The main revenue source for beef cattle farmers is the price they are awarded for carcasses based on carcass value (i.e., carcass weight, conformation and fat score) which is influenced by genetic and environmental factors (e.g., herd management). In order to improve profitability, accurate means of evaluating and improving both sets of factors influencing carcass trait performance are necessary. This would entail optimal management of genetic resources and herd practices. Furthermore, access to a large international germplasm pool would facilitate faster genetic gain. The objective of this thesis was to generate tools for the enhancement of carcass trait genetic and herd management evaluations both at a national and international level. The data used in the thesis originated from the Irish and UK national cattle databases and consisted of 336,944 Irish and 147,876 UK cattle of multiple beef and dairy breeds from 9,572 Irish and 3,385 UK commercial herds. Livestock mature at different rates depending on a number of factors including the genetic background; therefore, the optimum age at which to slaughter the progeny of different sires may differ. Chapter 2 examined sire level genetic profiles for three carcass traits (carcass weight, conformation and fat score) in cattle using data from the Republic of Ireland. Variance components for each trait across age at slaughter were estimated using sire random regression models. Heritability estimates of carcass traits across ages at slaughter varied depending on gender (heifers, steers, young bulls) and the trait in question, and ranged from 0.08 (± 0.02) to 0.34 (± 0.02) for carcass weight, from 0.24 (± 0.02) to 0.42 (± 0.02) for conformation score and from 0.16 (± 0.03) to 0.40 (± 0.02) for fat score. Genetic correlations between traits across ages at slaughter were all significantly less than unity, indicating that different genetic mechanisms control these traits across life. The results from chapter 2 show that genetic variability in the progeny growth trajectory of sires exists and that this variability in the growth profiles of sires for carcass traits may be exploited in breeding programmes. As carcass traits are a function of both the genetics of the animal and the environment in which the animal is reared, chapter 3 aimed to quantify the contribution of the herd environment to the same three beef carcass traits, with particular emphasis on generating finishing herd-specific profiles for carcass traits across different ages at slaughter. The data analysed in chapter 3 was from animals slaughtered in UK abattoirs. Genetic and finishing-herd-year of slaughter parameters were generated using random regression analysis. Across slaughter age and gender, the proportion of phenotypic variance accounted for by finishing-herd-year of slaughter variance was between 30.83%-71.48% for carcass weight, 21.38%-26.29% for conformation score and between 10.88%-44.04% for fat score. These parameters indicate that the finishing herd environment is an at least equally important contributor to carcass trait variability as the genetic background of animals, and amenable to improvement with appropriate management practices. The final study of the thesis was to investigate the feasibility of across-country carcass trait genetic evaluations. Examination of the level of genetic connectedness between Ireland and the UK found 225 distinct bulls common to both countries. These common bulls were related to 80,707 Irish and 23,162 UK animals with carcass records in each population. Genetic correlations for carcass traits between Ireland and the UK were almost unity, ranging from 0.92 (± 0.31) for fat score to 0.96 (± 0.17) for carcass weight, indicating that the carcass traits recorded in both countries are genetically essentially equivalent. These strong genetic correlations between carcass traits in both countries enabled the direct pooling of carcass data for the purpose of across-country genetic evaluations (breeding value estimation). An increased rate of genetic gain for carcass traits per generation was predicted from across-country selection compared to within country selection ranging from 2% (conformation score in Ireland) to 33.77% (conformation score in the UK). This improved gain was primarily due to greater intensity of selection and somewhat more accurate estimated breeding values when carcass records and pedigree information from both countries were combined. The results presented in this thesis demonstrate that routinely collected abattoir data in Ireland and the UK can be exploited to produce additional selection and on-farm management tools. The results also show that access to across-country carcass trait genetic evaluations would allow UK and Irish beef farmers to make more informed decisions on the selection of seed stock needed to increase genetic gain and profits. Outcomes of this thesis pave the way to improvements in national carcass traits genetic evaluations in Ireland and the UK based on appropriate age at slaughter and also demonstrate the feasibility of across-country carcass trait genetic evaluations between Ireland and the UK. The scope for further areas of research includes the identification of specific management practices for optimal herd performance for carcass traits. Additionally, across-country carcass trait genetic evaluations based on random regression models across different ages at slaughter would also be of benefit to beef producers in Ireland and the UK. Finally, the viability of across-country genetic evaluations for additional carcass traits, such as carcass cut weights should be explored.

