oalib

Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99

Submit

Any time

2018 ( 5 )

2016 ( 2 )

2015 ( 37 )

2014 ( 44 )

Custom range...

Search Results: 1 - 10 of 945 matches for " Irineu Umberto;Razook "
All listed articles are free for downloading (OA Articles)
Page 1 /945
Display every page Item
Dias ao Parto de Fêmeas Nelore de um Experimento de Sele o para Crescimento: II - Modelo de Regress o Aleatória
Mercadante Maria Eugênia Zerlotti,Packer Irineu Umberto,Razook Alexander George,Melo Claudio Manoel Rodrigues de
Revista Brasileira de Zootecnia , 2002,
Abstract: Os parametros genéticos para dias ao parto foram estimados usando um modelo de regress o aleatória, com polin mios ortogonais da idade na monta (em anos) como covariável. Os registros de dias ao parto (4.118) foram provenientes de 926 vacas de três rebanhos Nelore experimentais, sendo os rebanhos sele o e tradicional selecionados para maior peso ao sobreano, e o rebanho controle selecionado para a média do peso ao sobreano. As variancias genética aditiva e permanente de ambiente foram descritas por uma fun o polinomial de ordem 4, com nove medidas de erro, resultando em variancias fenotípica e genética aditiva altas nas idades mais avan adas, principalmente após a 6a monta. As herdabilidades estimadas aumentaram de 0,08 a 0,28 da 1a à 6a monta. As correla es genéticas foram médias entre o primeiro desempenho e os demais (0,32 a 0,66), altas entre os desempenhos adjacentes (0,98 a 0,99), e um pouco menores entre os n o adjacentes (0,63 a 0,98). A sele o para peso n o alterou o valor genético médio das vacas dos rebanhos selecionados, entretanto, os valores genéticos médios das vacas do rebanho controle mostraram tendência de queda no decorrer dos anos.
Quadrados mínimos e modelo misto no acesso à estimativa da resposta direta à sele??o em rebanhos experimentais de bovinos Nelore
Mercadante, Maria Eugênia Zerlotti;Packer, Irineu Umberto;Razook, Alexander George;Cyrillo, Joslaine Noely dos Santos Gon?alves;
Revista Brasileira de Zootecnia , 2003, DOI: 10.1590/S1516-35982003000500012
Abstract: records of body weight at selection of nelore cattle pertaining to the sert?ozinho's experimental station (sp-brasil) nelore herds were used to study the influence of the incorporation of additional information on the estimation of annual genetic trend by least squares and mixed model methodologies. the genetic changes in all three nelore herds (control-nec and selected-nes and net) or only in the selected ones (nes and net) were estimated, only for the females, by least squares, by mixed model including their performances and the relationship matrix, and by mixed model incorporating all available information (males and females records and the relationship matrix). the incorporation of all information provided a smoother curve of the annual means throughout the years and consequently an annual genetic trend estimate with lower standard error. least squares provided highly variable annual estimates showing a lower capability of partitioning the genetic change from the environmental change. the mixed model analysis utilizing part of the performance records provided very low annual genetic trend estimates showing a confounding of the environmental with the genetic change.
Quadrados mínimos e modelo misto no acesso à estimativa da resposta direta à sele o em rebanhos experimentais de bovinos Nelore
Mercadante Maria Eugênia Zerlotti,Packer Irineu Umberto,Razook Alexander George,Cyrillo Joslaine Noely dos Santos Gon?alves
Revista Brasileira de Zootecnia , 2003,
Abstract: Registros do peso à sele o de bovinos Nelore pertencentes aos rebanhos experimentais da Esta o Experimental de Zootecnia de Sert ozinho, foram usados para estudar o acréscimo de informa es no acesso à estimativa da mudan a genética anual, utilizando métodos de quadrados mínimos e de modelo misto. A mudan a genética nos três rebanhos (controle-NeC, e selecionados-NeS e NeT) ou somente nos selecionados (NeS e NeT) foi estimada, só para fêmeas, por quadrados mínimos, por modelo misto considerando somente o desempenho das fêmeas e incorporando a matriz de parentesco, e por modelo misto incorporando todas as informa es disponíveis (registros de machos e fêmeas e matriz de parentesco). A incorpora o de todas as informa