A.V. Pires

Quantitative trait loci mapping for meat quality traits in swine chromosome 6

Realizou-se o mapeamento de QTL no cromossomo 6 suino (SSC6), associado as caracteristicas de qualidade da carne. Um total de 557 animais de uma populacao F2 foi obtido do cruzamento entre dois machos da raca nativa brasileira Piau e 18 femeas comerciais, cujos genotipos foram obtidos para 13 marcadores microssatelites. As caracteristicas avaliadas na F2 foram pH, medido 45 minutos e 24 horas post-mortem (pH45 e pH24, respectivamente); perda por gotejamento (DL); perda por cozimento (CL); perda total (TL); gordura intramuscular (IMF); maciez objetiva (OT); luminosidade (L); indice de vermelho (A); indice de amarelo (B); tonalidade de cor (h); e indice de saturacao (c). Utilizou-se o metodo de regressao por intervalo de mapeamento, por meio do programa QTL Express. Foram detectados QTLs significativos para pH45 e DL, sugestivos para DL, e nao foram encontrados QTLs para as demais caracteristicas. Constatou-se que grupos genicos, localizados em torno de 76, 88 e 97cM, podem atuar no pH45 e no DL. Nas regioes dos picos da estatistica F, onde se verificaram QTLs sugestivos para DL, devem ser incluidos mais marcadores, para confirmar a presenca de QTLs.

Estudo da divergência genética entre linhagens de matrizes de frangos de corte por meio de análise multivariada

Genetic divergence among broiler lines (L1, L2, L3 and L4) was studied by multivariate analysis. Four economic important traits were evaluated in three periods (initial, medium and total): age at first egg, egg number, average egg weight and body weight. The study of the genetic divergence among lines included the following techniques:Multivariate analysis of variance, cluster analysis using Mahalanobis generalized distance and Tocher optimization method, and canonical variables analysis. Significant difference was obtained by the larget Roy eigenvalue test. The cluster analysis of traits in the initial (L1 and L2; L3 and L4) and medium (L2 and L4; L1 and L3) periods grouped the four genotypes in three groups, and in total period the genotypes were grouped in two groups (L2, L3, L4 and L1). Canonical variables analysis showed that the first two canonical variables accounted for more than 96% of the total variation in the three periods. This allowed to represent the performance of genotypes in a bidimensional dispersion graph. In the total period of production study the genetic divergence was lower.

Estudo da divergência genética entre linhas de suínos utilizando técnicas de análise multivariada

Performance and genetic divergence among Duroc, Landrace and Large White breeds, using multivariate techniques were studied. Birth litter size, weaning litter size, birth litter weight, weaning litter weight, average weight gain from birth to weaning and mortality rate from birth to weaning were included in the study. Breed performance was evaluated by multivariate analysis of variance and discriminant linear function of Fisher, using tests of Roy greatest root and Roy union-intersection for multiple comparison. The study of genetic divergence was made by means of canonical variable analyses. Landrace and Large White breeds presented, in general, better performance than Duroc breed in the studied traits, and the three breeds had similar birth litter size. Landrace and Large White breeds were genetically similar but had higher genetic divergence related to Duroc breed.

Estudo da divergência genética entre seis linhas de aves Legorne utilizando técnicas de análise multivariada

Genetic divergence among six Leghorn lines (L1, L2, L3, L4, L5 e L6), developed by Universidade Federal de Vicosa, Brazil, was evaluated using canonical variate analysis and grouping method of Tocher. Eight traits were used: body weight at 40 weeks, at 48 weeks, at 56 weeks; egg weight at 40 weeks, at 44 weeks, at 52 weeks, at 60 weeks and laying ratio from 40 to 62 weeks of age. Significant differences were observed among lines for the studied traits. The line L4 was divergent in comparison with the other ones, showed the smallest canonical mean and was allocated in a different group. The performance of different genetic groups was also evaluated by multivariate analysis of variance, using Roy test of the largest eigenvalue and the Roy principle for multiple comparisons. Genetic divergence among UFVs lines was observed and body weight at 40 weeks was the trait that more contributed for this divergence.

Crescimento de codornas de diferentes grupos genéticos por meio de modelos não lineares

ABSTRACTThis work aimed to adjust nonlinear models to describe the growth pattern of meat type and posture quail genotypes from hatch to 35 days of age. A total of 1280 male and female quails from EV1, EV2, UFV1, UFV2, UFV3, LF1 and LF2 and Posture genotypes were weighed every seven days, from hatch to 35 days of age. Brody, Gompertz, Logistic, von Bertalanffy and Richards models were used to fit the growth of the genetic groups. Statistical analyses were performed using PROC NLIN of SAS (Statistical Analysis System, version 9.0). The criteria used to select the model showing the best goodness of fit to the growth of the genotypes were: Adjusted Coefficient of Determination (R2), Asymptotic Standard Deviation (DPA), Absolut Mean Deviation (DMA), Asymptotic Index (AI), Bayesian Information Criterion (BIC), Akaike Information Criterion (AIC) and Errors Mean Square (MSE). All nonlinear models converged for the studied genotypes, except Richard the model for the Posture genotype. In general, the estimated parameters for the growth curve using nonlinear models suggested higher precocity for the Posture genotype in comparison to meat type genotypes. The Richard model overestimates the inflection point for all genotypes, except for the Posture genotype. The Gompertz, Logistic and von Bertalanffy are recommended to describe the growth patterns of the studied quail genetic groups. The Brody model did not converge and is not recommended to describe the genetic growth of the studied groups.

