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Search Results: 1 - 10 of 163614 matches for " Toral Fábio Luiz Buranelo "
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Número e intervalo de pesagens para estima??o de parametros de curvas de crescimento em bovinos
Toral, Fábio Luiz Buranelo;
Revista Brasileira de Zootecnia , 2008, DOI: 10.1590/S1516-35982008001200007
Abstract: this study aimed to evaluate the minimum number and interval of weightings to estimate the asymptotic weight (a) and maturing rate (k) parameters of the growth curve of cattle. parameters a and k of the richards non-linear model and two data sets of weights of cattle from 1 to 3,601 days were simulated. the first data set consisted of 13 to 121 weights obtained every 30 days and the second one consisted of weightings at intervals of 30 to 150 days. the decrease in number of weightings used to estimate a and k reduced the correlations between estimated and simulated parameters and increased the bias and the residuals mean square. the increase in the interval of weightings did not affect the estimates of a, but had a damaging effect on the estimates of k. weightings every 30 days and over four years, every 60 days and over five years or every 90 days and over six years, at least, are sufficient to estimate the parameters a and k of the richards non-linear model for cattle.
Alternatives for analysis of performance data and ranking of Charolais x Nellore crossbred bulls in performance tests
Toral, Fábio Luiz Buranelo;Alencar, Maurício Mello de;
Revista Brasileira de Zootecnia , 2010, DOI: 10.1590/S1516-35982010000700013
Abstract: it was evaluated alternatives for analysis of performance records and ranking of charolais x zebu crossbred bulls. data of weight at six ages and average daily weight gain in eight periods of 883 21/32 charolais + 11/32 nellore bulls in performance tests were used. the direct additive genetic values were predicted in single trait analysis using animal models with classificatory fixed effects of contemporary groups and age of dam at calving and age of animal at weighing as linear covariable, depending on the trait. as random effects, it was considered the direct additive genetic effect, the permanent maternal environmental and residual effects for all traits. phenotypic values adjusted for fixed effects included in the model of each trait were also obtained. the spearman correlation between predicted direct additive genetic values and adjusted phenotypic values ranged from 0.43 to 0.95, depending on the trait and year of birth of the animals. the accuracies of genetic values increased according to the number of animals with utilized data and they were always higher to those estimated for the adjusted phenotypic values. the magnitude of change in ranking the bulls depends on the considered trait. the estimates of correlations of predicted genetic values with the real genetic values of the analyzed traits of growth are higher than those among the adjusted phenotypic values and the real genetic values.
Estruturas de variancia residual para estima??o de fun??es de covariancia para o peso de bovinos da ra?a Canchim
Toral, Fábio Luiz Buranelo;Alencar, Maurício Mello de;Freitas, Alfredo Ribeiro de;
Revista Brasileira de Zootecnia , 2009, DOI: 10.1590/S1516-35982009001100012
Abstract: this study was carried out to evaluate the use of different residual variance structures to estimate covariance functions for weight of canchim beef cattle. the covariance functions were estimated by the restricted maximum likelihood method, in an animal model with fixed effect of contemporary group (year and month of birth and sex), age of dam at calving as covariable (linear and quadratic effects) and mean growth trajectory while the random effects considered were the direct additive genetic and maternal effects, permanent individual environment and maternal and residual effects. different structures were used for residual variance: ordinary polynomials of different orders (linear to fifth) and step functions with 1, 5, 10, 15 and 20 classes. homogeneous residual variance was not adequate. the four-ordered variance function and the step function with 20 classes presented the best fit and the class division was more efficient than residual functions. the estimated heritabilities were between 0.16 and 0.25, and the greatest ones were obtained close to 360 days and at the end of the study period. the estimated heritabilities were similar for models with homogeneous residual variance, four-ordered residual function and step model with 20 classes of heterogeneous variances. the best description of residual variance, for weights at different ages of canchim beef cattle, was by step function with 20 classes of heterogeneous variances. however, as existing classes with the same variances, they can be grouped to reduce the number of parameters to be estimated.
Alternativas de análises em dados de medidas repetidas de bovinos de corte
Freitas, Alfredo Ribeiro de;Presotti, Cátia Valéria;Toral, Fábio Luiz Buranelo;
Revista Brasileira de Zootecnia , 2005, DOI: 10.1590/S1516-35982005000700010
Abstract: data consisting of individual records of male and female animals of purebred bos indicus beef cattle (nellore, guzerá, gir and indubrasil) weighted every three months from birth to 24 months of age available from national archive of brazilian zebu breeders association (abcz) were used to evaluate two alternatives (co)variance analyses for body weight. in the first analysis the box-cox family transformation yil = (yl-l)/l (l 1 0) or yi = log yi, for l=0 was effective in reducing the asymmetry of the coefficients and variance heterogeneity for all weights and breeds. in the second analysis a usual standard mixed model for repeated measures was used to evaluate covariance structures which accounted for the within-individual variances using the goodness of fit criteria provided by proc mixed: c2 distribution for the null hypothesis, akaike's information criterion and schwarz's bayesian criterion. the best covariance structure for all breeds was the unstructured followed by the factor-analytic for nellore, gir and indubrasil breeds and the heterogeneous composed symmetry for the guzera breed.