es disponíveis em modelo misto para estimar a mudan a genética ao longo dos anos forneceu uma curva mais suavizada das médias anuais e, consequentemente, uma estimativa da tendência genética anual com menor erro-padr o. O método dos quadrados mínimos forneceu estimativas da mudan a genética ao longo dos anos altamente variáveis, evidenciando a menor capacidade de particionar a mudan a genética da mudan a ambiental. O modelo misto incorporando parte das informa es de desempenho forneceu estimativas da tendência genética anual muito baixas (viesadas), evidenciando o confundimento da mudan a ambiental com o restante da mudan a genética n o estimada pela ausência de informa es.
Dias ao Parto de Fêmeas Nelore de um Experimento de Sele o para Crescimento: I - Modelo de Repetibilidade
Mercadante Maria Eugênia Zerlotti,Packer Irineu Umberto,Razook Alexander George,Cyrillo Joslaine Noely dos Santos Gon?alves
Revista Brasileira de Zootecnia , 2002,
Abstract: Registros de datas de entrada na monta e respectiva data do parto, referentes a 1.247 fêmeas Nelore dos rebanhos experimentais da Esta o Experimental de Zootecnia de Sert ozinho (IZ - SP), selecionadas para altos (sele o e tradicional) e para médios (controle) pesos ao sobreano foram usados para obter a variável dias ao parto, a fim de estudar o efeito da sele o para crescimento sobre o desempenho reprodutivo. Arquivos de novilhas e de vacas e novilhas foram analisados incluindo e n o incluindo as n o paridas. Nenhuma diferen a significativa foi detectada entre os registros provenientes das vacas dos rebanhos selecionados e do controle, apesar das vacas do rebanho sele o apresentarem as maiores médias de dias ao parto na maioria dos arquivos estudados. Concordando com os resultados obtidos para o efeito de rebanho, o peso à sele o foi significativo somente para as vacas e novilhas, considerando as n o paridas, com tendência das mais pesadas à sele o apresentarem menores valores para dias ao parto. Modelos nos quais n o foi considerado o peso à sele o forneceram os mesmos resultados para o efeito de rebanho. As herdabilidades variaram de 0,02 a 0,16, sendo as mais altas obtidas em arquivos nos quais foram incluídos os registros das n o paridas, indicando que a observa o de caracteres de reprodu o somente das fêmeas férteis contribui para mascarar as diferen as genéticas entre os animais, e quando esta variabilidade é re-introduzida, designando-se penalidades às fêmeas que n o pariram, as diferen as genéticas entre os animais aparecem. Existem evidências que a sele o para peso n o comprometeu o desempenho reprodutivo das fêmeas, mesmo sendo criadas em condi es ambientais similares.
Estima??o da composi??o química do corpo vazio de animais Nelore e Caracu a partir das composi??es química e física do corte da 9a-10a-11a costelas
Bonilha, Sarah Figueiredo Martins;Packer, Irineu Umberto;Razook, Alexander George;Figueiredo, Leopoldo Andrade de;Alleoni, Guilherme Fernando;Resende, Flávio Dutra de;
Revista Brasileira de Zootecnia , 2008, DOI: 10.1590/S1516-35982008001200019
Abstract: linear regressions were developed to estimate the chemical empty body composition of cattle from three genetic groups (caracu, cas; selected nellore, nes; and control nellore, nec) using the physical and chemical compositions of the 9th-10th-11th rib section. fifty six intact males (20 cas, 20 nes and 16 nec) were slaughtered at 20-24 months of age. the content of water, protein, ether extract and ashes were determined in rib section and on samples obtained after grinding and homogenization of all body tissues (blood, hide, head + feet, viscera and carcass). the physical components muscle, fat and bones were also determined in the rib section. the best estimates of empty body components were obtained using the same estimator components as in rib section. the amounts of water and ether extract of the rib section accurately allowed to estimate the total water, ether extract and protein in the empty body of animals. the amounts of muscle and fat in the rib section allowed estimating with efficiency the total of water, ether extract and protein in the empty body of animals. to estimate the empty body total ashes three multiple equations were developed (one for each genetic group) with satisfactory coefficients of determination. these equations included as estimators the amounts of muscle and fat in the rib section. the physical and chemical compositions of the rib section can satisfactorily estimate the chemical components of the empty body of animals. equations described in the literature can estimate with precision the amounts of ether extract and water in the body empty of animals of this study.
