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RESEARCH ARTICLE
Contents Vol 20(3)

Miniature ponies: 1. Follicular, luteal and endometrial dynamics during the oestrous cycle

E. L. Gastal A D , A. P. Neves B , R. C. Mattos B , B. P. L. Petrucci B , M. O. Gastal C and O. J. Ginther A C
+ Author Affiliations
- Author Affiliations

A Department of Pathobiological Sciences, University of Wisconsin, Madison, WI 53706, USA.

B Department of Animal Medicine, Federal University of Rio Grande do Sul, Porto Alegre, RS, Brazil.

C Eutheria Foundation, Cross Plains, WI 53528, USA.

D Corresponding author. Email: egastal@svm.vetmed.wisc.edu

Reproduction, Fertility and Development 20(3) 376-385 https://doi.org/10.1071/RD07164
Submitted: 17 September 2007  Accepted: 17 December 2007   Published: 5 February 2008

Abstract

Follicular dynamics were studied during 12 interovulatory intervals (IOIs) and 36 preovulatory periods in Miniature mares. The percentage of IOIs with the following follicle events was: ovulatory wave with only one follicle ≥10 mm (55%), diameter deviation similar to previous reports in larger mares (25%) and minor waves emerging before or after the ovulatory wave (55%). Follicle data were compared among Miniature ponies, large ponies and Breton horses (n = 12 IOIs per breed). The IOI was longer (P < 0.001) in Miniature ponies (23.3 ± 0.9 days) and in large ponies (23.9 ± 0.5 days) than in Breton horses (20.3 ± 0.7 days). The Miniature ponies had fewer (P < 0.0001) growing follicles ≥10 mm per ovulatory wave (1.5 ± 0.3) and more (P < 0.0004) ovulatory waves (6/11) with only one follicle ≥10 mm than large ponies (9.8 ± 0.8 and 0/12) and horses (5.8 ± 0.9 and 0/12). Maximum diameter of the preovulatory follicle was smaller (P < 0.003) in the Miniature ponies (38.3 ± 0.7 mm) than in the horses (44.5 ± 1.4 mm), but the difference between breeds was slight (6%) compared with the difference in bodyweight (65%). Considering the small number of follicles per ovulatory wave, Miniature mares are a potential model for comparative studies in folliculogenesis within and among species.

Additional keywords: corpus luteum, endometrial echotexture, follicles, ultrasound.


Acknowledgements

This research (Project MP1-APN-04) was supported by the Federal University of Rio Grande do Sul (Porto Alegre, RS, Brazil), PRONEX CNPq/FAPERGS, and the Eutheria Foundation, Inc., Cross Plains, Wisconsin. The authors thank Mr. Santo Sérgio Feoli, Cabanha Morada das Pôneis, for use of the mares; Alisul Alimentos S. A., Brazil for a gift of the commercial ration; and Dee Cooper for assistance with the figures. R. C. Mattos thanks the CNPq for a Research Fellowship. The authors declare that there is no conflict of interest that would prejudice the impartiality of this scientific work.


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