Minimizing inter-genotypic competition effects to predict genetic values and selection in forestry genetic tests

The effect of competition is an important source of variation in breeding experiments. This study aimed to compare the selection of plants of open-pollinated families of Eucalyptus with and without the use of competition covariables. Genetic values were determined for each family and tree and for the traits height, diameter at breast height and timber volume in a randomized block design, resulting in the variance components, genetic parameters, selection gains, effective size and selection coincidence, with and without the use of covariables. Intergenotypic competition is an important factor of environmental variation. The use of competition covariables generally reduces the estimates of variance components and influences genetic gains in the studied traits. Intergenotypic competition biases the selection of open-pollinated eucalypt progenies, and can result in an erroneous choice of superior genotypes; the inclusion of covariables in the model reduces this influence.

Genetic parameters for first lactation test-day milk flow in Holstein cows

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Genetic parameters for test-day yield of milk, fat and protein in buffaloes estimated by random regression models

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Estimative of genetic parameters in progeny test of Pinus caribaea Morelet var. hondurensis Barret & Golfari by quantitative traits and microsatellite markers

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

USE OF PROGENY TESTING IN BEEF-CATTLE - PREDICTION OF GENETIC GAIN IN A NELORE CATTLE-BREEDING PROGRAM

Genetic gains predicted for selection, based on both individual performance and progeny testing, were compared to provide information to be used in implementation of progeny testing for a Nelore cattle breeding program. The prediction of genetic gain based on progeny testing was obtained from a formula, derived from methodology of Young and weller (J. Genetics 57: 329-338, 1960) for two-stage selection, which allows prediction of genetic gain per generation when the individuals under test have been pre-selected on the basis of their own performance. The application of this formula also allowed determination of the number of progeny per tested bull needed to maximize genetic gain, when the total number of tested progeny is limited.

Use of progeny testing in beef cattle: Prediction of genetic gain in a Nelore Cattle Breeding Program

Genetic gains predicted for selection, based on both individual performance and progeny testing, were compared to provide information to be used in implementation of progeny testing for a Nelore cattle breeding program. The prediction of genetic gain based on progeny testing was obtained from a formula, derived from methodology of Young and Weiler (J. Genetics 57: 329-338, 1960) for two-stage selection, which allows prediction of genetic gain per generation when the individuals under test have been pre-selected on the basis of their own performance. The application of this formula also allowed determination of the number of progeny per tested bull needed to maximize genetic gain, when the total number of tested progeny is limited.

Estimates of genetic parameters and eigenvector indices for milk production of Holstein cows

The objectives of the present study were to estimate genetic parameters of monthly test-day milk yield (TDMY) of the first lactation of Brazilian Holstein cows using random regression (RR), and to compare the genetic gains for milk production and persistency, derived from RR models, using eigenvector indices and selection indices that did not consider eigenvectors. The data set contained monthly TDMY of 3,543 first lactations of Brazilian Holstein cows calving between 1994 and 2011. The RR model included the fixed effect of the contemporary group (herd-month-year of test days), the covariate calving age (linear and quadratic effects), and a fourth-order regression on Legendre orthogonal polynomials of days in milk (DIM) to model the population-based mean curve. Additive genetic and nongenetic animal effects were fit as RR with 4 classes of residual variance random effect. Eigenvector indices based on the additive genetic RR covariance matrix were used to evaluate the genetic gains of milk yield and persistency compared with the traditional selection index (selection index based on breeding values of milk yield until 305 DIM). The heritability estimates for monthly TDMY ranged from 0.12 ± 0.04 to 0.31 ± 0.04. The estimates of additive genetic and nongenetic animal effects correlation were close to 1 at adjacent monthly TDMY, with a tendency to diminish as the time between DIM classes increased. The first eigenvector was related to the increase of the genetic response of the milk yield and the second eigenvector was related to the increase of the genetic gains of the persistency but it contributed to decrease the genetic gains for total milk yield. Therefore, using this eigenvector to improve persistency will not contribute to change the shape of genetic curve pattern. If the breeding goal is to improve milk production and persistency, complete sequential eigenvector indices (selection indices composite with all eigenvectors) could be used with higher economic values for persistency. However, if the breeding goal is to improve only milk yield, the traditional selection index is indicated. © 2013 American Dairy Science Association.

