5 resulted in increased plasma progesterone concentrations, but this did not
improve conception rates in repeat-breeding Holstein cows under heat stress conditions.
Reference Format Date
Tec Pecu Mex 2009,47(1):107-115 Enero - Marzo 2009
Author Mail Type of Manuscript
Nota de investigación
Keywords Full Document
Vacas repetidoras, GnRH, Progesterona, Tasas de concepción, ITH, Estrés calórico,Repeat-Breeding, GnRH, Progesterone, Conception rates, Temperature/Humidity Index (THI), Heat stress Download PDF file

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