Ovarian and endocriny dinamyc of mares with different ages / Dinâmica ovariana e endócrina de éguas em diferentes idades

AUTOR(ES)
DATA DE PUBLICAÇÃO

2007

RESUMO

The present study was divided in tree experiments, led with the intention of characterizing the reproductive hormones and the population follicular close to the ovulation in mares of different ages, young (4 to 6 years), middle (10 to 14 years) and old mares (above 18 years). Samples of blood were collected daily and the analyzed hormones were FSH, LH, progesterone and estradiol. Number of follicles was determined by grouping the follicles diameters into the following categories: a) 2-5 mm, b) 5,1-10 mm, c) 10,1-15 mm, d) 15,1-20 mm, e) 20,1-25 mm, and f) = 25,1 mm. Differences found among age groups include: great concentrations of LH around the ovulation in more 18 years old pony mares and more rapid growth of the largest follicles in the youngest mares (5-6 years). Experiment 2, the follicular and hormonal aspects of diameter deviation and development of one dominant (= 28 mm) follicle (1DF) versus two dominant follicles (2DF) was studied in 32 follicular waves in mares. Follicles were ranked each day as F1 (largest) to F3. The beginning of deviation was designated Day 0 and preceded the first increase in the differences in diameter between F1 and F2 in the 1DF group and between a combination of F1 and F2 versus F3 in the 2DF group, 1DF and 2DF developed in 21 (66%) and 11 (34%) waves, respectively. The similarities on Day 0 in the characteristics of 1DF and 2DF waves despite the differences in the declining portions of the FSH profiles indicated that a specific day of the FSH decline or a specific concentration were not factors in initiating deviation. Results did not indicate a hormonal basis for the development of 2DF. Experiment 3, Repeatability within mares was based on a significant positive correlation between the two IOIs. The following end points were correlated significantly: 1) length of the interval between ovulations (r = +0.67) and between ovulation and the beginning of follicle deviation (r = +0.58); 2) diameter of the preovulatory follicle on Days - to -1 (average, r = +0.49); 3) number of follicles in diameter classes of 2 to 5 mm (r = +0.65 average of the daily correlations for the IOI; significant individual daily correlations on 22/23 days), 5.1 to 10 mm (r = +0.49; 18/23 days), 10.1 to 15 mm (r = +0.40; 12/23 days), and 15.1 to 20 mm (r = +0.42; 12/23 days); and FSH (r = +0.55; 18/23 days) and LH concentrations (r = +0.59; 22/23 days). The repeatability for number of follicles was greatest in the smallest diameter class (2 to 5 mm). Results demonstrated measurable repeatability within mares for several end points between consecutive IOIs. More studies are necessary to determine the effect of age in the reproductive activity in mares pony above 24 years of age.

ASSUNTO(S)

equine gonadotropinas eqüinos ciclo estral estrous cycle producao animal gonadotropins

ACESSO AO ARTIGO

Documentos Relacionados