Resumo: Foram estimados parâmetros genéticos para a produção de leite, gordura e proteína no dia do controle de primeiras lactações de búfalas leiteiras por meio de análises uni e multicaracterística de regressão aleatória. Para os modelos de regressão aleatória unicaracterística foram analisadas as 1.433 primeiras lactações de búfalas. Para as características em estudo, foram considerados nos modelos utilizados, os efeitos aleatórios genético aditivo, de ambiente permanente e o residual. Como efeitos fixos, foram considerados o grupo contemporâneo e o número de ordenha (1 ou 2 ordenhas). Os efeitos linear e quadrático da covariável idade da vaca ao parto e a curva média de lactação da população, estão modelados por polinômios ortogonais de Legendre de terceira ordem. Os efeitos aleatórios genético aditivo e de ambiente permanente foram estimados por meio de regressão aleatória sobre polinômio ortogonais de Legendre de terceira à sexta ordem. Os resultados indicam que são requeridos polinômios de Legendre de baixa ordem para modelar a estrutura de (co)variância genética e de ambiente permanente. As estimativas de herdabilidade das características em estudo foram moderadas, o que poderia ajudar no processo de seleção dos animais para obtenção de ganhos genéticos. As estimativas das correlações genéticas foram altas entre controles, indicando que seja qual for o critério de seleção adotado, ganhos genéticos indiretos são esperados em toda a curva de lactação. Para o modelo de regressão aleatória multivariada foi analisado o mesmo banco de dados e as mesmas pressuposições do modelo unicaracaterística. No que se refere à modelagem dos efeitos aleatórios, utilizouse, em todas as características, polinômios de Legendre de terceira ... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Genetic parameters for milk, fat and protein yields in the test day were estimated for the first lactations of dairy buffaloes by using single- and multiple-trait random regression analyses. To the single-trait analyses were analyzed 1,433 first lactations. The models included as random effects: additive genetic, permanent environment and residual and as fixed effects: contemporary group, number of milkings (one or two), linear and quadratic effects of the covariable age of the buffalo at birth and mean lactation curve of the population, modeled using Legendre orthogonal polynomials of third order. The random regression effects of genetic and permanent environment were estimated by random regression with Legendre orthogonal polynomials from third to sixth orders. The results indicate that low order polynomials are required to model the structure of genetic and permanent environment (co)variances. The heritability estimates of the traits studied were moderated, it permits to do selection of animals to obtain genetic gain. The genetic correlation estimates were high among test-days, indicating that the selection aims may be different, but indirect genetic gain for all the lactation curve was expected. To the model of multiple-trait random regression, the same data was analyzed, with the same presuppositions of the single-trait model. To model the random effects, Legendre polynomials of third and fourth order were used, to genetic effects and permanent environment, respectively. The residual variances were modeled considering four residual classes grouped as: 1, 2-3, 4-8, 9-10 months of lactation. The results indicate that the heritabilities estimates of the traits presented enough genetic variance to be selected. The estimates of the variance components may be used to implement a BLUP evaluation in a Brazilian buffalo population. The genetic correlations among test-days for a trait ... (Complete abstract click electronic access below) / Orientador: Humberto Tonhati / Coorientador: Lucia Galvão de Albuquerque / Coorientador: Milthon Muñoz Berrocal / Banca: Henrique Nunes Oliveira / Banca: Danísio Prado Munari / Banca: Maria Eugênia Zerlotti Mercadate / Banca: Leonardo de Oliveira Seno / Doutor

The purpose of this study was to examine whether child temperament, parent personality, and the interaction between the two would predict anxiety/depressive problems, and also whether the presence of positive factors would be related to child anxiety/depressive problems. It was also hypothesized that child mood would be predictive of symptoms of anxiety and depression, even after accounting for heritability. Participants were 106 5-year-old twin pairs and their parents, who completed questionnaires and a parent-child interaction. As hypothesized, child negative mood and parent personality were significant predictors of anxiety/depressive problems. However, their interaction was not significant. For children in the negative mood group, as their level of family conflict decreased, their score on anxiety/depression also decreased, providing evidence that low family conflict is protective. Results also revealed that anxiety/depression is heritable and that child mood was significant in predicting symptoms of anxiety and depression even after first accounting for heritability.

This study investigated the etiology of preschoolers’ somatic symptoms and internalizing problems, using a twin sample. A specific focus was placed on the genetic (i.e., DRD4 and 5-HTTLPR) and environmental (i.e., SES, household chaos, family conflict, and maternal emotional stability) factors that were hypothesized to be associated with these problems. This project also explored the possible gene-environmental interactions (GxE) that may exist among these contributors. It was hypothesized that children who are at greatest risk due to their genotype, environment, or a combination of the two would display elevated somatic symptoms and internalizing problems, compared to children who were less at-risk due to these factors. Data from 252 families included in the Southern Illinois Twins/Triplets and Siblings Study (SITSS) at age 5 were examined. Results indicated a significant DRD4 x household chaos interaction predicting preschoolers’ somatic symptoms, demonstrating that children with the DRD4-7r genotype exhibited less somaticizing in highly chaotic homes. Additionally, 5-year-old internalizing problems were significantly predicted by the cumulative environmental risk factor created (i.e., top 15% of scores for each environmental variable in the current sample) and marginally by the additive genotypic risk factor (i.e., a summation of the DRD4 and 5-HTTLPR “risk” scores). These results provide additional insight into the factors that may place children at greater risk for somatic symptoms and internalizing problems.

Made available in DSpace on 2014-06-11T19:26:06Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-07-27Bitstream added on 2014-06-13T19:54:01Z : No. of bitstreams: 1 irano_n_me_jabo.pdf: 187304 bytes, checksum: 9f2cf22f2fa39eab86ecdfc75843adfe (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Objetivou-se com este trabalho estimar parâmetros genéticos para produção de leite, habilidade de permanência da vaca no rebanho e ocorrência de mastite clínica de vacas da raça Holandesa, bem como estudar as associações genéticas entre elas, com intuito de fornecer subsídios para a avaliação genética destas características. Foram analisados dados de 5.090 vacas da raça Holandesa que pariram no período de 1991 a 2010, pertencentes à Agropecuária Agrindus S.A.. Foram feitas duas análises multicaracterísticas, uma contendo as características produção de leite acumulada até 305 dias na primeira lactação (PL1), habilidade de permanência das vacas no rebanho (HP) até a terceira lactação e ocorrência de mastite clínica (OM) e, a outra, produção de leite acumulada até 305 dias (P305), HP e OM, ambas sob modelos animal e considerando as três primeiras lactações como medidas repetidas para P305 e OM. Os componentes de covariância foram obtidos por abordagem Bayesiana, utilizando o programa THRGIBBS1F90. As estimativas de herdabilidade, obtidas pela análise multicaracterísticas com a PL1, foram de 0,19; 0,28 e 0,13 para a PL1, HP e OM, respectivamente, enquanto que, na análise multicaracterísticas com a P305, as estimativas foram de 0,19; 0,31 e 0,14, respectivamente. As correlações genéticas foram de 0,38 entre PL1 e HP, 0,12 entre PL1 e OM e -0,49 entre HP e OM, em análise multicaracterísticas com a PL1 e, de 0,66 entre P305 e HP, -0,25 entre P305 e OM e - 0,52 entre HP e OM, em análise multicaracterísticas com a P305 / The objective of this study was to estimate genetic parameters for milk yield, stayability and the occurrence of clinical mastitis in Holstein cows, as well as studying the genetic relationship between them, in order to provide subsidies for the genetic evaluation these traits. Records from 5,090 Holstein cows with calving varying from 1991 to 2010, belonging to the Agropecuária Agrindus S.A. Two standard multivariate analyses were carried out, one containing the trait of accumulated 305 day milk yields in first lactation (MY1), stayability (SA) to the third lactation and clinical mastitis (CM) and the other, accumulated 305 day milk yields (MY), SA and CM, considering the first three lactations as repeated measures for MY and CM. The covariance components were obtained by Bayesian approach using the program THRGIBBS1F90. The heritability estimates obtained by multivariate analysis with MY1, were 0.19, 0.28 and 0.13 for MY1, SA and CM, respectively, whereas the multivariate analysis with the MY, the estimates were 0.19, 0.31 and 0.14, respectively. The genetic correlations between MY1 and SA, MY1 and CM, SA and CM, respectively, were 0.38, 0.12, and -0.49. The genetic correlations between MY and SA, MY and CM, SA and CM, respectively, were 0.66, -0.25, and -0.52

Made available in DSpace on 2014-06-11T19:26:07Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-08-30Bitstream added on 2014-06-13T20:33:49Z : No. of bitstreams: 1 magalhaessilva_lc_me_jabo.pdf: 1240622 bytes, checksum: 43e0525da56c6c05bc0304559d7a5c2f (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Esta pesquisa teve como objetivo geral ampliar os estudos sobre a variabilidade genética para mortalidade pré (Mpre) e pós-natal (Mpos) em bovinos da raça Nelore, estimando parâmetros genéticos dessas características. Os dados analisados foram provenientes de fêmeas nascidas entre 1984 e 1995, pertencentes à Agropecuária Jacarezinho Ltda, localizada no município de Valparaíso. As variáveis Mpre e Mpos se caracterizam por expressão binária, considerando-se duas condições, para Mpre: 1= sucesso, para os bezerros que conseguiram nascer e 0= falha, para bezerros que não conseguiram chegar ao final da gestação; e para Mpos: 1= sucesso, para bezerros que estavam presentes na desmama e 0= falha, para os que apresentaram peso ao nascer (PN), mas não conseguiram sobreviver até a desmama. O grupo contemporâneo (GC) foi considerado como efeito aleatório no modelo. Para Mpre o GC foi definido como: ano e fazenda no inicio da estação de monta, ano e fazenda de nascimento da vaca e estação de monta. Como efeito fixo foi considerado a idade da fêmea ao inicio da estação de monta em classes (variando de 1 a 13 anos). Para Mpos o GC foi definido como: bezerros do mesmo sexo, fêmeas nascidas e paridas na mesma fazenda e ano e grupo de manejo ao nascimento das fêmeas, foram considerados como efeitos fixos a idade da vaca ao parto em classes (variando de 2 a 9 anos), e como covariável o PN do bezerro (efeito linear e quadrático). Os componentes de variância foram estimados em análise unicaracterística utilizando-se a inferência Bayesiana pelo programa THRGIBBS1F90. Os intervalos de amostragem foram pelo pacote estatístico “BOA” (“Bayesian Output Analysis”), do programa R (R DEVELOPMENT CORE TEAM). A taxa de Mpre, encontrada no conjunto de dados foi de 2,0% e a estimativa de herdabilidade direta para Mpre, com base na característica da fêmea foi de magnitude moderada... / The aims of this research were to increase the knowledge about genetic variability of stillbirth (Mpre) and postnatal mortality (Mpos) in Nellore cattle through estimates of the genetic parameters for these traits. Mpre and Mpos were assessed as a cow and calf traits, and sire and animal model were compared. Datasets were obtained from females born between 1984 and 1995 on the Agropecuaria Jacarezinho Ltda. Mpre and Mpos are characteristics of binary expression, considering, for Mpre: 1= success, for calves that could be born, and failure (0), for those failed to reach in the end of pregnancy. For Mpos: success (1) for calves those were present at weaning, and failure (0): for those who had birth weight (PN), but did not survive weaning. The contemporary group (CG) was considered as the random effect in the model. For Mpre the GC was defined by year and farm at start of the breeding season of the cow, year and farm of birth of the cow and breeding season; the fixed effect was the age of the cow at beginning of breeding season (in classes, ranging from 1-13 years). For Mpos the GC was defined by calves of the same sex, cows that were born and calved on the same farm, year and handling group at calving; the fixed effects was age of calving (in classes, ranging 2-9 years) and, as covariable, the PN of calf (linear and quadratic). Variance components were estimated in univariate analysis using the Bayesian inference by the program THRGIBBS1F90. The sampling intervals were defined by statistical package “BOA” (Bayesian Output Analysis) included in program R (R Development Core Team, 2008). The rate of Mpre found in the dataset was 2.0%. The estimate of direct heritability for Mpre, based on the female´s traits was moderate (0.22), indicating moderate genetic gain in the population and good prospects for selection response. Estimates of direct heritability (0.01) and maternal total... (Complete abstract click electronic access below)

Made available in DSpace on 2014-06-11T19:32:15Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-05-31Bitstream added on 2014-06-13T20:43:07Z : No. of bitstreams: 1 aspilcuetaborquis_rr_dr_jabo.pdf: 608014 bytes, checksum: fec77d6e9cf690a6db8e92476a753c54 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Foram estimados parâmetros genéticos para a produção de leite, gordura e proteína no dia do controle de primeiras lactações de búfalas leiteiras por meio de análises uni e multicaracterística de regressão aleatória. Para os modelos de regressão aleatória unicaracterística foram analisadas as 1.433 primeiras lactações de búfalas. Para as características em estudo, foram considerados nos modelos utilizados, os efeitos aleatórios genético aditivo, de ambiente permanente e o residual. Como efeitos fixos, foram considerados o grupo contemporâneo e o número de ordenha (1 ou 2 ordenhas). Os efeitos linear e quadrático da covariável idade da vaca ao parto e a curva média de lactação da população, estão modelados por polinômios ortogonais de Legendre de terceira ordem. Os efeitos aleatórios genético aditivo e de ambiente permanente foram estimados por meio de regressão aleatória sobre polinômio ortogonais de Legendre de terceira à sexta ordem. Os resultados indicam que são requeridos polinômios de Legendre de baixa ordem para modelar a estrutura de (co)variância genética e de ambiente permanente. As estimativas de herdabilidade das características em estudo foram moderadas, o que poderia ajudar no processo de seleção dos animais para obtenção de ganhos genéticos. As estimativas das correlações genéticas foram altas entre controles, indicando que seja qual for o critério de seleção adotado, ganhos genéticos indiretos são esperados em toda a curva de lactação. Para o modelo de regressão aleatória multivariada foi analisado o mesmo banco de dados e as mesmas pressuposições do modelo unicaracaterística. No que se refere à modelagem dos efeitos aleatórios, utilizouse, em todas as características, polinômios de Legendre de terceira... / Genetic parameters for milk, fat and protein yields in the test day were estimated for the first lactations of dairy buffaloes by using single- and multiple-trait random regression analyses. To the single-trait analyses were analyzed 1,433 first lactations. The models included as random effects: additive genetic, permanent environment and residual and as fixed effects: contemporary group, number of milkings (one or two), linear and quadratic effects of the covariable age of the buffalo at birth and mean lactation curve of the population, modeled using Legendre orthogonal polynomials of third order. The random regression effects of genetic and permanent environment were estimated by random regression with Legendre orthogonal polynomials from third to sixth orders. The results indicate that low order polynomials are required to model the structure of genetic and permanent environment (co)variances. The heritability estimates of the traits studied were moderated, it permits to do selection of animals to obtain genetic gain. The genetic correlation estimates were high among test-days, indicating that the selection aims may be different, but indirect genetic gain for all the lactation curve was expected. To the model of multiple-trait random regression, the same data was analyzed, with the same presuppositions of the single-trait model. To model the random effects, Legendre polynomials of third and fourth order were used, to genetic effects and permanent environment, respectively. The residual variances were modeled considering four residual classes grouped as: 1, 2-3, 4-8, 9-10 months of lactation. The results indicate that the heritabilities estimates of the traits presented enough genetic variance to be selected. The estimates of the variance components may be used to implement a BLUP evaluation in a Brazilian buffalo population. The genetic correlations among test-days for a trait ... (Complete abstract click electronic access below)

Made available in DSpace on 2014-06-11T19:32:16Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-06-23Bitstream added on 2014-06-13T20:03:33Z : No. of bitstreams: 1 silveira_ft_dr_jabo.pdf: 282729 bytes, checksum: e8b76faa03114db3405ff9f319c85596 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O complexo do enfezamento, que abrange os enfezamentos pálido (Spiroplasma kunkelli) e vermelho (Mayze bushy stunt phytoplasma) é causado por patógenos pertencentes à classe dos molicutes e transmitido pela cigarrinha Dalbulus maidis. Por ser o único hospedeiro dessa doença e do seu vetor e transmissor, têm-se observado elevados prejuízos em híbridos suscetíveis. O desenvolvimento de cultivares com resistência genética é a alternativa mais eficiente para o controle dessa doença. Para isso é necessário conhecer a herança da resistência para direcionar os métodos de seleção a serem empregados e os trabalhos de introdução da resistência em germoplasmas suscetíveis. Objetivando compreender a herança da resistência aos enfezamentos em milho, foram realizados trabalhos com linhagens de milho, mediande análise dialélica e médias de gerações. Para a análise dialélica foram utilizadas doze linhagens endogâmicas de milho, representada por quatro linhagens resistentes e oito linhagens suscetíveis, cruzando-se as resistentes com as suscetíveis em esquema de dialélico parcial. Para as análises de médias de gerações foram cruzadas três linhagens resistentes e quatro suscetíveis para a obtenção das gerações F1, F2, RCP1 e RCP2. Os trabalhos foram conduzidos em Jaboticabal (SP) e Guaíra (SP), avaliando, no estádio fenológico R3, a incidência de enfezamento. Efeitos significativos para CGC e CEC foram obtidos, indicando que, no controle do caráter enfezamentos, estão envolvidos tanto os efeitos aditivos como os de dominância. Análises de médias de gerações revelaram a presença de poucos genes envolvidos com o controle da resistência, com predominância de efeitos aditivos, o que permite a seleção de genótipos resistentes. As linhagens PH1894, PH1977 e PH1173-1 poderão ser utilizadas como fontes de resistência em futuras combinações híbridas. / The corn stunt complex, that embraces the pale corn stunt (Spiroplasma kunkelli) and red (Mayze bushy stunt phytoplasma) it is caused by patógenos belonging to the class of the molicutes and transmitted by the cicada Dalbulus maidis. For being the only host of that disease and of your vector and transmitter, high damages have been observing in hybrid susceptible. The development of you cultivate with genetic resistance it is the most efficient alternative for the control of that disease. For that it is necessary to know the inheritance of the resistance to address the selection methods they be her used and the works of introduction of the resistance in susceptible germoplasmas. Aiming at to understand the inheritance of the resistance to the corn stunt, works were accomplished with corn lineages, trough analysis dialélica and averages of generations. For the analysis dialélica twelve inbred lines of corn were used, represented by four resistant inbred lines and eight susceptible inbred lines, crossing the resistant ones with the susceptible ones in outline of partial dialélico. For the analyses of averages of generation three resistant inbred lines and four were crossed susceptible for the obtaining of the generations F1, F2, RCP1 and RCP2. The works were led in Jaboticabal (SP) and Guaíra (SP), evaluating, in the stadium fenológico R3, the corn stunt incidence. Significant effects for CGC and CEC were obtained, indicating that, in the control of the character corn stunt, they are involved as much the addictive effects as the one of dominance. Analyses of averages of generations revealed the presence of few genes involved with the control of the resistance, with predominance of addictive effects, what allows the selection of resistant genotypes. The inbred lines PH1894, PH1977 and PH1173-1 can be used as resistance sources in future hybrid combinations.

Made available in DSpace on 2014-06-11T19:33:32Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-12-17Bitstream added on 2014-06-13T20:05:37Z : No. of bitstreams: 1 pereira_mc_dr_jabo.pdf: 621440 bytes, checksum: 260b1b949ce4be72f4da602866530c0c (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / A otimização da eficiência econômica dos rebanhos bovinos está diretamente relacionada à vida reprodutiva das matrizes. Assim, espera-se que o incremento na taxa de reconcepção de fêmeas primíparas leve a um aumento produtividade da pecuária de corte. O trabalho teve o objetivo de avaliar a reconcepção de fêmeas primíparas de um rebanho comercial da raça Nelore, utilizando inferência Bayesiana, modelo de sobrevivência e Método ℜ, com intuito de verificar a possibilidade de utilizar a característica como critério de seleção. Os registros analisados são provenientes de fêmeas da raça Nelore, nascidas entre 1984 e 2002, e pertencentes ao arquivo zootécnico da Agropecuária Jacarezinho Ltda., empresa que se dedica à bovinocultura de corte, localizada no noroeste do Estado de São Paulo, Brasil. As estimativas de herdabilidade foram iguais a 0,15; 0,18; e 0,07 utilizando inferência Bayesiana, modelo de sobrevivência e Método ℜ, respectivamente. De modo geral, os resultados indicaram dificuldade em se obter progresso genético para esta característica por meio de seleção. Entretanto, mesmo pequenos aumentos nos índices de reconcepção de novilhas podem contribuir para a eficiência econômica da atividade, dado os baixos índices descritos atualmente no cenário nacional. Modificações no ambiente em que as novilhas foram criadas podem elevar ou diminuir consideravelmente a taxa de reconcepção do rebanho. As estimativas de correlação genética entre a reconcepção de fêmeas primíparas e o peso ao sobreano e o perímetro escrotal foram -0,66 e -0,07, respectivamente. Assim, a seleção para peso ao sobreano poderá levar a uma diminuição na taxa de reconcepção de fêmeas primíparas da raça Nelore. A utilização do perímetro escrotal como critério de seleção em programas de melhoramento animal não causou mudanças genéticas na reconcepção de fêmeas primíparas. / The optimization of the economic efficiency of cattle herds is directly related to the reproductive life of dam. Thus, the increase in the heifer subsequent rebreeding rate will lead to greater productivity of the livestock production. The objective of this study was to evaluate the heifer subsequent rebreeding in a commercial herd of the Nelore cattle, using Bayesian inference, survival model and the Method ℜ, in order to verify the possibility of using this trait as selection criterion. The records analyzed are from Nelore cattle females, born between 1984 and 2002, belonging to Agropecuária Jacarezinho Ltda., a company which works with beef cattle and is located in the northwest of the State of São Paulo, Brazil. The estimates of heritability were 0.15, 0.18 and 0.07 when using Bayesian inference, the survival model and the Method ℜ, respectively. In general, these results indicate that it is difficult to obtain genetic progress by selection for this trait. However, small increases in the heifer subsequent rebreeding can contribute to the economic efficiency of the activity, given the low subsequent rebreeding rates in the national scene. Changes in the environment where the heifers were bred can considerably increase or decrease the subsequent rebreeding rates the herd. The genetic correlation between the heifer subsequent rebreeding and the yearling weight was -0.66. Thus, selection for yearling weight may reduce the rates of rebreeding subsequent of heifers in Nelore cattle. The genetic correlation between the heifers subsequent rebreeding and the scrotal circumference was - 0.07. The use of the scrotal circumference as criterion of selection in programs of animal improvement will not cause any genetic changes in the rebreeding subsequent of heifers.

Trees and forests are under increasing threat from pathogens which cause huge economic and ecological damage. The unprecedented global movement of pathogens into new areas creates novel pathosystems, while the changing climate affects the dynamics of endemic pathosystems. Co-evolution within endemic pathosystems affects the genetic composition of hosts and pathogens. Spatial heterogeneity in pathogen pressure leads to genetic variation in disease-related traits among host populations. In contrast, novel hosts or populations are expected to be highly susceptible to exotic pathogens as there has been no evolution of defence responses. Host response to disease can therefore be an indicator of a novel or endemic pathosystem. The long term resilience of forests to pathogens depends on the adaptive capacity of both the host and pathogen species. Establishing the extent of genetic and phenotypic variation within both the host and pathogen is therefore fundamental in understanding past, current and future pathosystem dynamics. The most significant current threat to Scots pine (Pinus sylvestris) is Dothistroma needle blight (DNB) caused by the foliar pathogen Dothistroma septosporum which is assumed to be exotic to Great Britain. This study aimed to increase understanding of the genetic and phenotypic variation in this pathosystem. Results from this study show that there are high levels of variation in the Dothistroma – Pinus pathosystem. Genetic variation, elucidated using neutral genetic markers, mating type specific markers and in vitro analysis of phenotypic variation in D. septosporum collected from Scottish pinewoods, was found to be high: there was high allelic diversity, particularly within plantation forests outside the native pinewood range, and high phenotypic plasticity in response to different temperature treatments. Both mating type idiomorphs were found in one forest which demonstrates their potential for sexual as well as asexual reproduction. There is also tentative evidence from this study that the pathogen is either introduced to Great Britain or that endemic pathogen populations have been augmented with introduced pathogens. Artificial and natural inoculations of native Scots pine provenances with D. septosporum indicate that there is considerable variation in susceptibility to DNB across the native range in Scotland and that variation in this trait is both highly heritable and evolvable. Furthermore, provenance mean susceptibility to DNB is negatively and significantly associated with water-related variables at site of origin, a finding that is potentially indicative of a co-evolutionary history between host and pathogen. Genetic differences among individuals which are ‘resistant’ or ‘susceptible’ to DNB were identified in Pinus radiata for which there has been extensive research in this pathosystem, by comparing the transcriptome sequences of the two phenotypic groups. Nearly half of the genetic differences identified among phenotypes were found in genes with a putative defence function. In conclusion, native Scots pine provenances contain the necessary heritable genetic diversity to evolve a decrease in their susceptibility to D. septosporum through natural selection in response to elevated prevalence of this pathogen. However, implementation of key native pinewood management strategies, including encouraging regeneration in particular, are necessary in order to facilitate the adaptive evolution of native forests to increased levels of DNB. The effectiveness of this response will depend on the rapidity of adaptation of the pathogen. Measures to limit adaptation where possible, including the use of pathogen monitoring and control in nurseries and the limitation of pathogen movement into native pinewoods, should be continued.