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(Reference retrieved automatically from SciELO through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Estrus synchronization and follicular dynamics of Crioulo mares by norgestomet, melengestrol acetate and altrenogest treatments

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Author(s):
Henry Berger de ALMEIDA [1] ; Wilson Gonçalves VIANA [2] ; Rubens Paes de ARRUDA [3] ; Cláudio Alvarenga de OLIVEIRA [4]
Total Authors: 4
Affiliation:
[1] Universidade de São Paulo. Faculdade de Medicina Veterinária e Zootecnia. Departamento de Reprodução Animal
[2] Universidade de São Paulo. Faculdade de Medicina Veterinária e Zootecnia. Departamento de Reprodução Animal
[3] Universidade de São Paulo. Faculdade de Medicina Veterinária e Zootecnia. Departamento de Reprodução Animal
[4] Universidade de São Paulo. Faculdade de Medicina Veterinária e Zootecnia. Departamento de Reprodução Animal
Total Affiliations: 4
Document type: Journal article
Source: Brazilian Journal of Veterinary Research and Animal Science; v. 38, n. 6, p. 267-272, 2001-00-00.
Abstract

21 Crioulo mares on reproductive age were grouped into 3 groups (I, II e III) with 7 animals each; group I was treated with unique 3 mg norgestomet + 5 mg estradiol valerate intramuscular injection and a subcutaneous implant of norgestomet during 9 days; group II received unique 5 mg of 17-beta estradiol intramuscular injection and 0,5 mg of melengestrol acetate given orally during 9 days; group III consisted on mares given 0,045 mg/kg altrenogest orally during 9 days. At progestogen treatment removal (9th. day), all mares from the 3 groups received luteolytic dose of luprosteol and 3.000 UI of hCG when dominant follicle was ultrasonographically detected in ovulatory conditions . All mares were daily evaluated by rectal palpation and ultrasound examination for retrospectively measurement of the largest and second largest follicles, and mated by tested stallions closed to ovulation. Follicular development was not observed on group II (MGA). Considering 5 days post PGF2a-analogue administration, synchronization rates for groups I and III were, respectively, 85.71% and 66.70% (p > 0.05). Porcentage of oestrus supression for these groups were, respectively, 85.71% and 100.00% (p > 0.05). Pregnancy rate was not significantly different between the two groups (I, 100% and II, 85.71%; p > 0.05). Results were based on mares showing response to the synchronization regimen. PGF2alpha-oestrus, PGF2alpha-hCG, hCG-ovulation and PGF2alpha-ovulation intervals for groups I and III were 4.5 ± 0.80 and 4.2 ± 0.8 (p > 0.05), 8.0 ± 1.41 and 6.17 ± 0.6 (p > 0.05), 1.5 ± 0.22 and 2.28 ± 0.28 (p > 0.05) and 9,8 ± 1,02 and 8,6 ± 1,32 (p > 0.05) days respectively. The results prove the eficiency of oestrus synchronization regimens by norgestomet implant and oral administration of altrenogest, with tendency to higher synchronization rate to norgestomet system, although no significantly diferences were observed concerning to reproductive parameters and follicular dynamics data, with exception to the minor largest diameter of dominant follicles and ocurrence of only one major wave for supressed cycles by progestogen-estradiol regimen. (AU)