Banca de QUALIFICAÇÃO: SAMUEL RODRIGUES BONAMICHI DO COUTO

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : SAMUEL RODRIGUES BONAMICHI DO COUTO
DATE: 20/12/2021
TIME: 13:00
LOCAL: Encontro remoto via plataforma Google Meet
TITLE:

Strategies to increase the reproductive efficiency of Nellore cows with reactive temperament submitted to TAI.

KEY WORDS:

cattle, stress, blood flow, progesterone, fertility.

PAGES: 64
BIG AREA: Ciências Agrárias
AREA: Medicina Veterinária
SUBÁREA: Reprodução Animal
SPECIALTY: Inseminação Artificial Animal
SUMMARY:

The present study was divided into two chapters, the first one having as main objective to correlate different progesterone (P4) supplementation strategies in Nellore females with temperament and cortisol concentration. Additionally, the effect of these strategies and animal temperament on conception rate was evaluated. The second chapter aimed to evaluate the efficiency of different strategies to increase the concentration of circulating P4 in Nelore females on the functionality of the corpus luteum (CL), conception rate and on pregnancy loss. For the two experiments, 212 cows were subjected to ovulation synchronization and fixed-time insemination (TAI). After TAI, the animals were divided into three groups: P4LA (n=70) 150mg of long-acting injectable progesterone, 7 days after TAI; GnRH (n=68), 10μg buserelin acetate, 7 days after TAI; Control group (n=74) without hormone application. B-mode ultrasound evaluations (preovulatory follicle - POF) were performed on the day of the AI and color Doppler (CL) assessments were performed on the day of insemination, 7 and 16 days later. Blood samples were collected on the day of the TAI as well as on the 7th and 16th days after, for measurement of cortisol and P4, respectively. In the first chapter, at the time of insemination, the animals were scored according to their behavior, through this assessment they were classified as excitable (EXC) or adequate (ADQ) temperament animals. Animals classified as excitable had higher cortisol concentrations and lower volumes of POF and CL seven days after TAI. There was no significant difference between the variables intensity and number of pixels in the CL, in addition to the concentrations of P4, seven days after insemination. Among the EXC animals, the GnRH and P4LA groups had higher concentrations of P4. There was a trend towards lower P4 concentration in EXC animals when compared to ADQ in the control group (p=0.06). The animals in the control group classified as EXC had lower vascular perfusion compared to ADQ (p=0.04). Among ADQ animals, the GnRH and P4LA groups had lower vascular perfusion compared to the control (p=0.04). Among the EXC animals, a higher conception rate was observed for the GnRH and P4LA groups compared to the control (p=0.07). In the control group, the conception rate of ADQ animals was higher compared to EXC animals (p=0.01). In experiment 2, no significant difference was observed between treatments in the variables volume, intensity and number of pixels in the CL, as well as in relation to P4 concentration, 7 days after ovulation. The vascular perfusion of the CL 16 days after ovulation was lower in the P4LA and GnRH groups (P<0.01). Plasma concentrations of P4, 16 days after ovulation, were higher in the P4LA and GnRH groups compared to the control group (P=0.04). There was no significant difference in the conception rate (P=0.29) and in the pregnancy loss (P=0.14) as a function of the treatments. It is concluded that the use of GnRH or P4 seven days after ovulation affects the vascularization of the CL increases plasma concentrations of P4 sixteen days after ovulation and improves conception rates in excitable animals, being a viable alternative to minimize the negative impact of stress and improve reproductive rates.

BANKING MEMBERS:
Presidente - 1548043 - MARCO ROBERTO BOURG DE MELLO
Interna - 1201559 - VERA LUCIA TEIXEIRA DE JESUS
Externo ao Programa - 2142739 - RODRIGO VASCONCELOS DE OLIVEIRA
Externo ao Programa - 2316004 - RONDINELI PAVEZZI BARBERO
Externo à Instituição - JOAQUIM ESQUERDO FERREIRA - CESVA