Chickens are ideal model organism to improve understanding of several research areas as phylogenetic, embryology, biomedicine, livestock, and have recently been suggested as a promising model for epigenetic studies. In the livestock area, chickens are source of protein to humans and had been selected to achieve a high production standards based on genetic breeding by the traditional selection. We are now in the genomics and epigenomics era and it is time be concern about the use of new tools to improve selection not only thinking about production, but also in the health and welfare of animals. The use of molecular approaches, have been a fundamental tool to understand biological models and improve selection strategies based on genomic information in breeding programs. Molecular approaches have also contributed to understanding of the evolutionary history of these models and the genetics and epigenetics mechanisms involved in evolution process and genetic diversification of chickens. In this context, many technologies have emerged to produce high-throughput data using Next-generation sequencing (NGS) approaches. NGS provided a large amount of information for diverse purposes such as to detect single nucleotide polymorphisms (SNPs), and methylated DNA profiles in chickens. In addition, NGS has allowed the development of pre-designed SNP arrays for genome-wide association studies (GWAS) with specific phenotypes of interest. Moreover, although NGS has enough power to detect informative polymorphisms, its high cost makes it impractical to be used in GWAS and Methylated DNA immunoprecipitation sequencing (MeDIPseq) studies. The demand for an economical, efficient, simple-step and reliable genome-wide method of SNPs discovery, validation and characterization, was the reason for the development of this study. We applied reduced representation sequence by restriction enzyme (RE) cleavage of target chicken genome to be applied in GWAS. Thereafter, to combine the reduced representation of the genome with MeDIPseq method, we developed a novel approach to perform differential methylation studies using reduced libraries. These works allowed us to identify SNPs associated with performance traits and differential methylation windows related to different stress conditions in chickens. / A galinha é um organismo modelo ideal para melhorar o entendimento de diversas áreas da pesquisa como: filogenética, embriologia, biomedicina, pecuária, e tem sido recentemente sugerida como um modelo promissor para estudos em epigenética. Na pecuária, as galinhas são fonte de proteína para os seres humanos e tem sido alvo de seleção para alcançar um alto padrão de produção com base no melhoramento genético tradicional. Mas agora, estamos na era genômica e epigenômica e as atenções devem ser voltadas para o uso de novas ferramentas para melhorar a seleção não só pensando em produção, mas também na saúde e bem-estar dos animais. O uso de abordagens moleculares, tem sido uma ferramenta fundamental para compreender modelos biológicos e melhorar as estratégias de seleção baseadas na informação genômica em programas de melhoramento. Abordagens moleculares, também tem contribuído para a compreensão da história evolutiva desses modelos e os mecanismos genéticos e epigenéticos envolvidos no processo de evolução e diversificação genética das galinhas. Neste contexto, tecnologias evoluíram para produção de dados de sequenciamento de alto rendimento por sequenciamento de próxima geração (NGS). NGS forneceu uma grande quantidade de informação a ser utilizado para diversos fins, como para detectar polimorfismos de nucleotídeo único (SNPs) e perfis de metilação diferencial do DNA em galinhas. NGS tem permitido também o desenvolvimento de painéis de SNP para testes de associações genômica ampla (GWAS) com fenótipos específicos de interesse. Embora NGS tem poder suficiente para detectar polimorfismos informativos, o seu elevado custo o torna impraticável para ser utilizado em GWAS ou estudos de metilação diferencial por sequenciamento de DNA metilado por imunoprecipitação (MeDIPseq). A procura de um método de genotipagem eficiente, simples, econômico e confiável para descoberta, caracterização e validação de SNPs, foi a razão para o desenvolvimento deste estudo. Utilizamos sequenciamento do genoma reduzido por enzima de restrição (RE) que cliva o genoma alvo para identificação de SNPs nestas bibliotecas reduzidas e aplicação deste método em GWAS. Em seguida, para combinar a representação reduzida do genoma com o método MeDIPS, desenvolvemos uma nova abordagem para a realização de estudos de metilação diferencial utilizando as bibliotecas reduzidas. Estes trabalhos permitiram a identificação de SNPs associados com características de desempenho e janelas de metilação diferencial relacionados a diferentes condições de manejo em galinhas.

