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Search Results: 1 - 10 of 21008 matches for " Ricardo Frederico;Verneque "
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Aspectos genéticos e ambientais da curva de lacta o de vacas da ra a Guzerá
Cobuci Jaime Araujo,Euclydes Ricardo Frederico,Teodoro Roberto Luiz,Verneque Rui da Silva
Revista Brasileira de Zootecnia , 2001,
Abstract: O conhecimento das rela es genéticas entre os parametros da curva de lacta o e a produ o de leite é importante para a sele o de vacas e de touros. Os registros de produ o de leite de 583 vacas da ra a Guzerá, filhas de 165 reprodutores, foram usados para estima o dos parametros da curva de lacta o em dois modelos matemáticos. As informa es referentes às produ es de leite foram obtidas usando-se a base de dados extraída do Arquivo Zootécnico Nacional, mantido na Empresa Brasileira de Pesquisa Agropecuária (Embrapa Gado de Leite). As análises foram efetuadas usando-se o sistema MTDFREML, sob modelo animal que incluiu os efeitos fixos de rebanho-ano-esta o de parto e, como covariável, a idade da vaca ao parto, com termos linear e quadrático. Como efeitos aleatórios foram incluídos animal, efeito permanente de ambiente e erro. As estimativas de correla es genéticas entre a produ o de leite total, a produ o inicial e a taxa de declínio da produ o foram de 0,55 e 0,86 e de -0,19 e 0,38, respectivamente, para cada modelo matemático estudado. Para as duas últimas características, estas estimativas foram de 0,45 e 0,75, indicando que vacas com maiores produ es iniciais apresentaram declínios mais acentuados da produ o de leite ao longo do período de lacta o. As correla es genéticas entre a produ o de leite em 305 dias e os parametros do modelo seguiram a mesma tendência, em magnitude e sinal, às da produ o de leite total. De acordo com os resultados, pode-se inferir que a sele o para a produ o de leite total resulta em acréscimo na produ o inicial e mudan as inexpressivas na taxa de declínio da produ o de leite, n o alterando a forma da curva de lacta o. As correla es de ordem entre as classifica es dos valores genéticos preditos foram altas e positivas (0,68 e 0,74), sugerindo que os indivíduos com os maiores valores genéticos para produ o inicial de leite seriam também aqueles com maiores valores para produ o de leite total.
Curva de lacta o na ra a Guzerá
Cobuci Jaime Araujo,Euclydes Ricardo Frederico,Verneque Rui da Silva,Teodoro Roberto Luiz
Revista Brasileira de Zootecnia , 2000,
Abstract: Os objetivos deste trabalho foram identificar as fun es matemáticas que melhor se ajustam à produ o de leite de vacas da ra a Guzerá, avaliar os efeitos dos fatores de ambiente sobre a forma da curva de lacta o e estimar parametros genéticos para a produ o de leite e para os componentes responsáveis pela forma da curva de lacta o. Foram utilizadas 1130 lacta es de 583 vacas da ra a Guzerá, filhas de 165 touros, com produ es abrangendo o período de 1983 a 1997. Os modelos y = a n e-cn, y = a - cn+ ln(n), y = a - cn e y=a e-c n foram os que melhor se ajustaram à curva de lacta o das vacas. Pela análise de variancia, verificou-se que, os efeitos de rebanho, ano de parto e idade da vaca ao parto influenciaram as características produ o de leite total, produ o inicial e taxa de declínio da produ o. Foram obtidas as estimativas para os coeficientes de herdabilidade e repetibilidade, por meio de análises com uma e duas características. A sele o de animais, baseada somente no formato da curva de lacta o, seria de baixa eficiência.
