Abstract
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 compounds rich in linoleic acid, among these the 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]. 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 present study, the hypothesis is that supplementation with sunflower seed promotes further development of the endometrial glands determining an increase in the endometrial glands. It aims to perform a quantitative and morphological endometrial glands in Nelore supplemented with sunflower seed for 7, 15 and 23 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 protocol of estrus and ovulation synchronization by using an intravaginal device containing progesterone 1g associated with an injection of 2mg of estradiol benzoate intramuscularly (IM). Eight days after device placement (D-2) is carried out the removal thereof and the administration of 0.075 mg of D-cloprostenol and 0.6 mg of estradiol cypionate and 300UI of equine chorionic gonadotropin (eCG), both IM. After 48 hours of 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 = 18) or 53% of soybean meal with 44% CP and 47% corn (Control Group, n = 18). 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 in six groups: Control Group D7 (n = 6), Group Sunflower Seed D7 (n = 6) and Control Group D15 (n = 6); Seed Group Sunflower D15 (n = 6); D23 Control Group (n = 6) and Group D23 Sunflower Seed (n = 6). After the killing of females will be sectioned a piece of 1cm thick taking the total diameter of the middle third of the uterine horn contralateral to the corpus luteum will be packed in fixative solution buffered formaldehyde (PAF) at pH 7.0 for 24 hours. The fragments are subjected to six successive washes with intervals of 12 hours in a PBS solution at pH 7.5. The fragments are included in paraffin, then sectioned with a microtome slice thickness from 6 to 8 mm stained with hematoxylin and eosin. The endometrial glands are subjected to morphometric analysis by a system of computerized image analysis connected to a light microscope and a video camera. The number of glandular ducts, area and perimeter of the same will be estimated automatically by the Windows Select Measurements by measuring 6 randomly selected fields. The data will be analyzed by ANOVA. This study will be of great importance for understanding the mechanisms by which sunflower seed increases conception rates.
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