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)

Genetic correlations between heifer subsequent rebreeding and age at first calving and growth traits in Nellore cattle by Bayesian inference

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

Estimação de parâmetros genéticos para resistência à infecção por IMNV em camarões Litopenaeus vannamei por meio de análise de sobrevivência

The main specie of marine shrimp raised at Brazil and in the world is Litopenaeus vannamei, which had arrived in Brazil in the `80s. However, the entry of infectious myonecrosis virus (IMNV), causing the infectious myonecrosis disease in marine shrimps, brought economic losses to the national shrimp farming, with up to 70% of mortality in the shrimp production. In this way, the objective was to evaluate the survival of shrimps Litopenaeus vannamei infected with IMNV using the non parametric estimator of Kaplan-Meier and a model of frailty for grouped data. It were conducted three tests of viral challenges lasting 20 days each, at different periods of the year, keeping the parameters of pH, temperature, oxygen and ammonia monitored daily. It was evaluated 60 full-sib families of L. vannamei infected by IMNV in each viral challenge. The confirmation of the infection by IMNV was performed using the technique of PCR in real time through Sybr Green dye. Using the Kaplan-Meier estimator it was possible to detect significant differences (p <0.0001) between the survival curves of families and tanks and also in the joint analysis between viral challenges. It were estimated in each challenge, genetic parameters such as genetic value of family, it`s respective rate risk (frailty), and heritability in the logarithmic scale through the frailty model for grouped data. The heritability estimates were respectively 0.59; 0.36; and 0.59 in the viral challenges 1; 2; and 3, and it was also possible to identify families that have lower and higher rates of risk for the disease. These results can be used for selecting families more resistant to the IMNV infection and to include characteristic of disease resistance in L. vannamei into the genetic improvement programs

Quantitative variation in the tropical maize population, ESALQ-PB1

A boa produtividade e os valores intermediários para altura da planta e altura da espiga caracterizam a população de milho ESALQ-PB1 como agronomicamente promissora. São relatadas estimativas de parâmetros para 13 caracteres: altura da planta (PH), altura da espiga (EH), posição relativa da espiga (EP), comprimento do pendão (TL), peso do pendão (TW), número de ramificações do pendão (TB), peso de espigas (EW), peso de grãos (GW), comprimento da espiga (EL), diâmetro da espiga (ED), número de fileiras de grãos (RN), número de grãos por fileira (KR) e prolificidade (PR). Os resultados se referem a um único ambiente (um local e um ano). Foi detectada variação genética para todos os caracteres, e são apresentadas estimativas da variância genética aditiva. Os coeficientes de herdabilidade (indivíduos) variaram de 0,14 a 0,72 e foram considerados altos para PH, EH e TB; intermediários para EP, TL, TW, EL e ED, e baixos para EW, GW, KR e PR. O coeficiente de herdabilidade para médias de progênies mostrou aproximadamente a mesma tendência, variando de 0,40 a 0,75. O maior ganho esperado por seleção foi para TB (27% por ciclo) sob seleção massal e para TW (16,4%) por seleção entre progênies; o menor ganho esperado foi para ED, tanto por seleção massal (1,9%) como por seleção entre progênies (2,9%). Coeficientes de correlação aditiva (rA) 0.5

The adaptive potential of a plant pathogenic fungus, Rhizoctonia solani AG-3, under heat and fungicide stress

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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)

Variação Genética e ganho esperado na seleção de progênies de Pinus caribaea var. caribaea em Selvíria, MS

The present research has proposed to estimate the genetic variation of growth traits and to estimate the expected gain by multi-effect index (MEI), in order to transform a Pinus caribaea var. caribaea progeny trial into a seedling seed orchard. The progeny trial was set up in 1989, in Selviria, MS, Brazil, using a 10 x 10 triple lattice design, with 99 progenies and a commercial control, with linear plots of ten plants, by the 3 x 3 m spacing between plants and rows. Total plant height, diameter at breast height (Dbh), wood volume, stem form, wood density at breast height, and survival were the evaluated quantitative traits. The trial was measured through 14, 15, and 16 years old. The 50% intensity of thinning at 14.3 years old was done. No significant was the genetic variation of different traits. Heritability estimates have presented low magnitude with low variation by the different ages. The application of MEI to DBH, at two years after thinning, resulted in higher gains than the selection of within and among progenies. The best selection strategy to obtain higher gains and to keep genetic diversity is to select until five plants per progenies.

Population parameters in Brazilian Thoroughbred

The information in this study has been provided by the Brazilian Association of Racehorse Breeders [Associação do Brasileira dos Criadores do Cavalo de Corrida (ABCCC)]. It can be found in the files on the CD-ROM developed by the ABCCC in 1999. A total of 5008 finishing time records related to 2545 winning horses that ran in the classical calendar on Brazilian hippodromes during 25 years (197498) were analysed. There were a total of 9949 horses on the relationship matrix. The variance components were estimated using the multiple-trait derivate-free restricted maximum likelihood (MTDFREML) program, for an animal model. Generation intervals were higher in the maternal side (10.91 years) than in the paternal one (10.41 years). The estimates for genetic permanent environmental and phenotypic variances and heritability were 0.291, 0.161, 3.486 and 0.08, respectively. The phenotypic standard deviation for time in races was 1.86729 s. Genetic time trend on Thoroughbred races in Brazil was small and could be accelerated if selection considered the trait time effectively. With respect to the animal's country of birth, the results show that there has been an intense participation of foreign animals in breeding Brazilian Thoroughbreds.

