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J Vet Sci. 2006 Dec;7(4):387-390 |
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Alternative low doses and routes of administering a prostaglandin F2α analogue to induce luteolysis in Nelore cows
Cezinande Meira*, Valsair Matos Pessoa, João Carlos Pinheiro Ferreira, Gustavo Henrique M. Araujo, Marilu M. Gioso, Sony Dimas Bicudo, Eunice Oba, Cassia Orlandi |
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Department of Animal Reproduction and Veterinary Radiology, School of Veterinary Medicine and Animal Science, Sao Paulo State University, Botucatu, Sao Paulo 18618-000, Brazil. meira@fmvz.unesp.br |
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The present study was conducted in order to verify the
efficacy of lower doses and alternative routes of a
prostaglandin F2α analogue, luprostiol (PGF), for the
induction of luteolysis and the precipitation of estrus in
nonlactating Nelore cows (Bos taurus indicus). A
conventional dose (15 mg) of PGF was compared to doses
lower than the conventional dose, which ranges from 10 to
50%, that were administered intramuscularly (IM),
intravulvosubmucosally (IVSM), or in the Bai-hui
acupuncture site located within the lumbosacral area. The
cows were administered PGF 8 day after estrus in the
presence of a corpus luteum, and randomly assigned to
the following groups: G1 (positive control), 15 mg, IM (n
= 23); G2, 7.5 mg, IM (n = 23); G3, 3.75 mg, IM (n = 24);
G4, 7.5 mg, IVSM (n = 25); G5, 3.75 mg, Bai-hui acupoint
(n = 24); and G6, 1.5 mg, Bai-hui acupoint (n = 25). The
results indicated that 50% of a conventional dose of PGF
(7.5 mg) resulted in a complete luteal regression (plasma
progesterone <1 ng/ml) at Hour 48, and hastened estrus,
regardless of whether or not PGF was administered IM or
IVSM. Comparatively, 10 or 25% of the conventional
dose, even when administered to the Bai-hui acupoint,
resulted in an initial reduction in the concentration of
progesterone at Hour 24, followed by an increase observed
at Hour 48. In conclusion, 25% of a conventional PGF
dose administered via the Bai-hui acupoint proved
inadequate to induce a complete luteal regression,
whereas 50% of a conventional dose administered IM or
IVSM was found to be the minimal dose required to
induce effectively a complete luteal regression, and to
precipitate the onset of estrus in nonlactating Nelore cows.
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