Embryo death between 15 and 19 days of pregnancy is caused by the increase in the release of endometrial prostaglandin F2α (PGF2α) involved in the luteolysis process in cattle. Compounds rich in linoleic acid, such as sunflower seeds, provide lipid changes in the endometrium, and may be involved in the ability of PGF2α biosynthesis. Previous studies observed that the conception rate increased in Nelore cows supplemented with sunflower seed for 22 days from the timed AI (66.7% v. 46.3%; Peres et al. 2008, Acta Sci. Vet. 36, 639) and in crossbred heifers submitted to timed embryo transfer (55.66% v. 36.94%; Membrive et al. 2013 Acta Sci. Vet. 36, 603). We aimed to test the hypothesis that supplementation with sunflower seed promotes endometrial changes in lipid composition. Thus, we compared the composition of fatty acids in endometrial tissue in cows supplemented or not with sunflower seed. Nelore (n = 30) cows received an intravaginal device containing progesterone (1 g; DIB, Syntex Biochemistry & Pharmaceutical Industries SA, Buenos Aires, Argentina) associated with an im injection of oestradiol benzoate (2 mg; Benzoate HC, Hertape Calier Animal Health SA, Juatuba, MG, Brazil). The devices were removed after 8 days, when cows were treated im with cloprostenol sodium (2 mg; Sincrocio®, Ourofino Animal Health Ltd., Cravinhos, SP, Brazil), oestradiol cypionate (0.5 mg; ECP®, Zoetis Ltda., São Paulo, Brazil) and eCG (300 IU; Folligon®, Intervet Veterinary Ltda., Cotia, Brazil). Two days after removal of the device, females were assigned into 6 groups to receive 1.7 kg/animal/day of 40% soybean meal, 44% crude protein (CP) + 60% sunflower seed for 6 (n = 4), 14 (n = 5) and 22 days (n = 6), or 53% soybean meal, 44% CP + 47% corn for 6 (n = 4), 14 (n = 5) and 22 days (n = 6). Both diets were formulated with 72% total digestible nutrients and 24% CP. Females were slaughtered 24 h after the end of supplementation and endometrial tissue was isolated and stored at –196°C. The fatty acids in endometrial tissue were assessed by gas chromatography. Data were analysed by SAS Proc GLIMMIX (SAS Institute Inc., Cary, NC, USA). The fatty acid profile (54 compounds) was analysed and 43 fatty acids were present in the endometrial tissue. The lacking fatty acids in endometrial tissue were C4:0, C11:0, C12:1, C: 13:0, C13:0 iso, C13:0 anteiso, C14:0 iso, C15:1, C18:1 trans-16, C18:2 cis-12, trans-10, and C21:0. The fatty acids that showed a higher percentage compared with the Control group were C18:1 trans-10-trans-11-trans-12 and C10:1. The fatty acids that showed low percentage compared with the Control group were C15:0 iso, C20:5, C20:3n-3, C23:0, C24:0, and C22:5. In conclusion, supplementation with sunflower seed promotes changes in the endometrial lipid profile that may reduce the pregnancy loss in beef cows.
Research supported by FAPESP, FUNDUNESP, and Santa Encarnação Farm.
