Estratégias de manejo para aumentar a eficiência reprodutiva de fêmeas equinas da raça Mangalarga Marchador

Abstract

In the experiment 01 the purpose of this work was to optimize the reproductive potential of embryos donors (n = 5) of the Mangalarga Marchador breed submitted to an annual program of embryo production. In Southeast Region, Três Rios – RJ, the embryo recovery was performed between November/2005 and April/2006 and in Northeast Region from May to December/2006. The donors and recipients mares were monitored every other day by rectal and ultrasonographic examinations until they ovulated. On the eight days after ovulation the uteri of the donors were flushed with lactated Ringer’s solution and the embryos were immediately transferred to the recipients mares, which were examined eight days later to confirm the pregnancy. Eighty flushes provided 69 (86.3%) embryos with 37 (53.6%) pregnancies, result that showed the possibility to produce embryo over the whole year. The donors produced, in the Southeast Region, 7.8±1.4 embryos and 4.0±1.0 pregnancies and in Northeast Region, 6.0±2.0 embryos and 3.4±1.1 pregnancies. With this alternative in the program was possible to obtain additionally 6.0 embryos and 3.4 pregnancies. The results allow recommending the use of embryo donors over the whole year because provide higher number of birth, as well as accelerate the genetic breed horse development. In the experiment 02 The purpose of this study was to compare the effectiveness of techniques such as artificial insemination and embryo transfer, with the indices of embryonic death occurred in the conduct of these techniques, during the years of 2003 to 2006. Mares were used racial mangalarga marchador aged ranging between 05 and15 years. The mares were divided into two groups: Artificial Insemination (Group 01) and transfer of embryos (Group 02). Both groups were monitoring the cycle estral on alternate days with the help of ultra-sonography, being inseminated by ovulation from the detection of the beginning. In animals belonging to the group 01 the diagnosis of pregnancy was performed in the 15-day post - ovulation with monitoring in the days 30, 45 and 60 of gestation. In Group 02 on the eighth day post - ovulation was held the harvesting of embryo by open method, using the solution with lactated Ringer, washed positive for embryo were inoculated in receiving in good conditions that have their reproductive cycle estral controlled until ovulation. Only the embryos were inoculated ranked from 01 to 03. In this group the diagnosis of pregnancy was performed in 05 ° day after inovulação in receiving and monitoring was performed on days 15, 30, 45 and 60 of gestation. Between the years of 2003 and 2006 the group 01 received half year around 11.6%, while in group 02 to annual average was around 12%. The results suggest that allows no interference from the implementation of the techniques in rates of embryonic loss. In the experiment 03 This aim of this study was to diagnostic previously the gender of equine fetuses (n = 157) of Mangalarga Marchador by ultra-sound, identifying the final position of the genital tubercle or viewing the anatomical structures of external genitalia. The exams were realized in alternate days, by via transrectal, between 58º and 69º, as well as between 90º and 150º dayof pregnancy. The mares were artificially inseminated on the ovulation day and this day was considered as pregnancy day (Day 0). The pregnancy diagnosis was performed on the 15º day after ovulation. There was not observed difference (P > 0. 05) on the fetal sexing accuracy between male (95.6%) and female fetuse (91.4%). However, was verified that the accuracy of the exam realized takin into consideration the genital tubercle (90.1%) was lower (P < 0. 05) than exam made takin into consideration the genital structures (93.7%). The results allow to conclude that the ultrasound is a suitable method to early diagnostic the fetal sex by identification of final position of genital tubercle, especially by visualization of anatomical structures of external genitalia.