O gene DMRT3 tem sido descrito como o principal gene a atuar na determinação da marcha em diversas raças equinas. O alelo A do SNP 23:g.22999655C>A do DMRT3 foi apontado como responsável por essa característica. Na raça brasileira Mangalarga Marchador, a qual apresenta dois padrões de marcha com características bem definidas, os genótipos AA e CA vem sendo associados à marcha picada e o genótipo CC à marcha batida. O objetivo geral do presente prospectar regiões genômicas associadas às marchas batida e picada em equinos Mangalarga Marchador. Foram utilizados 1.230 dados fenotípicos sobre o tipo de andamento (marcha batida N = 1.006; marcha picada N = 227) e, considerando a totalidade da genealogia conhecida para cada animal, 3172 animais no pedigree. Primeiramente foram testadas estratégias de modelagem para esta característica a fim de determinar os efeitos a serem considerados no modelo, bem como a melhor forma de inclusão (efeito fixo ou aleatório). Posteriormente, foi estudada a relação entre as frequências alélicas e genotípicas do gene DMRT3 com os padrões de parentesco e endogamia de acordo com cada tipo de marcha. Um estudo de associação genômica ampla em passo único (considerando informações de animais genotipados e não-genotipados simultaneamente) foi conduzido para verificar regiões genômicas, polimorfismos de nucleotídeo único e genes relacionados com a determinação do tipo de marcha em cavalos Mangalarga Marchador. Vinte e dois polimorfismos de nucleotídeo único localizados nos cromossomos 4(N = 5), 6 (2), 16 (1), 23 (11), 26 (1) e 29 (2), foram responsáveis por 42,43% da variância genética aditiva. Foram associados ao tipo de marcha 69 genes, mas cerca de 39 não estavam anotados em equinos. Foi conduzido um blast a fim de recuperar a função mais provável destes genes. Foram encontradas oito vias metabólicas associadas ao tipo de marcha. Os principais genes envolvidos estavam relacionados à percepção de estímulos externos, metabolismo energético-oxidativo, sistema imune e aprendizado e ritmo da locomoção. Não foi possível identificar a(s) variante(s) causal(ais) do tipo de marcha, contudo este estudo foi o primeiro e verificar que a possível determinação genética do tipo de marcha em cavalos Mangalarga Marchador passa por diferenças em níveis metabólicos que garantem a adaptação dos animais ao tipo de andamento. / The DMRT3 gene has been described as the main gene to act in gait determination in several equine breeds. The allele A of the SNP 23:g.22999655C>A of DMRT3 gene was identified as responsible for this trait. In the Brazilian Mangalarga Marchador breed, which presents two gait patterns with characteristics well defined, the AA and CA genotypes have been associated with marcha picada gait and CC genotype with marcha batida gait. The general aim of this study was to prospect genomic regions associated with marcha batida and marcha picada gaits in Mangalarga Marchador equines. 1,230 phenotypic data were used on the type of gait (marcha batida N = 1.006; marcha picada N = 227) and, considering the totality of known genealogy for each animal, 3,172 animals in the pedigree. Firstly, modelling strategies were tested for this trait in order to determine the effects to be considered in the model, as well as the best form of inclusion (fixed or random effect). Based on the best modelling strategy to be used, the relationship between the allelic and genotypic frequencies of the DMRT3 gene with kinship and inbreeding patterns was studied according to each type of gait. A single-step wide genomic association study (considering information from both genotyped and non-genotyped animals simultaneously) was conducted to verify genomic regions, single nucleotide polymorphisms and genes related to determination of gait type in Mangalarga Marchador horses. Twenty two single nucleotide polymorphisms located on chromosomes 4 (N = 5), 6 (2), 16 (1), 23 (11), 26 (1) and 29 (2) were responsible for 42.43% of the additive genetic variance. 69 genes were associated with gait type, but about 39 were not annotated in horses. A blast was conducted in order to recover the most likely function of these genes. Eight metabolic pathways were found associated with gait type and the main genes involved were related to the perception of external stimuli, energy-oxidative metabolism, immune system and learning and rhythm of locomotion. It was not possible to identify the causal variant(s) of the type of gait; however, this study was the first and to verify that the possible genetic determination of gait type in Mangalarga Marchador horses goes through differences in the metabolic levels that guarantee the adaptation of the animals to the type of gait.