Efeitos da sele??o para peso pós-desmame sobre características de carca?a e rendimento de cortes cárneos comerciais de bovinos
Bonilha, Sarah Figueiredo Martins;Packer, Irineu Umberto;Figueiredo, Leopoldo Andrade de;Alleoni, Guilherme Fernando;Resende, Flávio Dutra de;Razook, Alexander George;
Revista Brasileira de Zootecnia , 2007, DOI: 10.1590/S1516-35982007000600008
Abstract: data from 44 bulls of the genetic groups selection nellore (nes), control nellore (nec) and caracu (ca) herds born in 1999 were used to evaluate the effects of selection for post weaning weight on carcass traits and meat cuts yields at 378 days of age (p 378). the animals were randomly distributed into two experimental classes: restricted feeding (ar) and ad libitum feeding (al) including 8 animals from the nes and ca groups and 6 animals from the nec group. animals of each class were slaughtered in pairs when the animals al group reached 4 mm of ultrasonic fat thickness on longissimus dorsi muscle, between the 12th and 13th ribs. the interaction between genetic group and feeding class was not significant for most of the traits evaluated. the genetic group effect was significant. animals of the ca and nes groups were heavier at slaughter and ca animals required longer feedlot period to reach the desired fat thickness. higher slaughter weights of these animals changed their carcass, hindquarter, forequarter and spare ribs weights. the selection for p 378 in the nellore group resulted in heavier weights at slaughter, heavier carcasses and primary cuts, but lower meat tenderness, although within reasonable values of shear force (below 5.0 kgf).
Efeito da sele??o para peso pós-desmame sobre a composi??o corporal de bovinos
Bonilha, Sarah Figueiredo Martins;Packer, Irineu Umberto;Figueiredo, Leopoldo Andrade de;Resende, Flávio Dutra de;Alleoni, Guilherme Fernando;Razook, Alexander George;
Revista Brasileira de Zootecnia , 2007, DOI: 10.1590/S1516-35982007000600009
Abstract: data from 56 bulls of the genetic groups selection nellore (nes), control nellore (nec) and caracu (ca) herds born in 1999 were used to evaluate the effects of selection for weight at 378 days of age (p 378) on the chemical composition of empty body weight. the animals were randomly distributed to three experimental classes: initial slaughter (ai), restricted feeding (ar) and ad libitum feeding (al). the ai class included 4 animals of each genetic group and the ar and al classes included 8 animals from the nes and ca groups and 6 animals from the nec group. after the adaptation period was finished, animals of the ai class were slaughtered and those from the other classes (ar and al) started the feeding period which was defined by the time required by the animals of the al class to reach 4 mm of fat thickness. animals of the ar class of all genetic groups were also slaughtered. the selection for post-weaning weight did not promote any change on body composition of the animals. the interaction between genetic group and feeding class was not significant for most of the traits evaluated. the genetic group effect was significant. lower fat and higher protein percentages of empty body were observed in animals of the genetic group ca, probably due to their larger mature body size.
Dias ao Parto de Fêmeas Nelore de um Experimento de Sele??o para Crescimento: I - Modelo de Repetibilidade
Mercadante, Maria Eugênia Zerlotti;Packer, Irineu Umberto;Razook, Alexander George;Cyrillo, Joslaine Noely dos Santos Gon?alves;Figueiredo, Leopoldo Andrade de;
Revista Brasileira de Zootecnia , 2002, DOI: 10.1590/S1516-35982002000700014