Modelos lineares generalizados mistos na avaliação genética da prenhez precoce na raça Nelore

This study aimed to use the generalized linear models with probit and logit link function to evaluate early pregnancy, and to observe the effects on genetic variability and on sire selection when different ages are adopted in the definition of this trait. Early pregnancy was studied at 15 (EP15), and 21 (EP21) months. The analysis was done in R software. Pearson correlations (PC), between genetic predicted values and percentage of bulls in common considering only 10% of bulls with higher genetic values (TOP 10), between classification by logit and probit models and in each model among EP15 and EP21, were calculated. The heritability for EP15 and EP21 were close between models, except for EP15 using probit link function. PC and TOP10 among models were high. The Akaike and Bayesian criteria reported was similar between models. TOP10, considering the same model, among EP15-EP21 were moderated between EP15-EP21.

Seleção para a produção de ovos em períodos parciais e acumulados em linhagem de frango de corte comercial

The aim of this study was to estimate genetic parameters for partial and cumulative egg production in a commercial broiler female line. Ten monthly periods between 25 and 64 weeks, three partial periods of 25 to 32, 33 to 48 and 49 to 64 cumulative weeks and three periods of 25 to 30, 40 and 50 weeks of age and total egg production were considered. The restricted maximum likelihood method under the animal model was used to estimate the covariance components and genetic parameters. The fixed effect of incubation and the additive genetic and residual random effects were considered. The estimated heritability ranged from 0.12 to 0.41. These estimates showed that the anterior and posterior periods of the higher production have greater genetic variability. The genetic correlations between periods of the egg production studied ranged from -0.12 to 0.98. In general, the pattern of variation was similar between the strategies evaluated and all were genetically associated with the total egg production. The results of this study showed that the improvement of the total egg production is feasible by selection of partial records. However, considering the relative efficiency of selection, the second month and the periods from the fortieth week of production would be the most suitable.

Seleção e classificação multivariada de modelos não lineares para frangos de corte

Objetivou-se com este estudo utilizar a tecnica de analise de agrupamento para classificar modelos de regressao nao lineares usados para descrever a curva de crescimento de frangos de corte, levando em consideracao os resultados de diferentes avaliadores de qualidade de ajuste. Para tanto, utilizaram-se dados de peso corporal e idade dos seguintes grupos geneticos de frangos de corte: Cobb500, Hubbard Flex e Ross308, de ambos os sexos, constituindo, assim, seis classes. Foram ajustados 10 modelos nao lineares, cuja qualidade de ajuste foi medida pelo coeficiente de determinacao ajustado, pelos criterios de informacao de Akaike e bayesiano, pelo quadrado medio do erro e pelo indice assintotico. A analise de agrupamento indicou os modelos logistico, Michaelis-Menten, Michaelis-Menten modificado e von Bertalanffy como os mais adequados a descricao das curvas de crescimento das seis classes estudadas.

Divergência genética entre genótipos de frangos tipo caipira

ABSTRACTThe aim of this study was to evaluate the genetic divergence among seven genotypes of alternative strain of broiler chickens of the Redbro strain using the performance characteristics using multivariate analysis. We used 840 day old male chicks, distributed in a completely randomized design, with the following genotypes: Caboclo, Carijo, Colorpak, Gigante Negro, Pesadao Vermelho, Pescoco Pelado and Tricolor. After the consistency of the data, the following variables were analyzed: average daily gain, average daily feed intake and feed conversion for the periods: 1 to 28, 1 to 56, 1 to 70 and 1 to 84 days of age, body weight at birth, at 28, 56, 70 and at 84 days old. The performance of genotypes was assessed by multivariate analysis of variance and Fishers linear discriminant function, using the tests of the largest eigenvalue of Roy and the Roy union-intersection for multiple comparisons. The study of genetic diversity was done by canonical variate analysis and the method of Tocher. The genotypes Caboclo and Gigante Negro had different canonical averages from the other genotypes. The first two canonical variables accounted for 97.41% of the variation among genotypes. The genetic divergence between the genotypes allowed the formation of four groups with the following genotypes: group 1 - Colorpak, group 2 - Pesadao Vermelho and Pescoco Pelado; group 3 - Carijo and Tricolor, and group 4 - Caboclo and Gigante Negro.

Lisina digestível na ração de frangos de corte tipo caipira na fase de crescimento

This experiment was conducted to determine the requirements of digestible lysine in male and female free-range broiler chickens (Redbro lineage) during the growth phase. Six hundred and thirty broiler chickens were allocated in 30 pens with access to the pasture area. The experimental design was completely randomized in a 5x2 (lysine and gender) factorial arrangement with 3 repetitions with 21 chickens each. The levels of digestible lysine evaluated were: 7.07, 8.07, 9.07, 10.07 and 11.07g/kg. The performance traits evaluated were lysine intake, feed intake, weight gain and feed conversion ratio. An interaction effect (P<0.05) was observed between dietary lysine level and gender for body weight gain. There was an effect (P<0.01) of the levels of lysine on lysine intake, body weight gain and feed conversion ratio. It was found that all the variables were affected (P<0.05) for the gender of chickens. We recommended 10.08 and 9.49 g of digestible lysine/kg diet, corresponding to the estimated intake of 21 and 20g of lysine, for males and females, respectively, for better body weight gain of chickens. For better feed conversion ratio, the recommendation is of 9.61 g of lysine/kg of diets, for chickens of both genders, corresponding to the estimated intake of 20g of lysine.