Banca de DEFESA: SAMUEL RODRIGUES BONAMICHI DO COUTO

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : SAMUEL RODRIGUES BONAMICHI DO COUTO
DATE: 27/05/2022
TIME: 08:00
LOCAL: Encontro remoto via plataforma Google Meet
TITLE:

Strategies to increase reproductive efficiency in bovine females with different temperaments submitted to TAI.

KEY WORDS:

Cattle, stress, blood flow, progesterone, fertility.

PAGES: 65
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 of which aimed 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 Nelores females on the functionality
of the corpus luteum (CL), conception rate and on pregnancy loss. For the two experiments,
939 cows were submitted to ovulation synchronization and inseminated at a fixed time (FTAI).
After the FTAI, the animals were divided into three groups: P4LA (n=70) 150mg of long-acting
injectable progestagen, 7 days after the FTAI; GnRH (n=68), 10μg buserelin acetate, 7 days
after FTAI; Control Group (n=74) without hormone application. B-mode ultrasound
assessments (preovulatory follicle - PFO) were performed on the day of 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 FTAI as well as on the 7th and 16th days after, for
cortisol and P4 measurements, respectively. In the first chapter, at the time of insemination, the
animals were scored according to the behavior presented, through this evaluation they were
classified as excitable (EXC) or suitable (ADQ) animals. Animals classified as excitable had
higher concentrations of cortisol and lower volumes of OPF and CL, seven days after FTAI.
No significant difference was observed between the variables intensity and number of CL pixels
in addition to P4 concentrations, seven days after insemination. Among EXC animals, the
GnRH and P4LA groups showed higher concentrations of P4. There was a trend towards lower
P4 concentration in EXC animals when compared with ADQ in the control group (p=0.06).
Control group animals classified as EXC had lower vascular perfusion compared to ADQ
(p=0.04). Among ADQ animals, the GnRH and P4LA groups showed 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=0.01). In the control
group, the conception rate of ADQ animals was higher compared to EXC animals (p=0.05). In
experiment 2, no significant difference was observed between treatments in the variables
volume, intensity and number of CL pixels, as well as in relation to P4 concentration, 7 days
after ovulation. CL vascular perfusion 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 a significant difference
in the conception rate (P=0.003) and a trend in pregnancy loss (P=0.07) 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 in order to
minimize the negative impact of stress and improve reproductive indices.

BANKING MEMBERS:
Presidente - 1548043 - MARCO ROBERTO BOURG DE MELLO
Interno - 2202309 - JULIO CESAR FERRAZ JACOB
Externo ao Programa - 2316004 - RONDINELI PAVEZZI BARBERO
Externo à Instituição - MARCELO SIMÃO DA ROSA - IFMG
Externo à Instituição - ÂNGELO JOSÉ BURLA DIAS - UENF