Abstract: records of start of breeding season and subsequent calving, from 1,247 nelore females raised at sert?ozinho experimental station (iz ? sp, brazil), selected for high (selection and traditional lines) and for average (control line) yearling weights were used to compute days to calving and to study the effect of selection for yearling weight on reproductive performance. data sets of heifers, and cow and heifers were analyzed with and without non-calvers females. there were no significant differences among the performance of females from selection lines (selection and traditional) and those control line (nec), although days to calving were higher in the selection line for all data sets. according to the results for the selection line effect, the weight at selection was significant only for cows and heifers including non-calvers females, and those with higher weight at selection showed smaller values for days to calving. models without weight at selection showed equivalent results for line. the heritabilities were between 0.02 and 0.16, and the higher estimates were from data sets including non-calvers females, suggesting that the observation of reproductive traits only on fertile females can make-up the genetic differences between the animals and when this variability is re-introduced, assigning penalty for non-calvers females, the genetic differences appear. the results show that the selection for high yearling weight did not compromise female reproductive performance, even being raised under similar environmental conditions.
Dias ao Parto de Fêmeas Nelore de um Experimento de Sele??o para Crescimento: II - Modelo de Regress?o Aleatória
Mercadante, Maria Eugênia Zerlotti;Packer, Irineu Umberto;Razook, Alexander George;Melo, Claudio Manoel Rodrigues de;Cyrillo, Joslaine Noely dos Santos Gon?alves;Figueiredo, Leopoldo Andrade de;
Revista Brasileira de Zootecnia , 2002, DOI: 10.1590/S1516-35982002000700015
Abstract: genetic parameters for days to calving were estimated using a random regression model, with orthogonal polynomials of age at breeding season (in years) as covariable. the records of days to calving (4,118) came from 929 cows from three experimental nelore herds, been the selection and traditional herds selected for higher yearling weight and the control herd selected for the mean of yearling weight. genetic and permanent environmental variances were described by a fourth order polynomial function, with 9 measures of error. the phenotypic and additive genetic variances were high in late records, especially after the 6th breeding season. heritabilities estimates increased from 0.08 to 0.28, from first up to 6th breeding season. genetic correlations were moderate between the first and the later records (0.32 to 0.66), high between adjacent records (0.98 to 0.99), and a little smaller between non adjacent records (0.63 to 0.98). the selection for weight did not alter the average breeding value of cows of selection herds, however the average genetic breeding values of control cows declined through the years.
k-Casein, b-lactoglobulin and growth hormone allele frequencies and genetic distances in Nelore, Gyr, Guzerá, Caracu, Charolais, Canchim and Santa Gertrudis cattle
Kemenes, Paola Augusta;Regitano, Luciana Correia de Almeida;Rosa, Artur Jord?o de Magalh?es;Packer, Irineu Umberto;Razook, Alexander George;Figueiredo, Leopoldo Andrade de;Silva, Nirlei Aparecida;Etchegaray, Maria Ant?nia L.;Coutinho, Luiz Lehmann;
Genetics and Molecular Biology , 1999, DOI: 10.1590/S1415-47571999000400012
Abstract: the genotypes for k-casein (k-cn), b-lactoglobulin (b-lg) and growth hormone (gh) were determined by polymerase chain reaction (pcr) and restriction enzyme digestion in seven breeds of cattle (nelore, gyr, guzerá, caracu, charolais, canchim and santa gertrudis). k-casein had two alleles with the a allele occurring at a higher frequency in bos indicus breeds (0.93, 0.92 and 0.91% for gyr, guzerá and nelore, respectively). the b-lactoglobulin locus had two alleles in all of the breeds. european breeds had a higher frequency of the b-lg a allele than zebu breeds. the gh locus had two alleles (l and v) in bos taurus and was monomorphic (l allele only) in all of the bos indicus breeds evaluated. the highest frequency for the v allele was observed in charolais cattle. the markers used revealed a considerable similarity among breeds, with two main groups being discernible. one group consisted of zebu and santa gertrudis breeds and the other consisted of european and canchim breeds.
Page 1 /945
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.