Paulo Luiz Souza Carneiro

Melhoramento e estrutura populacional em bubalinos da raça Mediterrâneo no Brasil

O objetivo deste trabalho foi avaliar a estrutura populacional e os progressos geneticos, fenotipicos e ambientais de caracteristicas de desenvolvimento ponderal, em bubalinos da raca Mediterrâneo. Foram utilizadas informacoes dos pesos ajustados aos 205, 365 e 550 dias de idade, de 6.243 bubalinos nascidos no periodo de 1974 a 2003, provenientes de quatro fazendas. As estimativas dos coeficientes de herdabilidade foram altas para os pesos ajustados nas tres idades. Os rebanhos apresentaram ganho genetico positivo quanto a essas tres caracteristicas, porem, aquem do possivel, provavelmente em razao da selecao baseada somente no fenotipo, realizada pelos produtores. Para aumento nos ganhos geneticos, sao necessarios a reducao do intervalo de geracao, o aumento do tamanho efetivo, o uso de reprodutores avaliados com base nos valores geneticos preditos pelo BLUP e o controle dos acasalamentos de animais aparentados.

Desenvolvimento ponderal e diversidade fenotípica entre cruzamentos de ovinos Dorper com raças locais

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 animals development. The estimates of growth curve based on parameters from the Logistic model indicated that the genetic group Dorper x Santa Ines 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 Ines.

Parâmetros e tendências da produção de leite em bubalinos da raça Murrah no Brasil

Objetivou-se estimar os parâmetros e avaliar as tendencias genetica e fenotipica para a producao de leite ajustada aos 305 dias em bubalinos da raca Murrah nascidos no periodo de 1982 a 2003. Os parâmetros e os valores geneticos foram estimados por meio do aplicativo MTDFREML. A tendencia genetica foi estimada pela regressao dos valores geneticos sobre o ano de nascimento, por duas metodologias: 1) regressao linear; 2) regressao por meio de polinomios articulados utilizando-se a funcao de alisamento spline. A herdabilidade e a repetibilidade estimadas foram de 0,20 e 0,36, respectivamente. As tendencias (regressao linear) fenotipica e genetica foram significativas e iguais a 32,86 e 0,85 kg/ano, respectivamente. O ganho genetico foi positivo, constatando-se instabilidade na tendencia genetica no decorrer dos anos, com periodos de ganhos e outros de perdas geneticas. A maior parte do ganho observado em alguns periodos resultou de melhorias nas condicoes ambientais.

Caracterização fenotípica e genética da produção de leite e do intervalo entre partos em bubalinos da raça Murrah

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.

The Indubrasil breed in the Brazilian Northeast: breeding and population structure

In order to provide knowledge for breeding, conservation programs and expansion policies of the Indubrasil breed from northeastern Brazil, the evolutionary history, estimates of genetic parameters and the populational structure of the breed were studied. Pedigree information was used from animals born from 1964 to 2006 and the adjusted weights at 205, 365 and 550 days of age of bovines born from 1976 onwards. The heritability coefficient estimates were lower than those reported in the literature for the adjusted weights at the three ages (P205: direct 0.11 ± 0,03 and maternal 0.01 ± 0.03; P365: direct 0.16 ± 0.04 and P550: direct 0.15 ± 0.05) and the genetic gains for the evaluated traits decreased in the sampled period (P205: -0.028 kg/year; P365: -0.030 kg/year and P550: -0.025 kg/year). The low genetic variability and the reduced genetic gains were probably due to a reduction in the effective size and increasing inbreeding within the period. Furthermore, the drastic reduction in the number of births per year and the low use of unrelated sires within the herds make the Indubrasil breed a genetic group potentially threatened by extinction, so that conservationist and expansion programmes should be set up.

Cytogenetic and morphological diversity in populations of Astyanax fasciatus (Teleostei, Characidae) from Brazilian northeastern river basins

In the present work, morphometric and cytogenetic analyses were carried out in populations of the fish Astyanax fasciatus (Characidae) from Contas and Reconcavo Sul River basins (State of Bahia, Brazil), providing new data on the genetic structure of this species along the region. Based on morphologic measurements, we observed that populations from the same hydrographic basin were more similar to each other (Contas and Preto do Costa Rivers), and remarkably divergent from Reconcavo Sul (Mineiro Stream), as indicated by clustering analysis. Cytogenetic data revealed a same diploid number for all populations (2n = 48), but distinct karyotype formulae (8M+24SM+12ST+4A, FN = 92 in Contas River, 8M+24SM+10ST+6A, FN = 90 in Preto do Costa River, and 8M+18SM+16ST+6A, FN = 90 in Mineiro Stream). Ag-NORs were identified at telomeres on a subtelocentric chromosome pair, although multiple ribosomal sites have been detected in some specimens from Contas River. These results show that A. fasciatus populations from northeastern river basins are well differentiated and present peculiar cytogenetic features when compared to populations from other regions. Therefore, the apparent chromosomal plasticity of this species, likely to represent a complex of cryptic forms, is corroborated. Finally, we demonstrated that morphological features can be successfully used to support other sources of genetic information.

