Interação genótipo x ambiente para ganho de peso pós-desmama de bovinos de corte compostos.

Foram estimados parâmetros genéticos para a característica ganho de peso pós-desmama (GP), com o objetivo de verificar a presença de interação genótipo x ambiente (GxE). Os ambientes foram definidos com base em variáveis climáticas e geográficas das fazendas por meio de técnicas de análise multivariada. Foram formados 6 grupos geoclimáticos de fazendas, sendo então o GP em um grupo, considerado como característica diferente em relação a outro grupo. As estimativas de herdabilidade variaram de 0,04 a 0,20, evidenciando heterogeneidade de variâncias. As correlações genéticas entre os grupos geoclimáticos variaram de 0,31 a 0,93, sendo a GxE mais pronunciada entre os grupos 1 e 3, 1 e 4. Estes grupos estavam justamente localizados nas regiões mais distintas entre si com relação às variáveis geoclimáticas. Foi constatada GxE entre a maioria dos grupos geoclimáticos de fazendas, evidenciando que a avaliação genética dos animais, neste caso, deveria ser feita regionalmente ou a GxE ser incluída no modelo estatístico

Phenotypic plasticity of composite beef cattle performance using reaction norms model with unknown covariate.

The objective of the present study was to determine the presence of genotype by environment interaction (G × E) and to characterize the phenotypic plasticity of birth weight (BW), weaning weight (WW), postweaning weight gain (PWG) and yearling scrotal circumference (SC) in composite beef cattle using the reaction norms model with unknown covariate. The animals were born between 1995 and 2008 on 33 farms located throughout all Brazilian biomes between latitude −7° and −31°, longitude −40° and −63°. The contemporary group was chosen as the environmental descriptor, that is, the environmental covariate of the reaction norms. In general, higher estimates of direct heritability were observed in extreme favorable environments. The mean of direct heritability across the environmental gradient ranged from 0.05 to 0.51, 0.09 to 0.43, 0.01 to 0.43 and from 0.12 to 0.26 for BW, WW, PWG and SC, respectively. The variation in direct heritability observed indicates a different response to selection according to the environment in which the animals of the population are evaluated. The correlation between the level and slope of the reaction norm for BW and PWG was high, indicating that animals with higher average breeding values responded better to improvement in environmental conditions, a fact characterizing a scale of G × E. Low correlation between the intercept and slope was obtained for WW and SC, implying re-ranking of animals in different environments. Genetic variation exists in the sensitivity of animals to the environment, a fact that permits the selection of more plastic or robust genotypes in the population studied. Thus, the G × E is an important factor that should be considered in the genetic evaluation of the present population of composite beef cattle.Firstview article 27 set. 2012

Synchronization in Von Bertalanffy’s models

Many data have been useful to describe the growth of marine mammals, invertebrates and reptiles, seabirds, sea turtles and fishes, using the logistic, the Gom-pertz and von Bertalanffy's growth models. A generalized family of von Bertalanffy's maps, which is proportional to the right hand side of von Bertalanffy's growth equation, is studied and its dynamical approach is proposed. The system complexity is measured using Lyapunov exponents, which depend on two biological parameters: von Bertalanffy's growth rate constant and the asymptotic weight. Applications of synchronization in real world is of current interest. The behavior of birds ocks, schools of fish and other animals is an important phenomenon characterized by synchronized motion of individuals. In this work, we consider networks having in each node a von Bertalanffy's model and we study the synchronization interval of these networks, as a function of those two biological parameters. Numerical simulation are also presented to support our approaches

Efeito médio de substituição alélica para os polimorfismos CAPN4753 e UOGCAST no gene da calpaína e calpastatina.

Os objetivos deste trabalho foram avaliar possíveis interações alélicas para os polimorfismos nos genes da µ-calpaína (CAPN4753) e da calpastatina (UOGCAST1), ligados a característica de maciez da carne. Nesse trabalho, foram utilizados 590 animais da raça Nelore. Após a extração do DNA de amostras de sangue por precipitação em NaCl. A identificação e determinação dos polimorfismos para os marcadores foram realizadas pelo sistema de detecção TaqManTM utilizando-se PCR em Tempo Real. A análise de maciez da carne, aos 7, 14 e 21 dias de maturação, foi realizada com amostras de carne do Longissimus dorsi, retiradas entre a 12ª e 13ª costela e cisalhadas utilizando-se um Warner Bratzler Shear Force. Foram observados resultados significativos para o efeito médio de substituição aos 14 dias de maturação da carne, apenas para o polimorfismo no gene da calpastatina, e aos 21 dias para ambos os polimorfismos (CAPN4753 e UOGCAST1)

Genotypic and allelic frequencies of gene polymorphisms associated with meat tenderness in Nellore beef cattle.