Thesis (M.Sc.) (Agriculture) --University of Limpopo, 2007 / The objectives of this study were to evaluate the effect of pre-weaning selection on estimates of genetic parameters for post-weaning average daily gain in Phases C (ADG-C) and D (ADG-D) and to estimate genetic relationships between average daily gain in the two phases. Performance records of the South African Angus cattle breed was used in the analysis. (Co)variance components and genetic parameters for weaning (WWT), AGD-C and ADG-D were estimated by REML procedures fitting three different models (Models 1, 2 and 3) that differed in how they integrated sequential selection in the analysis of post-weaning traits. Model 1 was a univariate model of WWT, ADG-C and ADG-D. Model 2 was a two trait model of WWT and either ADG-C or ADG-D. Model 3 was a three trait model of WWT, ADG-C and ADG-D. Estimates of heritability for ADG-C were 0.39±0.08, 0.42±0.06 and 0.44±0.01 from Model 1, 2 and 3 respectively. Corresponding estimates of heritability for ADG-D were 0.18±0.021, 0.19±0.021 and 0.21±0.02 respectively. An estimate of genetic correlation between ADG-C and ADG-D was 0.58± and it suggested that the two traits may not necessarily be under the same genetic control. Rank correlations for all bulls based on ADG-C estimated breeding values (EBV’s) were 0.92, 0.83 and 0.94 for Model 1 vs. Model 2, Model 1 vs. Model 3 and Model 2 vs. Model 3 respectively. Corresponding ADG-D EBV’s rank correlations were 0.88, 0.84 and 0.93. Rank correlations for top and bottom 1%, 5% and 10% were lower than those for all bulls in both ADG-C and ADG-D. Low rank correlations showed that the difference in magnitude of genetic parameters from different models was enough to alter bull rankings based on EBV’s of ADG-C and ADG-D. Hence it was concluded that inclusion of pre-weaning information in genetic analysis for post-weaning average daily gain is necessary to account for selection at weaning. / the THRIP (Technology and Human Resource for Industry Project) and NRF (National Research Foundation).

Thesis (MSc. (Animal breeding and genetics )) --University of Limpopo, 2006 / The objective of this study was to estimate genetic parameters for weekly body weight of feed intake of individually fed beef bulls at centralized testing stations in South Africa using random regression models (RRM). The model for cumulative feed intake included the fixed linear regression on third order orthogonal Legendre polynomials of the actual days on test (7, 14, 21, 28, 35, 42, 49, 56, 63, 70, 77 and 84 day) for starting age group and contemporary group effects. Random regressions on third order orthogonal Legendre polynomials were included for the additive genetic effect of the animal and the additional random effect of weaning-herd-year (WHY) and on fourth order for the additional random permanent environmental effect of the animal. The model for body weights included the fixed linear regression on fourth order orthogonal Legendre polynomials of the actual days on test for starting age group and contemporary group effects. Random regressions on fourth order orthogonal Legendre polynomials were included for additive genetic effects and additional uncorrelated random effects of the WHY and the permanent environment. The residual effects for both traits were assumed to be independently distributed with heterogeneous variance for each measurement period. Variance ratios for additive genetic, permanent environment and WHY for cumulative feed intake at different days on test ranged from 0.07 to 0.10, 0.53 to 0.77 and 0.14 to 0.37, respectively. Variance ratios for additive genetic, permanent environment and WHY for weekly body weights at different test days ranged from 0.26 to 0.29, 0.37 to 0.43 and 0.26 to 0.34, respectively. Estimates of genetic correlation among the same trait (body weight or feed intake) measured at different test days were generally high (>0.80) for any give test pair. The WHY had a significant contribution in variation of performance of bulls on test, despite the 28-day adjustment period. RRM provided the opportunity to study changes in genetic variability within the studied traits over time. Random Regression Models could be used in the National Genetic Evaluation of beef bulls at central performance testing stations in South Africa.