Avalia o genética de bovinos da ra a holandesa usando a produ o de leite no dia do controle
Ferreira William José,Teixeira Nilson Milagres,Euclydes Ricardo Frederico,Verneque Rui da Silva
Revista Brasileira de Zootecnia , 2003,
Abstract: Utilizaram-se 153.963 controles mensais de produ o de leite e 13.273 primeiras lacta es de vacas da ra a Holandesa, com partos entre 1989 a 1998, com o objetivo de estimar parametros genéticos, fenotípicos e de meio ambiente para produ o de leite no dia do controle (PLDC) e produ o até 305 dias de lacta o (P305), bem como verificar a conveniência de se utilizar a PLDC em avalia es genéticas, em substitui o à P305. Foram utilizados quatro modelos (modelo animal). Em dois, modelos 1 e 2, consideraram-se os controles mensais de produ o, coletados ao longo da lacta o, como medidas repetidas de um animal, diferenciados segundo o critério de forma o de grupos de animais contemporaneos. No modelo 1 (PLDCM01), as produ es dos animais foram agrupadas segundo o rebanho-ano-esta o de controle de produ o, enquanto, no modelo 2 (PLDCM02), o agrupamento considerou o rebanho-ano-esta o de parto. No modelo 3, analisaram-se os controles mensais de produ o, como características individuais (C01 até C10); e no modelo 4, analisou-se a tradicional P305. As análises foram realizadas utilizando-se o método da Máxima Verossimilhan a Restrita, por meio do sistema MTDFREML. As estimativas de herdabilidade para PLDC, com o uso do modelo 1, modelo 2 e para P305, foram de 0,27, 0,15 e 0,25, respectivamente. As herdabilidades para os controles mensais variaram de 0,11±0,02 (C01) a 0,21±0,03 (C08), e os maiores valores ocorreram a partir do quarto mês. A correla o de ordem entre os valores genéticos obtidos, para P305 e para PLDC (modelo 1), foi de 0,62, para touros, e de 0,78, para vacas. Concluiu-se que é viável a utiliza o da PLDC em estudos envolvendo a produ o de leite e que os controles do meio da lacta o, se usados para sele o, podem apresentar vantagens em rela o à P305.
Rela??o entre características morfológicas e produ??o de leite em vacas da ra?a Gir
Lagrotta, Marcos Rodrigues;Euclydes, Ricardo Frederico;Verneque, Rui da Silva;Santana Júnior, Mário Luiz;Pereira, Rodrigo Junqueira;Torres, Robledo de Almeida;
Pesquisa Agropecuária Brasileira , 2010, DOI: 10.1590/S0100-204X2010000400011
Abstract: the objective of this work was to determine genetic parameters related to morphological traits and their genetic correlation with milk yield of gir breed cows. a total of 3,805 records from 2,142 cows was used. for morphological trait analysis, the used model included the herd fixed effects, classification year and season, lactation phase and animal age at evaluation, besides the classifier identification. for milk yield, the fixed herd effects, year and season of calving and cow age at calving were included in the model. the genetic parameters were estimated using the remlf90 software. the heritability estimates varied from 0.09 to 0.54. the additive genetic variability of the majority of traits is sufficient to achieve significative annual genetic gain by selection practices. the genetic correlations among morphological traits varied from low to high and, between them and milk yield, from low to moderate. high genetic correlations among some morphological traits implies on the possibility of exclusion of some of them from the breeding program, for gir breed in brazil. the genetic correlations between milk yield and some morphological traits indicate that they may be used in the formation of selection indexes.
Aspectos genéticos e ambientais da curva de lacta??o de vacas da ra?a Guzerá
Cobuci, Jaime Araujo;Euclydes, Ricardo Frederico;Teodoro, Roberto Luiz;Verneque, Rui da Silva;Lopes, Paulo Sávio;Silva, Martinho de Almeida e;
Revista Brasileira de Zootecnia , 2001, DOI: 10.1590/S1516-35982001000500011
Abstract: the knowledge of the genetic relationships between the parameters of lactation curve and the milk yield is important for the selection of cows and sire. the records milk yield from 583 cows of the guzerá breed, daughters of 165 sire, were used to estimate the lactation curve parameters by two mathematical models. milk productions were obtained from the extracted base of data from national animal science archive maintained by national center for dairy research (embrapa gado de leite). the analyses were performed by the mtdfreml system, under animal model containing herd-year-season of calving, the linear and quadratic age effects of calving, as fixed effects animal, permanent environment and error included as random effects. the estimates of genetic correlations between the total milk yield and the initial milk yield, and the rate of decline of milk yield were 0.55 and 0.86, and -0.19 and 0.38, respectively, for each mathematical model. for last two characteristics, these estimates were 0.45 and 0.75, indicating that cows with larger initial milk yield presented accentuated milk yield declines along the lactation period. the genetic correlations among 305-days yield and the parameters of model followed the same tendency, in magnitude and sign, to the one of the total milk yield. in agreement with the results, it can be inferred that the selection for the total milk yield results in increment in the initial milk yield, and in inexpressive changes in the rate of decline of the milk yield, not altering the form of the lactation curve. the rank correlations among the classifications of the predicted genetic values were high and positive (0.68 and 0.74), suggesting that the individuals with the highest genetic values for initial milk yield, would be also those with higher values for total milk yield.
