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Effects of ressynchronization of estradiol on day 14 after Timed-AI on morphofunctional characteristics of corpus lute and uterus in Nelore females

Grant number: 17/18613-0
Support type:Scholarships in Brazil - Master
Effective date (Start): October 01, 2017
Effective date (End): September 30, 2019
Field of knowledge:Agronomical Sciences - Veterinary Medicine - Animal Reproduction
Principal Investigator:Guilherme Pugliesi
Grantee:Igor Garcia Motta
Home Institution: Faculdade de Medicina Veterinária e Zootecnia (FMVZ). Universidade de São Paulo (USP). São Paulo , SP, Brazil
Associated research grant:15/10606-9 - Innovations in the early pregnancy diagnosis in cattle, AP.JP

Abstract

Detection of non-pregnant cows by Doppler ultrasonography on Days 20-22 (detection of luteolysis) post-first AI can reduce the interval between inseminations in cattle. However, information regarding use of 17beta-estradiol (E2) and estradiol benzoate (EB) to resynchronize the ovulation in pregnant animals is limited, and the results are inconclusive. The main objective with this study is to evalaute the effects of E2 associated with P4 and EB treatments on Day 14 post-TAI on induction of a new follicle wave emergence, luteolysis induction and pregnancy maintenance in Nelore heifers. For this, morphological characteristics observed by B and Color Dopller modes, and the circulanting P4 concentrations were be measured to detect the changes in the folicular dynamics and function of corpus luteum and uterus em beef heifers from 3 experimental groups (n=10/group): control (only intravaginal P4 device), E2+P4 and BE+P4. Also, the morphofunctional changes on uterus indetified by ultrassonography will be used to imporve the early pregnancy diagnosis technique. Is expected that low doses of E2 and BE associated to P4 on Day 14 post-TAI are enough to induce new follicle emergence, without negative effects on luteal function and pregnancy maitanence. In Exp., 30 Nelore heifers will be submitted to a TAI protocol, and ultrasonography evaluations on B and Dopller modes will be performed daily from Days 14 to 22 post-TAI. In addition, imune cells will be isolated from the peripherical blood collected on Days 14 and 18 to identify the pregnancy status before (Day14) and after (Day18) hormonal treatments. Ultrassongraphy exams will be also done on Day 25 to identify the occurence of ovulation and embryo vesicle, respectively, in non-pregnant and pregnant animals. In Exp. 2, we aim to use the best hormonal treatment observed in Exp. 1 and compare the pregnancy rate after ressynchronization and second TAI in relation to the control group (n= 200/group).

Scientific publications
(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)
MOTTA, I. G.; ROCHA, C. C.; BISINOTTO, D. Z.; MELO, C. D.; ATAIDE JUNIOR, G. A.; SILVA, A. G.; GONZAGA, V. H. G.; SANTOS, J. A.; FREITAS, B. G.; LEMES, K. M.; MADUREIRA, E. H.; PUGLIESI, G. Increased pregnancy rate in beef heifers resynchronized with estradiol at 14 days after TAI. Theriogenology, v. 147, p. 62-70, APR 15 2020. Web of Science Citations: 1.
PUGLIESI, GUILHERME; DE MELO, GABRIELA DALMASO; ATAIDE, JR., GILMAR ARANTES; GONTIJO PELLEGRINO, CARLOS AUGUSTO; SILVA, JULIO BARBOZA; ROCHA, CECILIA CONSTANTINO; MOTTA, IGOR GARCIA; MORAES VASCONCELOS, JOSE LUIZ; BINELLI, MARIO. Use of Doppler ultrasonography in embryo transfer programs: feasibility and field results. ANIMAL REPRODUCTION, v. 15, n. 3, p. 239-246, JUL-SEP 2018. Web of Science Citations: 6.

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