This thesis is concerned with a theoretical simulation model for pig breeding, as part of the ongoing search for the “perfect” genotype. The starting point is an additive model to investigate how accurately the classical, infinitesimal model predicts genetic gain for traits controlled by few loci and few alleles. This initial investigation demonstrates that the infinitesimal model is robust, providing that at least 15 loci are controlling a trait and there is symmetry in the allele distributions. A Genotype-Pig (GE-Pig) model is then developed to apply the additive effects of alleles on sub-phenotypic traits like maximum protein deposition, minimum lipid to protein content in the whole body, ad libitum digestible energy intake, energy for maintenance requirement and water content in the whole body. These parameters are then used in a nutrient partitioning simulation model to growth a pig and calculate traditional breeding traits such as average daily gain, feed conversion ratio, and backfat thickness for any combination of alleles. Three algorithms, Genetic Algorithm, Tabu Search, and Simulated Annealing, are used to investigate the GE-Pig model and find optimal combination of alleles for different dietary and selection objective situations. The two diets investigated were either of a low or high quality, and the three selection objectives used were, maximising average daily gain, minimizing feed conversion ratio, and minimizing back fat. A graphical method is developed for easy comparison of the genotypes. Of the algorithms, the Genetic Algorithm performed the best, followed by Tabu Search and finally Simulated Annealing. It is demonstrated that, in general, there is a different, single, optimum for any given selection objective and diet. However under the back fat selection objective, both diets produce the same optimal genotype. Also there are many similarities between the optima for the average daily gain and feed conversion ratio selection objectives. When the theoretical minimum number of generations of selection to the optima is considered, the feed conversion ratio selection objective is the quickest for a breeding program to achieve the optimal solutions, followed by back fat, then average daily gain. It is demonstrated that diet also has an effect on the theoretical number of generations. A Multiple selection objective, using relative economic values applied to the individual selection objectives, is also investigated. For both diets, the majority of the multiple selection objective solutions are in the vicinity of the feed conversion ratio optima, indicating that feed conversion ratio is the most prominent factor. It is also demonstrated that the optimal solution is most affected by the objective parameter weights under low diet conditions.

Diss. (sammanfattning). Uppsala : Sveriges lantbruksuniversitet, 2005. / Härtill 4 uppsatser.

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniv., 2003. / Härtill 5 uppsatser.

CAPES / A análise genética é uma ferramenta que pode auxiliar na busca de melhores índices zootécnicos na ovinocultura leiteria. Há muitos anos as curvas de lactação e a estimação dos componentes de variância dos parâmetros calculados a partir delas, vêm sendo utilizadas nas estratégias de manejo em fazendas leiteiras, pois é possível alterar o formato da curva de lactação por meio da seleção. No Brasil, há uma grande lacuna sobre conhecimento técnico relacionado aos ovinos leiteiros no país. A estimação dos parâmetros da curva de lactação e posterior estimação dos componentes de variância permitem um melhor entendimento dos componentes genético e ambiental que afetam a produção, antecipando as informações necessárias para a tomada de decisão sobre o direcionamento do manejo genético dos rebanhos. O objetivo do trabalho foi estimar os componentes de variância e os parâmetros genéticos dos componentes da curva de Wood em um rebanho de ovinos da raça Lacaune. Foram utilizadas 3558 informações de ovinos da raça Lacaune, e estimados os componentes de variância e os parâmetros genéticos dos parâmetros para a produção inicial (a), acréscimo até o pico (b), decréscimo após o pico (c), dia do pico (d), produção no pico (p), persistência (ln(s)) e produção total (y) da curva de Wood via estimação Bayesiana por meio do método de amostragem de Gibbs. A média estimada para os parâmetros a, b, c, d, p, ln(s) e y foram 0,362; 0,135; 0,032; 3,911; 1,703; 4,049; 76,249, respectivamente. As herdabilidades médias estimadas foram 0,41 (a), 0,47 (b), 0,50 (c), 0,11 (d), 