Navegando por Autor "Rodrigues, Naiara Nantes"

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    Growth performance, reproductive parameters and fertility measures in young Nellore bulls with divergent feed efficiency
    (2022) Rossi, Guilherme Fazan; Bastos, Natália Marins; Vrisman, Dayane Priscila; Rodrigues, Naiara Nantes; Vantini, Roberta; Garcia, Joaquim Mansano; Dias, Erika Aline Ribeiro; Simili, Flávia Fernanda; Guimarães, André Lasmar; Canesin, Roberta Carrilho; Mercadante, Maria Eugênia Zerlotti; Freitas-Dell’Aqua, Camila de Paula; Athayde, Flávia Regina Florencio de; Monteiro, Fabio Morato; Mingoti, Gisele Zoccal
    Abstract The growth, sexual maturity and fertility-related parameters related of young Nellore bulls with divergent residual feed intake (RFI) raised on pasture were evaluated. After classification of 48 young males as low and high RFI (more and less efficient, respectively), the animals were evaluated for growth and reproductive parameters at 28-day intervals from 14.3 to 24.6 months of age. The semen was cryopreserved in the last sampling and fresh and post-thaw semen samples were evaluated. Low RFI bulls exhibited higher initial and final body weight (P < 0.05), but feed intake, body condition score and growth measures evaluated by carcass ultrasound were unaffected by RFI (P > 0.05). The scrotal circumference, sperm concentration, defects, and quality of fresh semen, and ultrasonographic testicular characteristics were unaffected by RFI (P > 0.05). However, velocity parameters such as average path and curvilinear velocities determined by computer-assisted sperm analysis of thawed semen submitted to the rapid thermoresistance test were improved (P < 0.05) in low RFI bulls, but this improvement in quality did not enhance in vitro sperm fertilizing ability. Our results demonstrated significant differences in metabolism and growth performance between bulls of divergent RFI. In addition, there was slight improvement in the semen quality of bulls with low RFI bulls, but this did not enhance in vitro fertilizing ability. Selection of beef bulls for RFI can be performed, which will result in economic benefits by improving the growth performance of the animals without affecting reproductive parameters.
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    Relationship of residual feed intake with semen parameters and testicular ultrasound of Nellore bulls
    (2023) Borges, Marcelo Sant’Ana; Silva, Marina de Oliveira; Fernandes, Luana Gomes; Rodrigues, Naiara Nantes; Rossi, Guilherme Fazan; Freitas-Dell’Aqua, Camila de Paula; Bonilha, Sarah Figueiredo Martins; Mercadante, Maria Eugênia Zerlotti; Monteiro, Fabio Morato
    ABSTRACT The objective of this study was to evaluate characteristics of the testicular parenchyma and vascular parameters of the pampiniform plexus obtained by ultrasound, semen quality parameters, and sperm freezability in Nellore bulls classified based on residual feed intake (RFI). Twenty-seven bulls (21.82±0.88 months of age) evaluated for feed efficiency were sampled for the study, including 15 with low RFI (−0.592±0.09 kg dry matter/day) and 12 with high RFI (0.792±0.10 kg dry matter/day). In ultrasound and Doppler assessment, the most efficient animals (low RFI) showed higher pulsatility and resistive indexes, as well as a tendency towards greater heterogeneity of the testicular parenchyma (0.625±0.032 vs. 0.508±0.032, 1.012±0.072 vs. 0.802±0.072, and 12.9±0.96 vs. 10.2±0.96, respectively, for low vs. high RFI). However, these animals tended to have lower peak diastolic velocity (5.19±0.50 for low RFI vs. 6.54±0.50 for high RFI). Analysis of fresh semen showed a lower percentage of minor defects in low RFI animals (2.67±1.19%) compared with high RFI animals (8.10±1.19%), without differences in the other parameters in fresh or thawed semen and after thermoresistance testing. Evaluation of flow cytometry parameters showed a higher quality of mitochondrial respiration in semen samples of low RFI animals (22.04±2.50%) compared with high RFI animals (12.29±2.71%). Therefore, although RFI exerts an effect on the Doppler parameters of the pampiniform plexus, it is not sufficient to affect the quality of fresh or thawed semen.