Pico pré-ovulatório de LH em fêmeas Nelore (Bos taurus indicus) sincronizadas
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Data
2009
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Resumo
The aim of this work was to evaluate the
frequency of pulses and the amplitude of the preovulatory
peak of the luteinizing hormone (LH) in
Nellore heifers and cows submitted to a hormonal
protocol. In six females owning to each category
the following protocol was used: placement of the
norgestomet implant (NOR) and application of 2.0
mg of estradiol benzoate (EB) on day zero, with
retreat after eight days, followed by the application
of 0.5 mg of sodic cloprostenol. After 24 hours
(day nine) 1.0 mg of EB was used. The blood
sampling was initiated 27.00 hours after the
application of the second dose of EB, and repeated
every 15 minutes for a six hours period. Seric
levels of LH were detected by radioimmunoassay
method. In one heifer and in four cows the preovulatory
peak of LH was observed. In the heifer
the peak was verified in the first sampling, 27.00
hours after the ovulation induction. In the cows
this occurred on 28.20±0.55 hours after application
of EB. The maximum amplitude verified was 4.58±0.67 ng/ml. In the animals in which LH peak
was not observed, the average concentrations
were 0.90±0.03 ng/ml for the heifers and 0.86±0.03
ng/ml for the cows. It suggests that in the heifers
the pre-ovulatory peak of LH, probably, have
occurred more precociously than in the cows.
However, more studies about the LH peak moment
in bovine females with synchronized ovulation are
needed.
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Palavras-chave
Benzoato de estradiol, Bovinos, IATF, Progestágenos, Estradiol benzoate, Bovine, TAI, Progestins, Reproduction
Citação
FERRAZ, H. T.; OLIVEIRA FILHO, B. D.; GAMBARINI, M. L.; VIU, M. A. O.; LOPES, D. T.; SOUSA, A. P. F. Pico pré-ovulatório de LH em fêmeas Nelore (Bos taurus indicus) sincronizadas. Archivos de Zootecnia, Córdoba, v. 58, n. 224, p. 757-760, 2009.