Eufrázio de Souza Santos

Estimativas de parâmetros de curvas de crescimento de bovinos Zebu, criados no estado de Pernambuco

Foram analisados dados de pesagem constantes no banco de dados de Controle de Desenvolvimento Ponderal da Associacao Brasileira de Criadores de Zebu (ABCZ), referentes a 24.028 animais Zebu das racas Guzera, Nelore e Nelore Mocho, nascidos entre 1960 e 2000, objetivando-se estimar parâmetros de curvas de crescimento por meio de equacoes nao-lineares e verificar a influencia de efeitos fixos e aleatorios sobre as estimativas. As pesagens ocorreram ao nascimento e em intervalos de 90 dias ate dois anos de idade. Para analise dos dados de peso-idade, foram utilizados os seguintes modelos nao-lineares: Brody, Gompertz, Logistico, Mitscherlich, von Bertalanffy, Richards e Logistico duplo. As fontes de variacao estudadas no modelo misto foram sexo, propriedade, ano e mes de nascimento, tipo de sistema de criacao e interacao sexo*sistema de criacao, como efeitos fixos, e reprodutor e mae, como efeitos aleatorios. A equacao Logistica Dupla foi a que apresentou o melhor ajustamento e a Mitscherlich, o pior, segundo o numero de convergencias e o indice de ajuste. Os efeitos fixos mais influentes foram sexo, propriedade, ano e mes de nascimento e sistema de criacao. O efeito aleatorio mais influente foi o de mae. A variabilidade encontrada pode possibilitar a exploracao da modificacao da curva de crescimento por meio de programas de melhoramento genetico.

Tamanho da leitegada e pesos médios, ao nascer e aos 21 dias de idade, de leitões da raça Large White

The effects of season of birth (PE) and age of sow at birth (IMP) on litter size (TL); season of birth, age of sow and litter size on average weight at birth (PMN); season of birth age of sow, number of alive piglets at birth (NV), and percentage of alive males on average weight at 21 days of age (PM21) of 3259 Large White piglets born from June/85 to June/96 were evaluated by multiple regression analyses. The IMP effect on TL was significant. The average TL was 9.73±2.78. Larger litters were observed for sows from 2.84 to 3.83 years of age. The average PMN and PM21 were 1.35kg±0.18 e 5.06kg±1.00, respectively. The IMP and TL effects on PMN traits were linear and significant. A decrease of 20g on piglet weight was estimated for each additional piglet in the litter. The effect of NV was significant only for PM21 trait.

Comparação de métodos de prognose da estrutura diamétrica de uma floresta estacional semidecidual secundária

Objetivou-se comparar prognoses da distribuicao diametrica de uma floresta estacional semidecidual secundaria obtidas pelos metodos da razao de movimentacao, de Wahlenberg e da matriz de transicao. Foram utilizados dados obtidos em dez anos de monitoramento do ensaio de producao sustentavel em floresta secundaria, implantado em 1986 pela companhia Vale do Rio Doce, em Rio Vermelho e Serra Azul de Minas, Minas Gerais. Foram considerados apenas os dados referentes a area sem intervencao, e as arvores foram agrupadas por classe de diâmetro de 5 cm. As analises da taxa de crescimento foram realizadas a partir dos periodos de monitoramento de 1986 a 1996, com intervalos de dois em dois anos. As prognoses da estrutura diametrica para 1994 e 1996 foram realizadas por meio dos metodos da razao de movimentacao, de Wahlenberg e da matriz de transicao e comparadas com a estrutura real. A consistencia da prognose obtida por cada metodo foi realizada por meio do teste de Kolmogorov-Smirnov (P = 0,05). Quanto ao numero medio de arvores, as prognoses obtidas pelos tres metodos foram similares a estrutura real, tanto para 1994 como para 1996. No entanto, quanto a distribuicao diametrica, os metodos nao foram eficientes quando comparados com a estrutura real. Pode-se concluir que os metodos da razao de movimentacao, de Wahlenberg e da matriz de transicao foram eficientes na prognose do numero medio de arvores/ha da floresta estudada, porem nao o foram na prognose da distribuicao diametrica da mesma floresta.

Estabilidade em análise de agrupamento: estudo de caso em ciência florestal

The main objective of this research was to propose a system to the study and interpretation of stability in cluster analysis through several cluster algorithms in vegetation data. The data set used derived from a survey in the Silviculture Forest at Federal University of Vicosa - MG. To perform the cluster analysis, the Mahalanobis distance matrices were estimated on basis of original data and bootstrap resampling. Also, the single linkage, complete linkage, average distances, centroid, median and Ward methods were used. Chi-square test was applied to detect the association among the methods. A co-phenetic correlation was obtained for the cluster methods. The results for the method associations were very similar, indicating that any algorithm of the studied clusters is stabilized, and in fact, that groups exist among the analyzed individuals. However, it was verified that the methods are coincident, except for the centroid and Ward, and also the centroid and median methods, when compared to Ward, respectively, based on the Mahalanobis matrices derived from the original data set and bootstrap. The methodology proposed is promising to the study and interpretation of the stability of cluster analysis methods in vegetation data.

