Banca de QUALIFICAÇÃO: GUSTAVO FERNANDES GRILLO

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : GUSTAVO FERNANDES GRILLO
DATE: 16/08/2021
TIME: 14:00
LOCAL: Encontro remoto via plataforma Zoom
TITLE:

Evaluation of the Procedure of Embryo Transfer in Cattle as a Means of Transmission of the Parasite Neospora caninum. 

KEY WORDS:

Embryo transfer, gestacional losses, pregnancy rates, bovines.

PAGES: 34
BIG AREA: Ciências Agrárias
AREA: Medicina Veterinária
SUBÁREA: Reprodução Animal
SPECIALTY: Inseminação Artificial Animal
SUMMARY:

The use of biotechniques as a reproductive management tool has evolved significantly in recent decades, increasing reproductive efficiency in dairy cattle. Among the biotechniques, Fixed-Time Artificial Insemination (FTAI), Embryo Transfer (ET) and in vitro Fertilization (IVF) the most evolved and currently used in reproductive programs for dairy herds. Despite their capacity, it is necessary to understand the factors related to their success for their application, thus the development of studies that assess the superovulatory response, pregnancy rates and pregnancy losses can contribute to increased effectiveness. The strict sanitary control of the herds becomes essential so that the respective programs can provide the expected gains in reproductive efficiency. In this way, two experiments were developed. The first experiment aimed to detect, through the PCR technique, the DNA of Neospora caninum in embryos from seropositive cows in superovulation protocols for embryo transfer. Among recipients of embryos from seropositive and seronegative donors, no differences were found in the pregnancy rate (60 and 57.1%, P=0.57), gestational loss (50% and 43.8%, P=0.79) and number of embryos produced after superovulation (40 and 51, P=0.64). There was also no change in the serological status of the recipients, regardless of the status of the donor, as well as the protozoan DNA in embryos and PBS samples from the uterine lavage performed for embryo flushing were not identified. Thus, it can be demonstrated that the TE technique is safe and can be used in neosporosis control programs, noting that despite the similarity in the number of embryos, there was a significant difference in the number of freezeable (25% and 74%, P <0.0001) and transferable (27.5% and 78.4%, P<0.0001) structures. The second study evaluated the effect of increasing circulating progesterone (P4) by inducing accessory corpus luteum (CL) formation in recipients of cloned (SCNT) and in vitro produced (IVF) embryos. As expected, treatment with hCG caused ovulation and increased circulating P4, although hCG tended to increase pregnancies by ET (P/ET) for SCNT embryo recipients on days 28 (P = 0.07) and 42 (P = 0.09). Pregnancy rates were similar for IVF and SCNT embryos on days 28 and 33, however, P/ET was higher for IVF than SCNT on day 42 and later, due to higher (P = 0.05) pregnancy losses in SCNT (44.4%) than IVF embryos (15.0%) from days 33-42. Thus, increasing circulating P4 may improve fertility in recipients of SCNT embryos, as evidenced by the tendency of treatment with hCG to increase P/ET of SCNT embryos. Although additional research is needed, it can be concluded that ET is a viable technique for the genetic improvement of the herd, which can also be used to control diseases such as bovine neosporosis.

BANKING MEMBERS:
Presidente - 1548043 - MARCO ROBERTO BOURG DE MELLO
Interna - 1201559 - VERA LUCIA TEIXEIRA DE JESUS
Externo à Instituição - EDWARDS FRAZAO-TEIXEIRA - FIOCRUZ
Externo à Instituição - JOAQUIM ESQUERDO FERREIRA - CESVA
Externo à Instituição - ÂNGELO JOSÉ BURLA DIAS - UENF