Genetic parameters of racing performance traits of Quarter horses in Brazil

The data used in the present study were recorded at the Jockey Club of Sorocaba for 5094 racing performance of 1350 Quarter Horses at the Paulista Race Track of Sorocaba, state of São Paulo, Brazil, from 1991 to 1997. The considered traits were time and final rank. The model used in analysis included random animal and permanent environmental effects, and race, sex, age and origin as fixed effects. The variance and covariance components were estimated by the restricted maximum likelihood for an animal model, using the derivative-free process method and the MTDFREML software. For the time, heritability was 0.17 (0.05), while estimate of repeatability 0.55 (0.05). The lower heritability for the final rank, 0.13 (0.04), indicate that this trait is not the most appropriate one for inclusion in programs of Quarter horse selection in Sorocaba racetrack. The repeatability estimate for rank was 0.44 (0.04) and the genetic correlation between this trait and time was 0.99.

Genetic and environmental parameters for racing time at different distances in Brazilian Thoroughbreds

The aim of the present study was to investigate genetic parameters for racing time in Thoroughbred horses racing at distances between 1000 and 1600 m subdivided into 100-m intervals. The data provided by TURFETOTAL Ltda comprised races that occurred in the Gavea and Cidade Jardim race tracks over a period of 11 years (1992-2002) and consisted of 32 145 races and 238 890 time records. The variance components necessary to obtain the heritability and repeatability estimates of the traits studied were estimated with the MTDFREML program, and animal age at race (3 years old or younger, 4, 5 and older than 5 years), sex (male and female), number of races (1-32 145), and postposition at start (1-11) as fixed effects, and animal and permanent environmental random effects were included in a one-trait animal model. Males were significantly superior to females at all distances. Excluding the 1100 m distance, animals 4 years of age were significantly faster than the mean of the other ages for all distances analysed. Horses older than 5 years showed a significantly lower performance than the mean of the other ages for all distances analysed, except for the 1100 m. Postpositions one and two did not differ significantly from one another for any of the distances analysed. These two inner positions both together varied from the other positions depending on race length. The components of additive genetic and permanent environmental variance varied in a similar way, tending to decrease with increasing racing distance, and the other temporary environmental variance almost doubled from 1000 to 1600 m. As was the case for the additive genetic and environmental variances, heritability and repeatability estimates tended to decrease with increasing distance, indicating that selection based on racing time will be less successful when the racing distance increases.

Genetic and environmental factors that affect the best time of Thoroughbred horses in Brazil

On the basis of information provided by the Brazilian Association of Race Horse Breeders, we analysed the racing performance of 947 Thoroughbred horses in races held from 1985 to 1992. The performance was evaluated using the best, time of the animals. The variance component was obtained by the derivative-free restricted maximum likelihood method, and the model used contained fixed effects of the racing month and year, sex, race track, track condition, animal age, number of competitors in race, and distance, and the random animal effect. The low heritability estimate obtained (0.12) indicates that selection based on animal phenotypic value must induce small genetic changes in this trail.

Genotype by environment interaction for 450-day weight of Nelore cattle analyzed by reaction norm models

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Estudo de simulação de modelos lineares mistos com distribuição normal contaminada no melhoramento genético animal

Objetivou-se com esse trabalho comparar estimativas de componentes de variâncias obtidas por meio de modelos lineares mistos Gaussianos e Robustos, via Amostrador de Gibbs, em dados simulados. Foram simulados 50 arquivos de dados com 1.000 animais cada um, distribuídos em cinco gerações, em dois níveis de efeito fixo e três valores fenotípicos distintos para uma característica hipotética, com diferentes níveis de contaminação. Exceto para os dados sem contaminação, quando os modelos foram iguais, o modelo Robusto apresentou melhores estimativas da variância residual. As estimativas de herdabilidade foram semelhantes em todos os modelos, mas as análises de regressão mostraram que os valores genéticos preditos com uso do modelo Robusto foram mais próximos dos valores genéticos verdadeiros. Esses resultados sugerem que o modelo linear normal contaminado oferece uma alternativa flexível para estimação robusta em melhoramento genético animal.

Avaliação genética multirracial para ganho de peso pré-desmama em bovinos de uma população composta

Objetivou-se neste trabalho estudar modelos com efeitos não-aditivos diretos e maternos em uma população composta em clima tropical, tentando minimizar esses efeitos para obtenção dos valores genéticos dos animais avaliados. Foram utilizados dados de animais de uma população composta, por meio da comparação de três modelos que incluíram os efeitos fixos de grupo contemporâneo, ordem de parto e heterose direta e materna e os efeitos aleatórios de efeito genético aditivo direto e materno. As análises foram realizadas em duas etapas; na primeira foram estudadas as estimativas dos efeitos raciais e de heterose individual e materna e na segunda etapa, calculadas as variâncias, herdabilidades e os valores genéticos dos animais. O efeito materno, quando não foi considerado no modelo, pareceu superestimar o efeito aditivo racial. Os efeitos aditivos raciais, racial materno e de heterose individual e materna influenciaram significativamente o ganho médio diário no pré-desmame, obtendo-se diferentes estimativas entre os tipos biológicos. Considerando o arquivo de dados corrigidos para os efeitos não-aditivos diretos e maternos, as herdabilidades direta e materna foram de 0,22 e 0,20, respectivamente. Os efeitos racial materno e de heterose individual e materna foram importantes fontes de variação para o ganho médio diário no pré-desmame e devem ser considerados durante a avaliação genética de uma população multirracial.

Genetic parameters for stayability in Murrah buffaloes

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)