0,30 (p), 0,36 (ln(s)) e 0,002 (y). As correlações fenotípicas e genéticas entre o parâmetro a e as demais variaram de -0,13 a 0,39 e -0,06 a 0,24, respectivamente. No parâmetro b variaram de - 0,002 a 0,17 e 0,04 a 0,15, parâmetro c de -0,01 a 0,11 e 0,04 a 0,10, parâmetro d de - 0,13 a 0,39 e -0,02 a 0,11, parâmetro p de -0,15 a 0,39 e -0,12 a 0,24, parâmetro ln(s) de -0,15 a 0,39 e -0,12 a 0,11, e para o parâmetro y variaram de -0,002 a 0,33 e 0,04 a 0,08. As repetibilidades identificadas foram 0,81 (a), 0,94 (b), 0,98 (c), 0,22 (d), 0,60 (p), 0,71 (ln(s)) e 0,003 (y). Conclui-se que as estimativas médias de herdabilidade e correlações identificadas evidenciaram um forte efeito ambiental afetando a expressão da característica produção de leite e baixas correlações genéticas entre os parâmetros da curva e a produção, indicando que a seleção pela produção de leite trará pouco ganho genético. Por outro lado, a seleção considerando todos os parâmetros da curva pode ser mais conveniente. Além disso, fica evidenciada a necessidade da padronização do manejo do rebanho. Devem ser elaborados estudos mais detalhados que permitam entender a relação dos parâmetros. O banco de dados pode ser trabalhado em outros períodos de lactação para um melhor conhecimento das estimativas dos componentes de variância. Seria de grande valia estudos sobre componentes principais e análise de trilha para posterior utilização no método de índice de seleção, para corroborar com a seleção que considera todos os parâmetros da curva. / Genetic analysis is a tool that can help in the search for better zootechnical indexes in dairy sheep breeding. For many years the lactation curves and the estimation of variance components of the parameters calculated from them have been used in management strategies in dairy farms since it is possible to change the shape of the lactation curve through selection. In Brazil, there is a large gap regarding technical knowledge related to dairy sheep in the country. The estimation of lactation curve parameters and subsequent estimation of the components of variance allow a better understanding of the genetic and environmental components that affect production, anticipating the information necessary for decision making on the direction of the genetic management of the herds. The aim of this work was to estimate the components of variance and the genetic parameters of the components of the Wood curve in a herd of Lacaune sheep. We used 3558 information from Lacaune sheep, and estimated the variance components and genetic parameters of the parameters for initial production (a), increase to peak (b), decrease after peak (c), peak day (d), peak production (p), persistence (ln (s)), and total production (y) of the Wood curve via Bayesian estimation using the Gibbs sampling method. The estimated mean for parameters a, b, c, d, p, ln (s) and y were 0.362, 0.135, 0.032, 3.911, 1.703, 4.049, 76.249, respectively. The estimated mean heritabilities were 0.41 (a), 0.47 (b), 0.50 (c), 0.11 (d), 0.30 (p), 0.36 (ln (s)) and 0.002 (y). The phenotypic and genetic correlations between parameter a and the others ranged from -0.13 to 0.39 and -0.06 to 0.24, respectively. In parameter b ranged from -0.002 to 0.17 and 0.04 to 0.15, parameter c of -0.01 to 0.11 and 0.04 to 0.10, parameter d of -0.13 to 0.39 and - 0.02 to 0.11, parameter p of -0.15 to 0.39 and -0.12 to 0.24, parameter ln (s) of -0.15 to 0.39 and -0.12 to 0.11, and for the parameter y ranged from -0.002 to 0.33 and 0.04 to 0.08. The repeatability identified were 0.81 (a), 0.94 (b), 0.98 (c), 0.22 (d), 0.60 (p), 0.71 (ln (s)) and 0.003 (y). It was concluded that the average estimates of heritability and correlations showed a strong environmental effect affecting the expression of the characteristic milk production and low genetic correlations between the parameters of the curve and the production, indicating that the selection by milk production will bring little genetic gain. On the other hand, the selection considering all parameters of the curve may be more convenient. In addition, the need for standardization of herd management is evidenced. More detailed studies should be developed to understand the relationship of the parameters. The database can be worked on in other lactation periods for a better understanding of the variance component estimates. It would be of great value studies on main components and track analysis for later use in the selection index method, to corroborate with the selection that considers all parameters of the curve.