Abordagens freqüentista e bayesiana para avalia??o genética de bovinos da ra?a Canchim para características de crescimento
Toral, Fábio Luiz Buranelo;Alencar, Maurício Mello de;Freitas, Alfredo Ribeiro de;
Revista Brasileira de Zootecnia , 2007, DOI: 10.1590/S1516-35982007000100006
Abstract: this study aimed to: a) to compare the covariance components obtained by restricted maximum likelihood (reml) and by bayesian inference (bi); b) to run genetic evaluations for weights of canchim cattle measured at weaning (w240) and at eighteen months of age (w550), adjusted or not to 240 and 550 days of age, respectively, using the mixed model methodology with covariance components obtained by reml or by bi; and c) to compare selection decisions from genetic evaluations using observed or adjusted weights and by reml or bi. covariance components, heritabilities and genetic correlation for w240 and w550 were estimated and the predicted breeding values were used to select 10% and 50% of the best bulls and cows, respectively. the covariance components obtained by reml were smaller than the a posteriori means obtained by bi. selected animals from both procedures were not the same, probably because the covariance components and genetic parameters were different. the inclusion of age of animal at weighing as a covariate in the statistical model fitted by bi did not change the selected bulls and cows.
Arranjos para efeitos fixos e estruturas de (co)variancias residuais para análises de medidas repetidas do peso de bovinos da ra?a Canchim
Toral, Fábio Luiz Buranelo;Alencar, Maurício Mello de;Freitas, Alfredo Ribeiro de;
Revista Brasileira de Zootecnia , 2006, DOI: 10.1590/S1516-35982006000700010
Abstract: the aim of this work was to evaluate arrays of fixed effects and residual covariance structures that best fit the herd and the animal variability to weights at birth, weaning, twelve and eighteen months of 3,690 canchim animals. different arrays of fixed effects (contemporary groups and, or the main effects of year, month or season of birth and sex) and different residual covariance structures (considering or not change of variance and of correlation between weights at different ages) were studied. the results indicated that the most adequate array of fixed effects to fit herd variability was the contemporary group of year, month and sex. the best residual covariance structures were the first-order factor analytic and the unstructured, which consider increase of residual variance as age increases and different correlation between pair of weights at different ages.
Valor nutritivo e desempenho de coelhos alimentados com ra es contendo milheto (Pennisetum glaucum (L.) R.Br)
Furlan Antonio Claudio,Scapinello Claudio,Toral Fábio Luiz Buranelo,Faria Haroldo Garcia de
Revista Brasileira de Zootecnia , 2003,
Abstract: Três experimentos foram conduzidos com o objetivo de determinar o valor nutritivo e verificar o desempenho de coelhos em crescimento alimentados com ra es contendo diferentes níveis de milheto. No ensaio de digestibilidade (experimento 1) foram determinados os valores nutritivos dos milhetos dos cultivares Comum, BN2 e Iapar IA 98301. Foram utilizados 40 coelhos machos da ra a Nova Zelandia Branco, com idade média de 45 dias, distribuídos em um delineamento inteiramente casualizado, com 10 repeti es. Em cada tratamento, os milhetos avaliados substituíram 30% de uma ra o referência. Os valores de energia digestível dos milhetos Comum, BN2 e Iapar IA 98301 foram, respectivamente, 3410, 3493 e 3505 kcal/kg de matéria natural. Nos ensaios de desempenho (experimentos 2 e 3) foram avaliadas ra es contendo níveis crescentes de milheto Comum ou Iapar IA 98301 (0, 25, 50, 75 e 100%) em substitui o ao milho. Em cada ensaio foram utilizados 60 coelhos da ra a Nova Zelandia Branco, sendo 30 machos e 30 fêmeas, com 40 dias de idade inicial, distribuídos em um delineamento inteiramente casualizado, com 12 repeti es, sendo a unidade experimental constituída por um animal. N o foram observadas diferen as no desempenho dos coelhos quando o milho foi substituído pelo milheto Comum. Foram observados efeitos quadráticos dos níveis de substitui o do milho por milheto Iapar IA 98301. Menor ganho de peso, pior convers o alimentar e menor peso de carca a foram obtidos, respectivamente, com a substitui o de 64,09; 58,03 e 63,58% de milheto IA 98301 às ra es, entretanto, com 100% de substitui o os resultados foram satisfatórios. Pode-se concluir que os cultivares de milheto estudados apresentaram bom valor nutritivo e que, o milheto Comum ou Iapar IA 98301 podem substituir o milho nas ra es de coelhos em crescimento.
