PPGZoo

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Navegando PPGZoo por Autor "Bignardi, Annaiza Braga"

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    Associação genética entre características de carcaça, crescimento e de reprodução em bovinos braford e brangus
    (Universidade Federal de Mato Grosso, 2021-02-22) Zuim, Deise Mescua; Bignardi, Annaiza Braga; 283.733.228-33; http://lattes.cnpq.br/5149653630729211; Santana Júnior, Mário Luiz; 067.921.646-40; http://lattes.cnpq.br/9205633142085534; Santana Júnior, Mário Luiz; 067.921.646-40; http://lattes.cnpq.br/9205633142085534; Bignardi, Annaiza Braga; 283.733.228-33; http://lattes.cnpq.br/5149653630729211; Pereira, Rodrigo Junqueira; 061.788.896-58; http://lattes.cnpq.br/5707957381561914; Menezes, Gilberto Romeiro de Oliveira; 058.807.516-78; http://lattes.cnpq.br/9971427968154736
    The study was developed with the objective of estimating the genetic association between growth, reproduction and carcass traits obtained by ultrasound in Braford and Brangus cattle. Longissimus muscle area (LMA), and backfat thickness (BFT), postweaning average daily weight gain (ADG), visual scores of conformation (C), precocity (P), muscling (M), size (S), scrotal circumference (SC) at around 420 and 550 days of age, and days to first calving (DFC). The heritability estimates obtained were of moderate magnitude for LMA (0.23 to 0.27) and low for BFT (0.07 to 0.16), supporting the possibility of a favorable response to selection, especially LMA. The most favorable genetic correlations found for visual scores were between P550 and LMA (0.39 to 0.51) and between M550 and LMA (0.32 to 0.41) for Braford, and for Brangus they were between P550 and LMA420 or LMA550 (0.56) and between M550 and LMA (0.17 to 0.51). Estimates of genetic correlation between BFT and P550 were positive and of moderate to high magnitude for Braford (0.33 to 0.58) and Brangus (0.26 to 0.61). The genetic associations between SC and LMA were of low magnitude, however stronger when SC was measured around 550 days for Braford (0.12 to 0.30) and Brangus (0.01 to 0.21). Between SC and BFT, the genetic correlations varied from -0.18 to -0.12 for Braford and from -0.26 to 0.42 for Brangus. There was evidence of a favorable genetic relationship of DFC with LMA (- 0.22 to -0.12) and BFT (-0.26 to -0.22) at different ages in Braford cattle, the same was not observed for Brangus for LMA (0.03 to 0.29) and BFT (0.04 to 0.57). In view of the differences in estimates of genetic correlation between breeds and measurement ages of animals, it is necessary to develop specific selection strategies for each case.
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    Associação genética entre habilidade de permanência no rebanho em partos consecutivos e características de interesse econômico em bovinos nelore
    (Universidade Federal de Mato Grosso, 2021-02-26) Morales, Débora da Silva; Pereira, Rodrigo Junqueira; 061.788.896-58; http://lattes.cnpq.br/5707957381561914; Pereira, Rodrigo Junqueira; 061.788.896-58; http://lattes.cnpq.br/5707957381561914; Santana Júnior, Mário Luiz; 067.921.646-40; http://lattes.cnpq.br/9205633142085534; Bignardi, Annaiza Braga; 283.733.228-33; http://lattes.cnpq.br/5149653630729211
    The trait stayability (STAY) is a way of assessing the female's longevity potential. Measuring the STAY to each cow calving would allow obtaining earlier indicators of longevity. The objective with the present study was to estimate genetic parameters for STAY in consecutive calvings, age at first calving (AFC), days to calving (DC), weaning weight (WW), and yearling weight (YW); the possible genetic association between the STAY in consecutive calvings and AFC, DC, WW and YW; the influence of the animals genetic potential for the traits AFC, DC, WW and YW in the chances of selection for STAY in consecutive calvings in Nellore cattle. The estimation of variance components and subsequent prediction of breeding values was performed through single-trait analyzes. The estimated breeding values (EBV) were then used to analyze the association between STAY and the other traits. For HPR in consecutive calvings, the heritability estimates ranged from 0.02 to 0.06, with an increasing magnitude according to the calving number. For the traits AFC, DC, WW (direct and maternal effects), and YW, the heritability estimates were 0.07, 0.02, 0.17 and 0.08, 0.33, respectively. Genetic correlation estimates between STAY in different calvings ranged from 0.58 to 0.94 and were higher between closer calvings. The correlation estimates between EBV of the intercept coefficient for STAY in consecutive calvings and EBV of AFC, DC, WW (direct and maternal effects), and YW were -0.14, -0.08, 0.05 and 0.005, 0.07, respectively. The influence of genetic potential of reproductive traits on the odds ratio of selection for STAY in consecutive calvings resulted in a decrease in the chance of selection for STAY in all calvings studied when the EBV for AFC or DC were increased. The WW (direct effect) positively influenced the selection for STAY initially and negatively influenced it at the end of the cow's reproductive life. The WW (maternal effect) positively influenced the scenario with greater selection intensity and negatively influenced it in the other scenarios. For the YW, an increase in genetic potential increased the chances of selection for STAY, except for the later calvings of the scenario with greater selection intensity.