Uso de funções de covariância na descrição do crescimento de bovinos Nelore criados no estado de Pernambuco

Random regression models using Legendre polynomials were used to describe the growth curve of Nelore cattle weighted every three months from birth to 720 days of age, in Pernambuco state, northeastern Brazil. Six different random regression models using Legendre polynomials of three, four, and five degrees to model additive genetic and permanent environmental effects, under homogeneous and heterogeneous residual variances with three classes were evaluated. According to the Akaikes information criteria, the five degree Legendre polynomial with homogeneous error was the best fitting model. Genetic and phenotypic correlations were low between weights at early and late stages of the weighting period, and high and approximately constant between weights at late stages. Genetic covariance of weights increased with age. Heritability estimates were low to moderate up to 60 days of age and reached values between 0.50 and 0.60 at older ages.

Herdabilidades de parâmetros de curvas de crescimento não-lineares em zebuínos, no estado de Pernambuco

Objetivou-se estimar parâmetros geneticos e fenotipicos de curvas de crescimento de modelos nao-lineares. Foram analisados dados de pesagem constantes no banco de dados de Controle de Desenvolvimento Ponderal da Associacao Brasileira de Criadores de Zebu (ABCZ), referentes a 24.028 animais Zebu, nascidos entre 1960 e 2000, das racas Guzera, Nelore e Nelore Mocho. As pesagens ocorreram ao nascimento e em intervalos de 90 dias ate dois anos de idade. Os seguintes modelos nao-lineares foram utilizados na analise dos dados de peso-idade: Brody, Gompertz, Logistico, von Bertalanffy e Richards. Os efeitos fixos estudados no modelo misto foram sexo, rebanho, ano e mes de nascimento e regime de criacao. As herdabilidades para os parâmetros foram de baixa a alta magnitude, em geral, para todos os modelos. As correlacoes geneticas entre peso assintotico e taxa de maturidade e entre peso assintotico e velocidade de crescimento foram negativas, enquanto aquelas entre taxa de maturidade e velocidade de crescimento foram positivas. As correlacoes fenotipicas foram negativas entre peso assintotico e taxa de crescimento e entre peso assintotico e velocidade de crescimento e positivas entre taxa e velocidade de crescimento. Encontrou-se variabilidade possivel de ser explorada em um programa de melhoramento genetico, especialmente para a raca Nelore, que apresentou amostra de dados e resultados mais consistentes.

Logistic model for determining factors associated with HIV infection among blood donor candidates at the Fundação HEMOPE

Objective To determine factors associated with HIV infection in blood donor candidates in Recife, Brazil. Methods A transversal study was performed of 106,203 blood donor candidates found eligible by the routine clinical screening process in the blood bank in Recife of the Fundação de Hematologia e Hemoterapia de Pernambuco (HEMOPE) in the period from January 1998 to November 2003. Additional indirect immune and western blot confirmation tests for HIV infection were performed and the candidates were classified as HIV positive or negative. The Chi-squared test and stepwise multiple logistic regression were conducted to examine any association between HIV infection and age, gender, place of residence, schooling, number of donations and serological tests for core hepatitis B antigen virus (anti-HBc), the hepatitis C antivirus (anti-HCV), human T-type antivirus lymph cells (anti-HTLV 1 and 2), serological tests for syphilis (VDRL) and the hepatitis B virus surface antigen (HBsAg). Results In the observed sample, 0.204% of blood donor candidates were found to be HIV positive. Among the studied variables, the age, education level, residency, donation type, and serologic status for anti-HBc and VDRL tests were found to be associated with HIV infection. Conclusions The younger, spontaneous donor candidates living in the Recife metropolitan area with a low level of education and positive for anti-HBc and VDRL have an higher risk of HIV infection than the other candidates. Data such as these are useful to understand the dynamics of infection and to guide healthcare policies.

Comparação de duas metodologias multivariadas no estudo de similaridade entre fragmentos de Floresta Atlântica

The objective of this work was to compare two multivariate methodologies in similarity studies among Atlantic Forest fragments. A bibliographical survey was carried out, and databanks were set up from 11 fragments of Atlantic Forest located in the States of Pernambuco, Rio Grande do Norte, Minas Gerais, Sao Paulo and Rio de Janeiro. The study of the floristic similarity was constructed using two methodologies of the multivariate analysis. For the usual methodology, a binary matrix (presence/absence) of 236 tree species present in the 11 fragments was used. A cluster analysis was applied using the simple linkage method and the Jaccards coefficient. In the proposed methodology, the principal components analysis was used for reducing the size of the density matrix and absolute dominancy of the 236 tree species, using the principal component scores to apply the cluster analysis by the Euclidean distance single linkage method. Two groups were identified; one in the Northeastern Region (Pernambuco) and another in the Southeastern Region (Minas Gerais). The proposed methodology identified only one group with fragments in the Northeastern region (Pernambuco), standing out that the quantitative variables are of utmost importance for the association of forests in different regions. The proposal methodology has potential for use in the study of forest fragment similarity.