Made available in DSpace on 2014-06-11T19:32:16Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-07-22Bitstream added on 2014-06-13T19:02:45Z : No. of bitstreams: 1 cardonacadavid_h_dr_jabo.pdf: 617128 bytes, checksum: 52904037b788868ea51cbb64af8ea362 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Na bovinocultura de leite, a alta contagem de células somáticas (CCS) é considerada indicativo da condição de mastite. A mastite ainda continua sendo a doença de maior prevalência em gado leiteiro, causando altos custos. Em rebanhos bufalinos no estado de São Paulo, a presença de mastite subclínica e clínica representam 1,5% e 18,77%, respectivamente, das búfalas em lactação. Isto pode levar à diminuição na produção e na qualidade do leite. Considerando-se que não é possível erradicar essa doença devido a sua origem ser multifatorial (fatores genéticos e ambientais), todos os esforços devem ser concentrados no sentido de manter sua prevalência a mais baixa possível. Assim sendo, o objetivo de nosso estudo foi estimar os parâmetros genéticos para a CCS e produção de leite e identificar polimorfismos nos genes B-defensina 1 e 4. Na estimação dos parâmetros genéticos para a CCS e produção de leite (P305) foram utilizadas 4.907 lactações de 1986 búfalas contidas no arquivo zootécnico mantido pelo Departamento de Zootecnia da Faculdade de Ciências Agrárias da UNESP de Jaboticabal, as quais foram analisadas por meio de inferência bayesiana em análises bicaracterística, empregou-se um modelo animal. Para a caracterização dos genes b-defensina 1 e 4 foram utilizadas amostras de DNA genômico de 132 búfalas de diferentes regiões do estado de São Paulo, empregou-se a técnica de PCR/RFLP (Reação em Cadeia da Polimerase/ Polimorfismo do Comprimento dos xiii Fragmentos de Restrição). As estimativas de herdabilidade da CCSt (h2=0.27) e da P305 (h2=0.25) foram... / In dairy cows, high-somatic cell count (CCS) in milk is considered indicative of the mastitis condition of the mammary gland. Mastitis, inflammation of the mammary glands of dairy animals both clinical and subclinical, results in significant economic losses because of lower milk yields and its degraded quality, early culling and loss of genetic potential, higher veterinary expenses and increased labour costs for a farmer. In buffaloes from São Paulo State, the presence of clinical and subclinical mastitis represent losses between 1,5% and 18,77% of dairy milk buffaloes. This fact causes a diminution of production in the milk quality, interfering in mozzarella production, which is to making utilizing this specie milk. We known that is not possible disappear this illness because their multifactorial source (genetics and environmental factors), all effort will be concentrated in the direction of to keep the prevalence as low that possible. Because the importance of the mastitis in animal dairy, in the last year increase the number of study of defensin genes, which are a group of multifunctional peptides, due to the role played by defensins in defending animals from bacterial, viral, or fungal infections, the genes encoding them seem to be potential markers of the genetically determined susceptibility (or resistance) of the mammary gland. Defensins are present not only in the mammary gland, but also in milk, as well as in leukocyte granules and in macrophages which constitute a part of milk cell population. The β-defensins are cationic peptides. It is a group of antimicrobiana peptides with antibiotic and cytotoxic activity against bacterium xv viruses and fungi. Interest in the β-defensins has grown substantially in recent years, because of their antimicrobiana properties and because... (Complete abstract click electronic access below)

A seleção genômica é a mais moderna tecnologia no que tange a utilização de marcadores genéticos para a seleção e melhoramento genético de animais domésticos. Em síntese a metodologia consiste em uma seleção assistida por marcadores em uma escala ampla do Genoma e foi proposta por Meuwissen et al. (2001). O desequilíbrio de ligação (DL) entre os marcadores e loci de características quantitativas (QTL) e a composição da população referência são pontos chave para a confiabilidade da seleção genômica. À medida que os indivíduos se distanciam geneticamente, o DL entre marcadores e QTL diminui, o que dificulta a aplicação da seleção genômica em populações de animais multirraciais e explica o fato de até hoje a maior parte das pesquisas se concentrarem na estimação de valores genômicos apenas para animais de raças puras. A aplicação dessa metodologia em populações multirraciais de bovinos constitui uma possibilidade real de grandes avanços no melhoramento genético do rebanho brasileiro de bovinos de corte. / Genomic Selection is the newest technology into the use of genetic markers at the animal breeding. In sinthesys the metodology consists in a marker assisted selection in a genome wide scale, it was pourpused by Mewissent et al. (2001). The linkage disequilibrium between the marker and quantitative trait loci (QTL) and the composition of the reference population are key points to the reablility of the genomic selection. Once the individuals get genetically distants, the DL between markers and QTLs decays, what turns hard the aplication of genomic selection in multirracial populations of animals and explains the fact of untill today the major part of researchs are dedicated to the estimation of genomic breeding values only to purebreed animals. The aplication of this methodology in multibreed cattle populations consists in a real possibility to reach greats advances in genetic improvement of the brazilian beef cattle heard.