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    Interação genótipo ambiente devido ao estresse térmico durante o final da gestação sobre caraterísticas de crescimento de bovinos de corte
    (Universidade Federal de Mato Grosso, 2021-02-25) Alves, Mariana Stucki; Santana Júnior, Mário Luiz; 067.921.646-40; http://lattes.cnpq.br/9205633142085534; Bignardi, Annaiza Braga; 283.733.228-33; http://lattes.cnpq.br/5149653630729211; Bignardi, Annaiza Braga; 283.733.228-33; http://lattes.cnpq.br/5149653630729211; Santana Júnior, Mário Luiz; 067.921.646-40; http://lattes.cnpq.br/9205633142085534; Pereira, Rodrigo Junqueira; 061.788.896-58; http://lattes.cnpq.br/5707957381561914; Zadra, Lenira El Faro; 115.329.428-18; http://lattes.cnpq.br/5118853929961241
    The effect of thermal stress on production traits has been widely studied in cattle. However, the effect of heat stress that females undergo during pregnancy can compromise embryonic nutrition, fetal and placental development, cause a reduction in gestation length, and impair calves' postnatal performance. Thus, this study aimed to estimate genetic parameters associated with thermal stress during late pregnancy for birth weight (BW) and average daily weight gain from birth to weaning (ADG) of Braford and Brangus cattle. The data refer to 73,383 animals of the Braford breed and 45,120 of the Brangus breed, with birth dates between 1974 and 2017. The calves were weighed at birth and at the time of weaning, which occurred around 205 days of age. The average temperature and humidity index (ITU) was calculated over the last days of gestation (60, 70, 80, and 90) for each animal in the analysis. The mean ITU of the final pregnancy period (ITUg) was included in the fixed linear model. The least-squares means (LSM) were calculated for BW and ADG on each ITUg variable to be evaluated. A regression model was applied on the LSM to assess the BW and ADG response pattern in the function of each ITUg. For Braford and Brangus, the fixed model considering the ITUg calculated over 60 days and 70 days before calving, respectively, presented the highest R2 . During the final gestation period, heat stress significantly reduced both the BW and the ADG of the Braford and Brangus cattle. The ADG was reduced by -00021 and -0,0013 kg/ day / ITUg for Braford and Brangus, representing an expressive productive and economic loss for the studied populations. The heritability estimates for the direct effect for BW varied for Braford from 0,35 to 0,62 with an average of 0,45. For Brangus, the estimates were from 0,26 to 0,52 with an average of 0,37. For the maternal effect, they ranged from 0,06 to 0,17 for Braford and 0,07 to 0,35 for Brangus, with a mean of 0,10 and 0,16 respectively. The heritability estimates for direct and maternal effects were 0,07 to 0,27, with a mean of 0,14, and 0,11 to 0,19, with an average of 0,14, respectively for ADG of Braford cattle. These estimates demonstrate substantial heterogeneity of genetic variances along the environmental gradient. The genetic correlations between the same trait in adjacent ITUg values were of high magnitude. However, among extreme and opposite ITUg they were low or even negative, especially for BW. Therefore, the inclusion of this effect in genetic evaluations to identify and select animals genetically more tolerant to thermal stress becomes justified due to its reflexes on the animal's future performance.