Banca de DEFESA: GEORGE MOREIRA DA SILVA

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
DISCENTE : GEORGE MOREIRA DA SILVA
DATA : 26/05/2021
HORA: 14:00
LOCAL: Embrapa - online
TÍTULO:

Spermatic degree of hyperactivation and estrus on pregnancy in timed AI beef cows

PALAVRAS-CHAVES:

Heat detection, sperm kinetics, time of ovulation.

PÁGINAS: 62
GRANDE ÁREA: Outra
ÁREA: Multidisciplinar
RESUMO:

The objective of this study was to determine the effect of the degree of sperm hyperactivity and estrus on the pregnancy of inseminated cows at fixed time. The hypotheses tested in the present study were: 1) cows that manifest estrus within 48 hours after the removal of the progesterone implant ovulates earlier; 2) sperm kinetics affect the fertility of cows that have been in heat or without heat until the time of the IATF. For the elaboration of the master's dissertation, two experiments were carried out, which are described in the form of a scientific article. The objective of Experiment 1 was to determine the time of ovulation of animals that manifested heat or without heat within 48 hours after removal of the CIDR. In this study, 24 primiparous Nellore cows were subjected to an IATF protocol based on estradiol and progesterone (2 mg BE + CIDR on D0 / 150 μg d-Cloprostenol on D8 + 300 IU eCG + 1 mg ECP - CIDR on D8 / IATF 48h). The animals received an estrus detector device (Estrotect) and were categorized into two groups according to the manifestation of estrus (Cio and SCio) within 48 hours after removal of the CIDR. Ultrasound evaluations were performed to detect the moment of ovulation and pregnancy diagnosis 35 days after IATF. Subsequently, 12 cows that were diagnosed as not pregnant were resynchronized, totaling 36 AIs, 19 animals from the Cio group and 17 SCio animals. The results of experiment 1 demonstrated that the animals in the Cio group ovulated earlier (P <0.02) compared to SCio cows (73.3 ± 13.1 vs. 95.5 ± 37.5h). In Experiment 2, 475 multiparous Nellore cows were subjected to the same protocol described in Experiment 1. All animals were painted with a marker stick in the lumbosacral region to identify estrus. In AI, 2 semen matches from 2 different bulls were used, previously analyzed by the computational method (Analysis of computer-assisted semen - CASA), and the following variables were taken into account to determine sperm kinetics, as previously described (Pfeifer et al. 2019): curvilinear speed (VCL), amplitude of lateral displacement of the head (ALH) and linearity (LIN). Matches considered hyperactive (H +; LIN <50.6%, ALH> 7 μm and VCL> 149 μm / s), and non-hyperactivated (H-; LIN> 55.5%, ALH <6.3 μm and VCL < 142.5 μm / s). At the time of AI, the cows were divided into four groups according to the manifestation of heat (Cio and SCio) and the degree of seminal hyperactivity (H- and H +): CioH +, CioH-, SCioH + and SCioH-. The diagnosis of pregnancy was performed 30 days after IATF using ultrasound. There was no effect (P = 0.10) of sperm kinetics on the P / AI rate. However, the CioH + (60.3%, 88/146) and CioH- (66.9%, 99/148) groups had a higher P / AI rate (P <0.02) compared to the ScioH + groups (49, 1%, 55/112) and ScioH- (47.8%, 33/69). The results of this study showed that cows that express estrus within 48 hours after P4 removal ovulate earlier and are more likely to conceive at IATF. However, sperm kinetics did not affect the fertility of beef cows that expressed estrus or not at the time of IATF.

MEMBROS DA BANCA:
Presidente - 958.305.370-87 - LUIZ FRANCISCO MACHADO PFEIFER - EMBRAPA
Interno - 162.237.228-00 - ANA KARINA DIAS SALMAN - EMBRAPA
Externo à Instituição - ERIKLIS NOGUEIRA - EMBRAPA
Externo à Instituição - ELIZANGELA MIRIAM MOREIRA - UFAM