Genetic diversity among progenies of Crambe abyssinica Hochst for seed traits

Crambe is an important biofuel crop and its oil has unique traits such as high erucic acid content which can be used as industrial lubricant, corrosion inhibitor as well as ingredient in synthetic rubber manufacturing. Genetic diversity among 70 progenies of Crambe abyssinica Hochst selected from a population of FMS Brilhante cultivar was quantified by multivariate analysis for traits related to germination, thousand grain weight and oil content. There were significant differences among progenies for all traits studied. Estimation of genetic variance and heritability coefficients showed that the variability found in the progeny is more genetic than environmental which enables genetic gains with selection. Heritability coefficient varied from 68 to 79%, except for oil content and number of dead seedlings. Simple correlation analysis showed that germination and vigor were positively correlated, and thousand grain weight and oil content were not correlated with any of the seed traits. Based on multivariate analysis, the progenies could be grouped into 26 clusters. Clusters 1, 2 and 3 had the highest number of progeny with 7, 8 and 6 lineages, respectively. Clusters 21-26 had higher dissimilarity within the cluster with one in each progeny. The trait that most contributed to the cluster was the germination (36.2%) and less contributed was the number of seedlings killed (1.1%). The progenies indicate genetic diversity for seed traits and the selection of superior progenies is possible considering the studied traits. © 2013.

Genetic associations between scrotal circumference and female reproductive traits in Nelore cattle

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Genetic gain in the selection by multi-effects index in open-pollinated progenies of Eucalyptus grandis Hill ex Maiden

In Brazil, Eucalyptus grandis Hill ex Maiden is widely used for commercial reforestation, especially for production of pulp, paper and energy. Its genetic variability is being explored in tree improvement programs for over 30 years. The objective of this work was to estimate genetic parameters and compare genetic gains by multi-effects index in a breeding population of E. grandis. Progeny tests were established using open-pollinated seeds from ten provenances ranging from 153 to 160 progenies established in a completely randomized block design in four sites of Sao Paulo State (Anhembi, Avere Itarare e Pratania). At 24 months of age the traits diameter at breast height (DBH), height (ALT) and volume (VOL) were measured. The individual site analyses indicated significant genetic differences among progenies, height genetic variability and the mean progeny heritability (> 0.70). For joint analyses of sites, significant differences in genotype x environmental interaction effects were detected, showing differences of performance of the progenies in different sites. The Itarare site gave high genetic gains, effective size and genetic diversity. The genetic diversity and low effective size are unviable factors; considering that the progeny tests studied should retain adequate levels of genetic variability in order to be transformed in future seedling seed orchards.

Genetic parameters and trends of morphometric traits of GIFT tilapia under selection for weight gain

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Heritability estimation in early generations of two-way crosses in soybean

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Viabilidade de aplicação da seleção precoce em testes clonais de Eucalyptus spp

Com o objetivo de avaliar a eficiência da seleção precoce em Eucalyptus spp. foram usados dados de dois testes clonais avaliados quanto ao crescimento em altura (ALT), diâmetro à altura do peito (DAP) e volume individual de madeira (VOL) aos 25, 50 e 72 meses de idade. O delineamento experimental nos dois testes clonais foi o de blocos casualizados, com trinta tratamentos (clones), seis repetições, sendo um deles com seis e o outro com dez plantas em linha por parcela, no espaçamento de 3,0 m x 3,0 m. Foi feita a análise de variância para cada caracter e idade. Foram obtidas as estimativas de coeficiente de determinação genotípico e de correlações genotípicas entre os caracteres nas idades juvenis e na idade de rotação. Para verificar a viabilidade da aplicação da seleção precoce, foi simulada a seleção de 30% dos clones nas idades juvenis e na idade de rotação para cada um dos caracteres e idades avaliadas, obtendo-se as estimativas de ganhos genéticos com a seleção direta e indireta. Houve diferenças significativas entre os clones avaliados nos dois experimentos para todos os caracteres e idades. Com base nos resultados obtidos, é possível efetuar a seleção precoce aos 2 anos de idade sobre o caracter DAP em testes clonais de eucalipto.

