Resposta folicular ovariana e produção oocitária de cabras submetidas a protocolos de estimulação ovariana

Abstract

The study aimed to evaluate the ovarian follicular response and the production of goat oocytes undergo ovarian stimulation protocols. There were two experimental stages 24 and 18 animals respectively randomized in a 2x2 factorial design, with assessment of the effects: duration of hormonal protocol (six or twelve days) and number of follicle stimulating hormone applications (FSH) (one or five doses). All animals received intravaginal sponges impregnated with 60mg of medroxyprogesterone acetate (MAP) over the period of six (short protocol) or twelve days (long protocol), applying 125μg cloprostenol, 72 hours before removal of the sponges. For ovarian stimulation was applied FSH 120mg single dose 36h before laparoscopic ovum pick-up (LOPU) or five doses (30/30; 20/20 and 20mg) in 12 hour intervals, with the last dose applied 36h before LOPU. In the first step, were performed serially ultrasound on day 0 (D0); D3/D8; D4/D9; D5/D6 and D10/D11, respectively, for the short and long protocols, for monitoring of ovarian response to hormonal treatments. In the second stage, the animals were subjected to LOPU for determining the number of follicles visualized and aspirates those from 2 to 7mm in diameter; number of cumulus oocyte complex (COCs) recovered; recovery rate; morphological classification of COCs (Grade 1, 2, 3 and 4) and the rate of viable COCs for use in vitro embryo production. In the first stage the data were evaluated by Generalized Linear Models and the second by analysis of variance at 5% probability. There was no effect of the factors and interaction (P> 0.05) for number of follicles in the evaluation of D0 and D3/D8. However, the evaluation D6/D11 (time of LOPU) was effect (P <0.05) the duration of the protocol factor for number of small follicles, with 1.05±0.62 in the short protocol and absence of these follicles in the long protocol. There was effect of the number of doses of FSH to the follicles of medium and large categories, with the largest number of medium follicles single dose (6.49±1.45) and large follicles (7.97±1.61) for multiple doses. There was no effect of the factors and interaction (P> 0.05) to the diameter of the large, medium and small follicles, except for assessment made at the fourth application of FSH in the protocols with five doses (D4 / D9) with effect of interaction for large follicles (P <0.05). In the second stage, there was no effects of factors or interaction (P> 0.05) for number of follicles visualized (16.9±8.01) and aspirates (12.2±5.6); number of recovered COCs (8.1±4.6); recovery rate (65.0±18.7%); morphological quality of COCs in grade 1 (4.3±4.4), grade 2 (2±1.5), grade 3 (1.2±1.1), grade 4 (0.4 ± 0.5) and COCs viable rate (92.1%). Four protocols were effective in stimulating ovarian response and oocyte production in goats, however, would be more suitable to use the short protocol (7 days) and application of a single dose of FSH, based on the largest number of medium follicles available for aspiration, in addition to the shorter time and more practical implementation.