Digestibilidade de Duas Fontes de Amido e Atividade Enzimática em Coelhos de 35 e 45 Dias de Idade
Toral Fábio Luiz Buranelo,Furlan Antonio Claudio,Scapinello Cláudio,Peralta Rosane Marina
Revista Brasileira de Zootecnia , 2002,
Intera??o genótipo x ambiente em características de crescimento de bovinos da ra?a Nelore no Mato Grosso do Sul
Toral, Fábio Luiz Buranelo;Silva, Luiz Otávio Campos da;Martins, Elias Nunes;Gondo, Andrea;Simonelli, Sandra Maria;
Revista Brasileira de Zootecnia , 2004, DOI: 10.1590/S1516-35982004000600011
Abstract: the effect of genotype x environment interaction on body weight at birth (bw), weaning (w205), 12 (w365) and 18 (w550) months of age of nellore cattle raised in the regions of alto taquari, campo grande and pantanal, ms, brazil, was studied. the data were analyzed for each region separately and for all regions together. variance and covariance components and genetic parameters were estimated by the restricted maximum likelihood method, using an animal model that included the random additive direct effect, and the fixed effects of sex and contemporary group (herd, year, season and region of birth), and sires were ranked based on their breeding values (bv). the results showed that the additive direct and residual variances were different among regions. the heritability estimates ranged from 0.16 to 0.66 (bw), 0.36 to 0.59 (w205), 0.35 to 0.49 (w365) and 0.30 to 0.45 (w550), depending on the region. pearson's correlation coefficients between bvs of sires, obtained for each pair of regions, showed means equal to 0.11 (bw), 0.38 (w205), 0.38 (w365) and 0.39 (w550). when the correlations were for the bvs obtained for each region with the bvs obtained for all regions together, the estimates were higher showing means equal to 0.80 (bw), 0.88 (w205), 0.88 (w365) and 0.87 (w550). despite the high values of these last ones, the results show evidence of genotype x environment interaction, and that regional genetic evaluations, when available, can be more useful than a state evaluation.
Estimativas de parametros genéticos para características de crescimento e produtividade em vacas da ra?a Canchim, utilizando-se inferência bayesiana
Mello, Silvio de Paula;Alencar, Maurício Mello de;Toral, Fábio Luiz Buranelo;Gianloren?o, Viviane Karina;
Revista Brasileira de Zootecnia , 2006, DOI: 10.1590/S1516-35982006000100011
Abstract: the objective of this study was to estimate genetic parameters for body weights at weaning (pd), 12 months old (p12) and adult age (pad), culling age (tpr, days in herd), number (nd10) and kilograms (qd10) of calves weaned up to ten years of age, total number (ndt) and total kilograms (qdt) of calves weaned during herd life, and kilograms of calves weaned per year in herd (qtpr) of canchim (5/8 charolais + 3/8 zebu) females from one herd. data consisted of 3,249, 3,111, 1,138, 1,340, 1,362, 1,362, 1,340, 1,340 and 1,340 records of pd, p12, pad, tpr, nd10, qd10, ndt, qdt and qtpr, respectively. variance and covariance components were estimated by bivariate analyses between pd, p12 and pad and other production traits using bayesian inference. the models included the additive direct, permanent environmental and residual random effects and the fixed effects year and month of birth or calving, calving age and age of the animal, depending on the trait. qd10, qdt and qtpr of each female were obtained by adjusting the weaning weights of calves for year and month of birth, sex and age of cow. average of heritability estimates were 0.38 (pd), 0.40 (p12), 0.54 (pad), 0.22 (tpr), 0.22 (nd10), 0.24 (qd10), 0.23 (ndt), 0.23 (qdt) and 0.32 (qtpr), indicating genetic variability to obtain response by selection. genetic correlations between tpr (-0.02, 0.26 and -0.12), nd10 (0.04, 0.10 and -0.29), qd10 (0.37, 0.39 and -0.13), ndt (-0.03, 0.14 and -0.25), qdt (0.20, 0.33 and -0.16), qtpr (0.21, 0.28 and -0.19) and body weights (pd, p12 and pad) suggest that selection of females based on weaning and 12-month body weights will not affect productivity. however, it may be decreased by increasing female adult body weight.
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