The embryonic mortality between 15 and 19 days of pregnancy in cattle due to the increase in the release of endometrial PGF2a, resulting in regression of the corpus luteum. The synthesis of PGF2a can be inhibited in animals supplemented with linoleic acid-rich compounds, among them a sunflower seed. In a previous study (Peres et al., 2008), Nellore cows supplemented with sunflower seed for 22 days from the TAI had a higher conception rate (66.7% vs. 46.3%, p = 0.02) . In a second study by this group, SOUZA et al. (2013) evaluated the conception rate at 30 days of pregnancy in recipient embryos produced in vitro undergoing Embryo Transfer in Fixed Time (FTET), supplemented with sunflower seed for 22 days from the removal of the device. The conception rate in Sunflower group was greater than in Control [55.66% (59/106) vs. 36.94% (41/111) respectively, p <0.01]. The increase in conception rate of females supplemented may arise from changes in the endometrium, embryo, fetus and / or corpus luteum. Many studies are being conducted by the group in an attempt to understand the mechanisms by which sunflower seed increases the conception rate. In the study by Souza et al. (2013) it was found in embryo recipients that higher concentrations of total cholesterol were observed in Group Sunflower in D7 compared to control (3.06 + 0.11 vs. 2.77 + 0.11 respectively, p <0.05 ) and D19 (2.60 + 0.07 vs. 2.31 + 0.07 mg / dl, respectively, p <0.01) and higher HDL concentrations were observed in the control group compared to the sunflower D7 (1, 66 + .08 vs. 1.39 + 0.05 mg / dL, respectively, p <0.01) and D19 (1.62 + 0.04 vs. 1.35 + 0.04 mg / ml, respectively, p <0 , 01), these precursors of progesterone (P4). However, in this study, the plasma concentration of P4 in D7 did not differ (p <0.05) between the Sunflower Group (4.92 ± 0.24 ng / mL) and control (4.72 + 0.23 ng / mL) . The hypothesis is that supplementation with sunflower seed did not alter the percentage of large luteal cells (CLG) and small luteal cells (CLP) in the corpus luteum (CL) of females supplemented with sunflower seed. Thus the objective is to perform a quantitative analysis of the luteal cells in Nelore supplemented or not for 7 and 15 days after D0 (D0 = day of expected estrus, which is two days after the removal of the device). Nelore cows (n = 36) will be submitted to a synchronization protocol. On the removal of intra-vaginal devices (D0) females will be divided into two groups to receive 1.7 kg / animal / day of one of the following treatments: 40% of soybean meal with 44% crude protein (CP) and 60% Sunflower Seed (Sunflower Seed Group, n = 12) or 53% of soybean meal with 44% CP and 47% corn (control group, n = 12). The two supplements to the animals will be equally balanced in energy and protein, both with 72% TDN and 24% CP, but not increased or increased with sunflower seed. The supplement will be provided daily from D0 until slaughter. The treated females in each group will be subdivided according to the day of slaughter into four groups: control group D7 (n = 6), Group Sunflower Seed D7 (n = 6) and control group D15 (n = 6) and Group Seed Sunflower D15 (n = 6). The corpus luteum subjected to morphometric analysis by a system of computerized image analysis connected to a light microscope and a video camera. The luteal tissue will be assessed for the following parameters: percentage of CLG against whole cells of CL, CLP percentage in relation to the total cells of the CL; CLG percentage in relation to total steroidogenic cells, percentage of CLP in relation to total steroidogenic cells, the total area occupied by CLG in relation to the total area of the CL, the total area occupied by the CLP in relation to the total area of the CL; percentage of endothelial cells in the total cell CL.
News published in Agência FAPESP Newsletter about the scholarship: