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Resumo -O objetivo deste trabalho foi avaliar a estrutura populacional e o progresso genético e fenotípico de características de desenvolvimento ponderal, em bovinos da raça Nelore, no Estado da Bahia. Foram utilizadas informações de pedigree de animais nascidos no período de 1955 a 2007, e dados dos pesos ajustados aos 205, 365 e 550 dias de idade, de bovinos nascidos de 1970 a 2006. As estimavas dos coefi cientes de herdabilidade foram de moderadas a altas, quanto aos pesos ajustados nas três idades. Os rebanhos apresentaram ganho genético positivo nas três características, porém, de baixa magnitude. A mudança fenotípica no decorrer dos anos foi quase exclusivamente relacionada à melhoria ambiental. O tamanho efetivo da população de Nelore do Estado da Bahia tem sido alto em alguns períodos, o que tem levado a menor incremento de endogamia e maiores ganhos genéticos. O intervalo de geração é alto e sua redução é importante para que se possa alcançar maior ganho genético anual.Termos para indexação: endogamia, intervalo de geração, ganho genético, pedigree, seleção, tamanho efetivo. Genetic progress and population structure in Nellore cattle in Bahia State, BrazilAbstract -The objective of this work was to evaluate the population structure as well as the genetic and phenotypic progress in growth development traits of Nellore cattle raised in Bahia state, Brazil. Pedigree data of bovines, born between 1955 and 2007, and weight values adjusted to 205, 365, and 550 days of age, from 1970 to 2006, were used. The heritability coeffi cients were moderate to high for the adjusted weights, in all three ages. The herds presented a positive but small genetic gain. The phenotypic changes over years were almost exclusively related to environmental improvements. The effective size of the Nellore population raised in Bahia state has increased over some periods, thereby decreasing the inbreeding rate and leading to higher genetic gains. The generation interval is high and its reduction is important, in order to increase the annual genetic gain.

Resumo -O objetivo deste trabalho foi estimar as correlações, herdabilidades, repetibilidades, tendências gené-ticas e fenotípicas, e avaliar as distribuições univariada e bivariada da produção de leite e do intervalo entre partos, em fêmeas bubalinas da raça Murrah, paridas no período de 1982 a 2003. As tendências genéticas e fenotípicas foram estimadas pelas regressões das variáveis dependentes sobre o ano de parto, pelos métodos: regressão linear e regressão não paramétrica, utilizando-se a função de alisamento Spline. As herdabilidades estimadas foram 0,21 e 0,02, e as repetibilidades, 0,32 e 0,06, para a produção de leite e intervalo entre partos, respectivamente. As correlações genética, fenotípica e ambiental foram -0,22, 0,01 e 0,03, respectivamente. As tendências genéticas (regressão linear) foram significativas e iguais a 1,57 kg por ano e 0,085 dia por ano, e as tendências fenotípicas foram 27,74 kg por ano e 0,647 dia por ano, para a produção de leite e intervalo entre partos, respectivamente, tendo sido significativa apenas para a produção de leite. A correlação negativa sugere a existência de antagonismo favorável entre produção de leite e intervalo entre partos; assim é possível selecionar animais com altos valores genéticos para a produção de leite e com menores valores para o intervalo entre partos.Termos para indexação: análise bivariada, correlações, herdabilidade, tendência genética. Phenotypic and genetic characterization of the milk yield and calving interval in buffalo of the Murrah breedAbstract -The objective of this work was to estimate the correlations, heritabilities, repeatabilities, phenotypic and genetic trends, and to evaluate the univariate and bivariate distributions of the milk yield and calving interval of Murrah breed buffalo, calved from 1982 to 2003. The genetic and phenotypic trends were estimated by regressions of the dependant variables on year of the animals calving, based on two methods: linear regression and articulated polynomial regression. The heritabilities estimates were 0.21 and 0.02, and the repeatabilities 0.32 and 0.06, for milk yield and calving interval, respectively. The genetic, phenotypic and environmental correlations were -0.22, 0.01 and 0.03, respectively. Genetics trends (linear regression) were significant and equal to 1.57 kg per year and 0.085 day per year, and the phenotypics trends were 27.74 kg per year and 0.647 day per year, for milk yield and calving interval, respectively, being significant just for milk yield. The negative genetic correlation suggests that there is a favorable relationship between milk yield and calving intervals, thus it is possible to select animals of high breeding values for milk yield and with low breeding values for calving intervals.

Resumo -O objetivo deste trabalho foi comparar o desenvolvimento ponderal, por meio de curva de crescimento e pesos ajustados e avaliar a diversidade entre ovinos cruzados Dorper com as raças locais, com base em características de carcaça e morfológicas. Growth rate and phenotypic diversity among crosses of Dorper ovines and local breedsAbstract -The goal of this work was to compare growth rate, by mean of growth and adjusted weight curves, and to analyze the diversity among crosses of Dorper ovines and local breeds, based on morphological and carcass features. Crossed animals were weighed in a 15-day-interval and the effects of sex, year and genetic group were analyzed. The non-linear Logistic model was used to estimate curve parameters and the degree of similarity among genetic groups was evaluated through canonic variables. Sex did not influence significantly on weight. There was a significant effect related to year and genetic group over animal's development. The estimates of growth curve based on parameters from the Logistic model indicated that the genetic group Dorper x Santa Inês presented a faster growth rate, as estimated by weight at maturity and maturity rate, followed by the genetic groups Dorper x Morada Nova and Dorper x Rabo Largo. Clustering analysis reinforced the differences among genetic groups, placing the three crosses in two groups, one comprising Dorper x Morada Nova and Dorper x Rabo Largo, and another including the cross Dorper x Santa Inês.

Análise de agrupamento na seleção de modelos de regressão não-lineares para curvas de crescimento de ovinos cruzadosCluster analysis applied to nonlinear regression models selection to growth curves of crossed lambs

Drip‐tips are a common feature of the leaves of rain forest trees, but their functional significance remains contested. The most widely accepted hypothesis is that drip‐tips assist drainage of the lamina thereby aiding drying of the leaf surface and reducing the rate of colonization and abundance of epiphyllic organisms. The drying action of drip‐tips may also enhance transpiration and reduce the need for investment in support structures. Furthermore, drip‐tips may help prevent splash erosion around the base of the tree. Data from 130 forest Amazonian plots are used to investigate the abundance and distribution of drip‐tips and, through regression methods that incorporate spatial autocorrelation, seek to identify associations between the frequency of drip‐tips and a range of climatic variables. The average frequency of species and trees with drip‐tips across all plots was 32 and 33 percent, respectively. Trees and species with drip‐tips were significantly more prevalent in the Central‐East Amazon than the other regions. Drip‐tips were also associated with tree species that have smaller maximum heights and with trees with smaller trunk diameters. The proportion of species and individuals with drip‐tips was more strongly correlated with precipitation of the wettest trimester than with total annual precipitation or length of the dry season. Our results extend and provide support for both existing hypotheses for the functional benefit of possessing a drip‐tip. Moreover, the currently unrecognized macrogeographic association between the frequency of drip‐tips in trees of the tropical forest understory and areas of heavy precipitation suggests a new function for this trait.

Resumo -O objetivo deste trabalho foi avaliar a sensibilidade ao ambiente em bovinos da raça Nelore por meio de diferentes modelos de normas de reação e estimar o progresso genético no gradiente ambiental. Determinaram-se os parâmetros ganho de peso da desmama ao sobreano (GP345) e o peso ajustado aos 205 dias de idade (P205). Um modelo animal padrão (MA), dois modelos hierárquicos de normas de reação com homocedasticidade de variância residual e dois com heterogeneidade foram utilizados. O modelo hierárquico de normas de reação homocedástico com um passo apresentou o melhor ajuste. Os coeficientes de herdabilidade diretos do ambiente baixo para o ambiente alto, no gradiente ambiental, foram de 0,03 a 0,63 e de 0,13 a 0,62, respectivamente, para GP345 e P205. As correlações entre o intercepto e a inclinação da norma de reação foram de: 0,93, para GP345 (direto); 0,95, para GP345 (materno); 0,92, para P205 (direto); e 0,82, para P205 (materno). As correlações indicam que animais com alto valor genético tendem a responder positivamente aos melhores ambientes. As tendências genéticas mostraram ganhos para os efeitos diretos, principalmente nos melhores ambientes. Há variação genética quanto à sensibilidade dos animais, nos diferentes ambientes, fato que permite a seleção de animais com genótipos mais adequados para a produção em determinado ambiente.Termos para indexação: avaliação genética, correlação genética, parâmetros genéticos, plasticidade fenotípica, reprodutores, sensibilidade ambiental. Genotype x environment interaction via models of reaction norms for growth traits in Nelore cattleAbstract -The objective of this work was to evaluate the sensitivity of Nelore cattle to the environment by different models of reaction norms and to estimate the genetic progress in environmental gradient. The parameters weight gain from weaning to yearling (WG345) and adjusted weight at 205 days of age (W205) were determined. A standard animal model (AM), two reaction norm hierarchical models with residual variance homoscedasticity, and two with heterogeneity were used. The homoscedastic reaction norm hierarchical model with one step showed the best fit. The direct heritability coefficients from the low environment to the high one, in environmental gradient, were 0.03 to 0.63 and 0.13 to 0.62, respectively, for WG345 and W205. The correlations between the intercept and the slope of the reaction norm were: 0.93, for WG345 (direct); 0.95, for WG345 (maternal); 0.92, for W205 (direct); and 0.82, for W205 (maternal). The correlations indicate that animals with high genetic value tend to positively respond to better environments. The genetic trends showed gains for the direct effects, mainly in the best environments. There is genetic variation for sensitivity of animals, in different environments, a fact that allows of the selection of animals of more appropriate genotypes for the production in a particular environment.

-The major objective of this study was to estimate heritability and genetic correlations between milk yield (MY) and calving interval (CI) and lactation length (LL) in Murrah buffaloes using Bayesian inference. The database used belongs to the genetic improvement program of four buffalo herds from Brazil. To obtain the estimates of variance and covariance, bivariate analyses were performed with the Gibbs sampler, using the program MTGSAM. The heritability coefficient estimates were 0.28, 0.03 and 0.15 for MY, CI and LL, respectively. The genetic correlations between MY and LL was moderate (0.48). However, the genetic correlation between MY and CI showed large HPD regions (highest posterior density interval). Milk yield was the only trait with clear potential for genetic improvement by direct mass selection. The genetic correlation between MY and LL indicates that indirect selection using milk yield is a potentially beneficial strategy. The interpretation of the estimated genetic correlation between MY and CI is difficult and could be spurious.