Estimativas de parâmetros genéticos para características de crescimento em bovinos da raça Canchim utilizando modelos de dimensão finita

Os objetivos neste trabalho foram avaliar diferentes modelos, em relação aos efeitos maternos considerados, para características de crescimento e estimar os parâmetros genéticos para essas características em bovinos da raça Canchim, por meio de análises uni, bi e multicaracterísticas. As características peso ao nascimento, peso ao desmame, pesos padronizados para 12, 18, 24 e 30 meses de idade em machos e fêmeas e peso adulto de fêmeas foram analisadas utilizando-se quatro modelos com os efeitos aleatórios adicionados em sequência. Os efeitos maternos influenciaram os pesos do nascimento aos 2 anos de idade e o peso à desmama foi o mais afetado pelos efeitos maternos. As estimativas de herdabilidade direta obtidas das análises bi e multicaracterísticas foram superiores àquelas obtidas das análises unicaracterísticas. As estimativas de herdabilidade do efeito genético direto obtidas usando análise multicaracterística foram 0,39 para peso ao nascer; 0,31 para peso à desmama; 0,29 para peso aos 12 meses; 0,28 para peso aos 18 meses; 0,26 para peso aos 24 meses; 0,30 para peso aos 30 meses; e 0,38 para peso à idade adulta. As correlações genéticas estimadas entre pesos obtidos em idades jovens com peso à idade adulta foram altas, acima de 0,79. A seleção com base em características de crescimento em qualquer idade pode promover ganhos genéticos moderados no peso corporal de animais da raça Canchim em todas as idades-padrão, inclusive nos pesos ao nascer e à idade adulta das fêmeas. É importante considerar nas análises os pesos prévios à seleção para estimar parâmetros genéticos para pesos após a seleção. A análise multicaracterística é a mais indicada.

Estimativas de parâmetros genéticos de características de crescimento em um rebanho Caracu selecionado para peso ao sobreano

Foram analisados registros de 1.698 animais de um rebanho Caracu selecionado para peso pós-desmame entre os anos 1979 e 2002 com o objetivo de verificar a existência de variabilidade genética aditiva nas características de crescimento e suas interpretações. As características analisadas foram: peso ao nascer (PN), peso padronizado aos 120 dias (P120), peso ao desmame padronizado aos 210 dias (P210), peso de machos ao final da prova de ganho de peso (P378) e ganhos diários do nascimento ao desmame (GND), dos machos na prova de ganho de peso (G112), do desmame ao sobreano em machos (GDSm), peso de fêmeas padronizado aos 550 dias (P550) e ganhos das fêmeas em pastagem do desmame ao sobreano (GDSf), além da altura da garupa a um ano em machos (ALTm) e ao sobreano em fêmeas (ALTf). Os componentes de (co) variâncias, as herdabilidades e as correlações genéticas foram estimados por máxima verossimilhança restrita não-derivativa utilizando-se o software MTDFREML. As estimativas de herdabilidade e os erros-padrão foram iguais a 0,34±0,06; 0,11±0,05; 0,13±0,05; 0,11±0,05; 0,35±0,09; 0,42±0,09; 0,31±0,09; 0,13±0,06; 0,21±0,08; 0,55±0,11; 0,51±0,09 para PN, P120, P210, GND, P378, P550, GDSm, GDSf, G112, ALTm e ALTf, respectivamente. As correlações genéticas entre as características foram de moderadas a altas e positivas, com exceção de algumas correlações com a característica GDSf e o PN. A seleção com base no desempenho do próprio indivíduo, como tem sido realizada, proporciona progresso genético nas características de seleção direta, assim como em algumas características com alta correlação genética.