In female cattle synthesis of prostaglandin F2 a (PGF2 a) endometrial, between days 15 and 19 of the estrous cycle, determines the functional and structural regression of the corpus luteum. During this period, recognized as critical to the establishment of pregnancy, the conceptus (embryo and associated membranes) must competently produce molecules that interact with the endometrium by inhibiting the synthesis of PGF2 a. It has been reported that the inability of the fetus to send anti-luteolytic signals appropriate to the endometrium determines embryonic mortality by more than 20% of the females, a condition featuring Representative economic losses in livestock. Studies have reported the possibility of restricting the ability of synthesis of PGF2 a in the endometrium through manipulations in the dietary ingredients. Administration of compounds rich in linoleic acid in the uterus provides a differentiated selection of "pool" of lipids, providing a smaller amount of arachidonic acid event that limits their ability to synthesize PGF2 a. To date, the effectiveness of supplemental fat in improving reproductive performance in cows presents contradictory results and the vast majority of studies were conducted with dairy cows. Also, when the increase in the conception rate was recognized mechanisms by which such biological effect was caused been little studied. Among the sources likely to be fed to cattle linoleic acid is included with an economically viable alternative, sunflower seed (Helianthus annuus L.). Thus, since 2007 this research group investigates the effects of supplementation with sunflower seed in conception rates of bovine females. In previous studies by this group (Peres et al., 2008), administration of sunflower seed in Nelore (n = 212) cows for 22 days from the day of artificial insemination (TAI), had a greater conception rate compared to unsupplemented cows (66.7% vs. 46.3%;. p = 0.02). In a second study by this group, SOUZA et al. (2013) found that supplementation provided to the same recipients (n = 217) of embryos produced in vitro undergoing Embryo Transfer in Fixed Time (FTET) resulted in a higher conception rate in Sunflower Group compared to Control [55.66% (59/106) vs. 36.94% (41/111) respectively; p <0.01]. Thus, it is concluded that such supplementation causes an increase in conception rate of approximately 19% when associated with TAI and FTET programs. The cost of such supplementation for a period of 22 days is approximately £ 18.00, which determines a great cost / benefit of such programs. Given these results, supplementation used is an excellent biological model study to investigate the effects of fat on increasing conception rate. The hypothesis of this study is that supplementation with sunflower seed determines changes in the profile of proteins that constitute the uterine microenvironment froma to favor maternal-fetal recognition. Thus, the present study has the general objective to compare the protein profile of the uterine microenvironment on the 7th, 16th and 22nd day after withdrawal of progesterone implant, by using the technique of two-dimensional electrophoresis in supplemented Nellore cows with or without seed sunflower.
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