Avaliação dos parâmetros de gestação de éguas da raça Mangalarga Marchador

• Autor(a) principal: Matta, Manuela Pereira da
• Data de Publicação: 2013
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/5800
• topic: Gestação; Éguas; Mangalarga marchador; Gestation; Mares; Mangalarga marchador; CNPQ::CIENCIAS AGRARIAS::MEDICINA VETERINARIA::REPRODUCAO ANIMAL

The present study aimed to evaluate the pregnancy characteristics in recipient mares of Margalarga Marchador breed (MM).Sixty-two recipient mares aging 4 to 15 years were used. The animals were kept in an extensive pasture regimen, and five non-cyclic mares were treated with exogenous progesterone (P4) to receive embryos. The non-cyclic mares were treated with 10 ml of Medroxiprogesterone (150 mg) weekly until 100 days of pregnancy. Reproductive aspects were evaluated from the day of recipient mare selection to parturition through transrectal ultrasonography and palpation of reproductive system and by P4 and estradiol concentrations. Blood samples were collected on the following days: day of embryo transfer (DI) and on Days 13, 21, 30, 37, 45, 60, 75, 90, 120, 150, 180, 210, 240, 270, 300 and 330 after ovulation. Estradiol concentration was assayed only from Day 60 to Day 180. Transrectal ultrasonography was performed concomitant with the blood sampling to evaluate the characteristics of uterus, ovary, conceptus and placenta during pregnancy. The recipient mares were select based on the uterine tonus, cervical tonus, uterine echography, uterine edema, corpus luteum diameter, and dominant follicle diameter. Each recipient received a score in accordance with the reported characteristics. Embryos were evaluated and classified according the stage and quality of development before their transfer. In addition, during the ultrasonography evaluation uterine and ovary changes were detected and recorded. The characteristics evaluated were: presence of fluid and endometrial; number and size of corpora lutea; occurrence of ovulatory and anovulatory follicles; formation of accessory corpora lutea; and thickness of uterus-placenta junction (JUP). In regard the conceptus, was measured the size of embryonic vesicle, the crown-rump length (CR-CD); thoracic diameter (DT) and diameter of fetal eye socket (OC). The pregnancy length, day of embryo vesicle attachment in the uterus and occurrence of pregnancy loss (early or late conceptus death) were also evaluated. Embryos were collected between days 7 and 10 post- ovulation. Embryos were classified as grade I (80.5%), II (16.7%) and III (2.83%). For the development stage, embryos were classified as expanded blastocysts (68.0%), early blastocysts (20.80%) and compact morulas (8.43%). The growth of embryonic vesicle had a linear effect (P<0.0001), and was not affected by the embryo gender (P>0.05). The CR-CD, DT, and OC also had linear growth during pregnancy (P<0.0001). The number and area of corpora lutea (ACL) differed among the pregnancy periods evaluated (P<0.05). The ACL differed between days 13-30 postovulation and the day of embryo transfer (P<0.05). Concentration of P4 did not differ at the day of embryo transfer (P>0.05) in cyclic and non- cyclic mares, but differed during pregnancy among sampled days (P<0.05). A positive correlation was detected between ACL and P4 concentrations on Days 13, 60, 75 and 90 (P<0.05). The ACL also had a positive correlation (r = 0.32) with P4 concentration during pregnancy and a quadratic regression model was developed owing to predict the P4 level by ACL. For the comparison between cyclic and non-cyclic mares, P4 only differed between these two groups on Day 30 (P<0.05). Estradiol concentrations increased between Days 60 and 180 (P<0.05). All the pregnancy losses occurred in cyclic mares. The mean of pregnancy length was 334 days. In 61% of the mares, the pregnancy fixed in opposite uterine horn of the previous pregnancy regardless the corpus luteum side and 62.8 % of embryos fixed in the right uterine horn.