The objectives of this study were to characterize the allelic and genotypic frequencies of polymorphisms in the μ-calpain and calpastatin genes, and to assess their association with meat tenderness and animal growth in Nellore cattle. We evaluated 605 Nellore animals at 24 months of age, on average, at slaughter. The polymorphisms were determined for the molecular markers CAPN316, CAPN530, CAPN4751, CAPN4753, and UOGACAST1. Analyses of meat tenderness at 7, 14, and 21 days of maturation were performed in samples of longissimus thoracis obtained between the 12th and 13th rib and sheared using a Warner Bratzler Shear Force. Significant effects were observed for meat tenderness at days 7, 14, and 21 of maturation for the marker CAPN4751, at day 21 for the marker CAPN4753, and at days 14 and 21 for the marker UOGCAST1. For genotypic combinations of markers, the results were significant for the combination CAPN4751/UOGCAST1 in the three maturation periods and CAPN4753/UOGCAST1 at days 14 and 21 of maturation

Associação de polimorfismos no gene da u-calpaína com a maciez da carne em animais da raça Nelore.

Os bovinos de origem Bos indicus são preferidos nos trópicos devido a sua maior resistência as adversidades ambientais. No entanto, estes animais não produzem carne tão macia quanto os taurinos. A seleção assistida por marcadores relacionados à maciez da carne, como é o caso da protease calpaína, pode auxiliar na melhoria da característica. Nesse trabalho, foram utilizados 229 animais da raça Nelore. Após a extração do DNA de amostras de sangue, por desproteinização em presença de NaCl a identificação e determinação dos polimorfismos para três marcadores (CAPN316, CAPN530 e CAPN4751) foi realizada pelo sistema de detecção TaqManTM utilizando-se PCR em Tempo Real. A análise de maciez da carne, aos 7, 14 e 21 dias de maturação, foi realizada com amostras de carne do Longissimus dorsi, retiradas entre a 12a e 13ª costela e cisalhadas utilizando-se um Warner Braztler Shear Force. Os polimorfismos dos marcadores CAPN316 e CAPN530 não apresentaram efeitos significativos (P>0,05) para a maciez da carne aos 7, 14 e 21 dias de maturação. Foram verificados efeitos significativos para os polimorfismos do CAPN4751 em relação à maciez da carne aos 7 (P=0.001), 14 (P=0.005) e 21 (P=0.006) dias de maturação

Association of single nucleotide polymorphisms in the bovine leptin and leptin receptor genes with growth and ultrasound carcass traits in Nellore cattle

Given the important role of leptin in metabolism, we looked for a possible association of leptin and leptin receptor polymorphisms with carcass and growth traits in Nellore cattle. We examined associations of leptin and leptin receptor SNPs with ultrasound carcass (longissimus dorsi muscle area (ribeye area), backfat thickness and rump fat thickness and growth traits (weaning weight adjusted to 210 days of age, yearling weight adjusted to 550 days of age, weight gain of weaning to yearling and scrotal circumference adjusted to 550 days of age) of 2162 Bos primigenius indicus (Nellore) animals. Allele and genotypic frequencies were calculated for each marker. Allele substitution, additive and dominance effects of the polymorphisms were also evaluated. Some alleles of the molecular markers had low frequencies, lower than 1%, in the sample analyzed, although the same polymorphisms described for B. p. taurus cattle were found. Due to very low allelic frequencies, the E2JW, A59V and UASMS2 markers were not included in the analysis, because they were almost fixed. E2FB was found to be significantly associated with weight gain, ribeye area and backfat thickness. The promoter region markers, C963T and UASMS1, were also found to be significantly associated with ribeye area. T945M was significantly associated with weight gain. We conclude that the leptin and receptor gene markers would be useful for marker-assisted selection.FUNPEC/RPFUNPEC/R