A multi-approach analysis of the genetic diversity in populations of Astyanax aff. bimaculatus Linnaeus, 1758 (Teleostei: Characidae) from Northeastern Brazil

Poucos estudos ictiofaunisticos estao disponiveis em rios tipicos do semi-arido, apesar da constante ameaca a diversidade local devido a influencias antropicas, com destaque para o represamento e construcao de barragens. O presente trabalho teve como objetivo avaliar, por meio de diferentes metodologias, a estrutura genetica de populacoes de uma especie de caracideo, Astyanax aff. bimaculatus, amplamente distribuida em bacias hidrograficas da Bahia, Nordeste do Brasil. Analises morfologicas (dados meristicos e morfometricos), citogeneticas (cariotipo e Ag-RONs) e moleculares (RAPD e SPAR) foram realizadas em especimes coletados a montante e a jusante da Barragem da Pedra, na calha principal do medio rio de Contas (bacia do Rio de Contas) e no ribeirao Mineiro, pertencente a bacia adjacente do Reconcavo Sul. Poucas diferencas externas foram detectadas entre as populacoes, sendo os individuos originarios do reservatorio, a montante da barragem, ligeiramente maiores. Os dados citogeneticos tambem mostraram padroes cariotipicos semelhantes (2n=50; 6m+28sm+12st+4a; FN= 96) e RONs situadas nos bracos curtos de ate dois pares cromossomicos, com variacao numerica inter- e intra-populacional. Contudo, as analises por RAPD e SPAR diferenciaram as tres populacoes de forma eficiente, revelando frequencias alelicas significativamente diferentes entre as localidades amostradas e indices significativos de estruturacao populacional (Fst=0.1868, P<0.0001). As diferencas entre populacoes do mesmo rio foram tao significativas quanto entre bacias hidrograficas distintas, indicando que a represa constitui uma barreira eficiente ao fluxo genico. Alem disso, acredita-se que peculiaridades ambientais de cada localidade possam tambem influenciar os padroes geneticos encontrados. Por outro lado, a similaridade entre amostras das bacias do Rio de Contas e Reconcavo Sul pode estar relacionada a uma historia evolutiva comum, ja que ambas estao geograficamente proximas. Por fim, o presente estudo demonstra que a realizacao de estudos envolvendo diferentes marcadores e extremamente util para a identificacao de estruturas de populacoes em especies amplamente distribuidas e para avaliacao dos impactos das atividades humanas sobre as populacoes naturais de peixes.

Bovine babesiosis and anaplasmosis complex: diagnosis and evaluation of the risk factors from Bahia, Brazil

Direct diagnoses were made by using - blood smears and nested PCR (nPCR) tests on 309 blood samples from crossbred dairy cattle in the municipality of Ibicaraí, Bahia. From diagnostic blood smear slides, the observed parasitic frequencies were 31.1% for Anaplasma marginale and 20.4% for Babesia sp. From nPCR diagnoses, they were 63% for A. marginale, 34% for Babesia bigemina and 20.4% for Babesia bovis. There were significant differences (P <0.01) between the two diagnostic methods (nPCR and blood smear slides). The compliance obtained from the kappa test was 0.41 and 0.48 for A. marginale and Babesia sp., respectively. The tick samples from the six farms analyzed using nPCR were only positive for A. marginale. Evaluation of the risk factors relating to the presence of ticks and the age of the animals showed that there was a significant association (P <0.01) with the frequency of animals infected with both pathogens. Therefore, under the conditions studied, nPCR proved to be a good tool for diagnosing the agents of the bovine babesiosis and anaplasmosis complex because of its sensitivity and specificity in comparison with blood smears. The municipality of Ibicaraí is an area with endemic prevalence of bovine babesiosis and anaplasmosis confirmed by nPCR and A. marginale is the main agent of the disease.

Population structure of Brazilian Gyr dairy cattle

The objective of the present study was to evaluate the genetic structure of Gyr cattle selected for milk production. Files of pedigree and production were composed of 27,610 animals. The ENDOG program was used for the calculation of individual inbreeding coefficient (F) and coefficient of average relatedness (AR), effective number of animals(Ne), effective number of founders (fe) and ancestors (fa), and generation interval (GI). Individual inbreeding coefficients and average relatedness in the population were 2.82% and 2.10%, respectively. It was observed a reduction in the effective number of animals, especially after publication of the results of the first progeny test. The estimated effective number of founders was 146 and 75 for the ancestrals. Out of those, only 28 ancestors accounted for the origin of 50% of the population genes. The average generation interval was 8.41 years and it was longer for males than for females. For maintaining genetic variability in future generations, it should be invested mating strategies that reduce inbreeding and which do not use massively only some high breeding value sires.

Genetic parameters for milk yield, lactation length and calving intervals of murrah buffaloes from brazil

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.