Use of color-Doppler ultrasonography for selection of recipients in timed-embryo transfer programs in beef cattle

• Published in: Theriogenology 2019-09, Vol.135, p.73-79
• Main Authors: Pugliesi, Guilherme, Dalmaso de Melo, Gabriela, Silva, Júlio Barboza, Carvalhêdo, Alexandre Sardinha, Lopes, Everton, de Siqueira Filho, Emivaldo, Silva, Luciano Andrade, Binelli, Mario
• Format: Article
• Language: English
• Subjects: Animals; Blood perfusion; Cattle; Cattle - physiology; Corpus luteum; Embryo Transfer - veterinary; Female; Follicle; Ovary - anatomy & histology; Ovary - physiology; Pregnancy; Pregnancy Rate; Pregnancy success; Progesterone - blood; Ultrasonography, Doppler, Color - veterinary
• ISSN: 0093-691X; 1879-3231
• DOI: 10.1016/j.theriogenology.2019.06.006

We aimed to study the association between CL characteristics assessed by color-Doppler ultrasonography (Doppler-US) at the time of embryo transfer (ET) and pregnancy rate (P/ET) in beef recipients. Estrous cycles of crossbred beef recipients were synchronized for timed-ET. On the day of ET (Day 7), CL area, proportion of luteal blood perfusion (BP), and the relationship between the largest dominant follicle (DF) and CL (ipsilateral or contralateral) were determined. Animals (n = 444) received an in vitro produced embryo from Nelore donors, placed in the uterine horn ipsilateral to the CL. Recipients were split retrospectively in three subgroups according to CL area [small (4 cm2)] and three subgroups according to luteal signals of BP [low (≤40%), medium (45–50%) or high (≥55%)]. Pregnancy was detected on Days 30–45 by transrectal ultrasonography and P/ET was analyzed considering the effects of cow's category (suckling or non-suckling), CL area, luteal BP and side of DF. P/ET increased along with BP category [low, 45.9%B, (62/135); medium, 54.1%AB (93/172); and high, 58.4%A (80/137)]. When luteal BP was evaluated as a continuous variable, a significant (P