Recent advances in ovulation synchronization and superovulation in ...

Abstracts. II International Symposium on Animal Biology of Reproduction, Nov. 19-22, 2008, São Paulo, SP, Brazil.
Progesterone profile secretion by Corpus luteum formed after follicular aspiration in mares
F.D. Mozzaquatro 1 , J.P. Verstegen 2 , R.H. Douglas 3 , M.H.T. Troedsson 2 , F.D. De la Corte 1 ,
M.I.B. Rubin 1 , C.A.M. Silva 1
1 Laboratory of Animal Embryology, Department Large Animal Clinics, Federal University of Santa Maria, Santa Maria/RS, Brazil;
2 College of Veterinary Medicine, University of Florida, Gainesville, FL 32618, USA; 3 B.E.T. Laboratories University of Kentucky
Coldstream Research Campus 1501, Lexington, KY, USA.
Introduction
Follicular aspiration has been used to study follicular dynamics and ovulation synchronization in animals. This study
aimed to evaluate the development of the Corpus luteum (CL) following follicular aspiration in mares. Luteal development
was determined by measuring serum concentrations of progesterone (P 4), and by a subjective characterization of the CL.
Materials and Methods
Crossbreed mares (n = 26) from 5 to 22 years of age, weighing 350 to 500kg and kept on pasture, were used for follicular
aspiration. Ovarian activity was accessed by the use of transrectal examination. Mares with follicles ≥25 mm (regardless
the oestrus cycle status) were assigned to groups according to follicular diameter: 25-29 mm; 30-35 mm and >35 mm.
Transvaginal follicular aspiration (1) was performed in all follicles ≥10 mm. Echographic images of each follicle and
structures at 4 days after aspiration were subjectively evaluated, considering the echographic image (Fig. 1). Blood
samples were collected daily starting immediately before (D0) and until 8 days after aspiration (D8), and stored at -20°C
for progesterone radioimmuneassay (RIA) evaluation. Linear regression analysis was used to establish the curve of
progesterone production. Qui-square test was used to verify the luteinization rates while Kruskal-Wallis to analyze
whether the echographic score was a valid method to indicate the functionality of the CL.
Results and Discussion
The average diameter and the number of aspirated follicles were 26.3 mm ± 1.38 (n = 7); 32.7 mm ± 1.28 (n = 8) and 43.2 ±
5.40 mm (n = 11) for the groups with diameters 25-29 mm; 30-35 mm and >35mm, respectively. During the aspiration, the fluid
flow was observed until the moment the follicle collapsed. No secondary ovulations were detected on transrectal ultrasonography
during the first 8 days after ovulation. The evaluation of luteal activity was based on echographic patterns in the presence of a
desirable P 4 production. The luteinization rate based on echographic characterization was highly significant (P < 0.0001), proving
that the US evaluation was valid method for CL classification. Corpora lutea classified as CL 1 and CL 2 had declining
concentrations of P 4 at a rate of 0.25 ng/mL/day (P = 0.03) and 0.14ng/mL/day (P = 0.2), respectively. In the mares with CL 3,
the P 4 concentration increased (0.61 ng/mL/day; P < 0.0001). This pattern is not different from those reported in mares with
spontaneous ovulation. It was concluded that the echographic score was a practical and efficient method to confirm luteinization.
Mares that had an echographic score of P 4 “CL 3” after aspiration might be suitable as recipient mares for embryo transfer.
Progesterone concentration
(ng/mL)
8
6
4
2
0
CL 1
0 1 2 3 4 5 6 7 8
days after follicular aspiration
Progesterone concentration
(ng/mL)
10
8
6
4
2
0
Anim. Reprod., v.6, n.1, p.229, Jan./Mar. 2009 229
CL 2
0 1 2 3 4 5 6 7 8
days after follicular aspiration
Progesterone concentration
(ng/mL)
6
4
2
0
CL 3
0 1 2 3 4 5 6 7 8
days after follicular aspiration
Figure 1. Corpus luteum (CL) classification in crossbreed mares according to ultrasonographic pattern at the 4 th day afterr follicular
aspiration (D0 = Follicular aspiration day). (A) CL 1– No CL visualization until the 4 th day after aspiration; (B) CL 2– Luteal structure
formed, however not much evident and with low echogenicity (see blue arrows). (C) CL 3– Image compatible with the CL (luteal
structure with high echogenicity, see white arrows).
References
(1) Hayna JT, Madill S, Troedsson MHT. 2004. The effect of transvaginal follicular aspiration on Corpus luteum
formation in mares. In: 6 th International Symposium on Equine Embryo Transfer. RJ, Brazil. Havemeyer Foundation
Workshop. pp. 35.
Support: Capes Funding.
A
A
E-mail:mararubin90@yahoo.com.br
B C