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Vertebrate reproductive science and technology
RESEARCH ARTICLE

410 ENHANCED OVARIAN RESPONSE TO LOW-DOSE TREATMENT WITH EQUINE PITUITARY EXTRACT IN MARES

A. M. Gimenes A , F. S. Ignacio A , A. L. N. Boff A , D. R. Bergfelt B and C. Meira A

A School of Veterinary Medicine and Animal Science, Sao Paulo State University - UNESP, Department of Animal Reproduction and Veterinary Radiology, Botucatu, São Paulo, Brazil;

B Repro Endo-To, Ashburn, VA, USA

Reproduction, Fertility and Development 22(1) 362-362 http://dx.doi.org/10.1071/RDv22n1Ab410
Published: 8 December 2009

Abstract

The present study aimed to evaluate the ovarian response to relatively low doses of equine pituitary extract (EPE) involving 40 estrous cycles in 15 horse mares. The mares were Mangalarga Marchador and ranged in age from 5 to 24 years. Transrectal ultrasonography was used at 24-h intervals to monitor follicular development and to detect ovulations (Day 0). On Day 8, all mares received 7.5 mg i.m. of dinoprost tromethamine (Lutalyse®, Pfizer, Paulínia, Brasil) and were randomly assigned to treatment and control groups as follows: Groups 1 and 2 (n = 8 cycles/group) received 6 mg of EPE i.m. twice daily, beginning when the largest follicle was 20 to 23 mm (Group 1) or regardless of follicle size on Day 8 (Group 2); Groups 3 and 4 (n = 8 cycles/group) received 8 mg of EPE i.m. twice daily, beginning when the largest follicle was 20 to 23 mm (Group 3) or regardless of follicle size on Day 8 (Group 4); Group 5 (control; n = 8 cycles) received saline i.m. starting on Day 8. Treatments with EPE or saline continued until the largest follicle reached ≥35 mm, at which time a single dose of hCG (2500 IU i.v. Vetecor®, Hertape Calier Saúde Animal S/A, Juatuba, Brasil) was given. Groups were compared using ANOVA and mean differences among groups were located with ScottKnott test. There was an effect of group (P < 0.05) for number of follicles >30 mm, ovulations, and days of treatment as indicated in the table. In conclusion, starting EPE treatment with 8 mg (16 mg day-1) when the largest follicle reached 20 to 23 mm (Group 3) was the most effective for enhancing the number of >30 mm follicles and ovulations with minimal days of treatment.

FAPESP and JM Farm for funding the project.


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