Curva de lacta??o na ra?a Guzerá
Cobuci, Jaime Araujo;Euclydes, Ricardo Frederico;Verneque, Rui da Silva;Teodoro, Roberto Luiz;Lopes, Paulo de Sávio;Silva, Martinho de Almeida e;
Revista Brasileira de Zootecnia , 2000, DOI: 10.1590/S1516-35982000000500011
Abstract: the objectives of this work were to identify the mathematical functions that better fitted the milk production of guzera breed cows, to evaluate the effects of the environmental factors on the lactation curve format and to estimate the genetic parameters for the milk production and for the dependable components of the lactation curve format. a total of 1130 lactations from 583 guzera breed cows, daughters of 165 bulls, with production over the period from 1983 to 1997 were used. the models y = a n e -cn, y = a - cn + ln (n), y=a -cn e y =a e-c n were the ones that best fitted the milk production of the cows. by the analysis of variance, it was observed that the effects of cow herd, calving year and cow age at calving influenced the total milk production, initial milk production and milk decline production rate characteristics. the coefficients of heritability and repeatability estimates were obtained by means of one and two characteristic analyses. the animal selection, based only on the of the lactation curve format, would be of low efficiency.
Estima??o de parametros genéticos de medidas de conforma??o, produ??o de leite e idade ao primeiro parto em vacas da ra?a Gir Leiteiro
Wenceslau, Amauri Arias;Lopes, Paulo Sávio;Teodoro, Roberto Luiz;Verneque, Rui da Silva;Euclydes, Ricardo Frederico;Ferreira, William José;Silva, Martinho de Almeida e;
Revista Brasileira de Zootecnia , 2000, DOI: 10.1590/S1516-35982000000100021
Abstract: abstract - data from 573 primiparous lactating gyr cows were used to estimate the (co) variance components of the conformation traits, milk production up to 305 days of lactation (mp) and age at first calving (afc) by reml method. these components were used to calculate heritability coefficients and genetic, phenotypic and residual correlations. the conformation measures, the heart girth (hg), croup height (ch), body length (bl), teats length (tl), teats diameter (td) and udder height (uh) were obtained in the cows at first lactation with average age of 4.05 years. the genetic and phenotypic correlations between mp and afc were 0.49 and 0.18 respectively. the genetic correlation between traits were mp x hg = -0.37; mp x ch = -0.62; mp x bl = -0.52; mp x tl= -0.08; mp x td= -0.12; mp x uh = -0.69; afc x hg = -0.05; afc x ch = -0.37 and afc x bl = 0.25. these estimates of genetic correlation between milk production and body size measures, in general, indicate that the selection for milk production held as a correlate response, decreasing in the cow size.
Avalia??o genética de bovinos da ra?a holandesa usando a produ??o de leite no dia do controle
Ferreira, William José;Teixeira, Nilson Milagres;Euclydes, Ricardo Frederico;Verneque, Rui da Silva;Lopes, Paulo Sávio;Torres, Robledo de Almeida;Wenceslau, Amauri Arias;Silva, Marcos Vinícius Gualberto Barbosa da;Magalh?es Júnior, Márcio Nery;
Revista Brasileira de Zootecnia , 2003, DOI: 10.1590/S1516-35982003000200007
Abstract: 153,963 test day milk yield records and 13,273 first lactations of holstein cows calving between 1989 and 1998, were used with the objective of estimating genetic, phenotypic and environmental parameters for test day milk yield (pldc) and 305 day milk yield (p305) and to study the convenience of using test day yields in genetic evaluations to replace p305. four models were used. models 1 and 2 differed according contemporary grouping and monthly milk records were considered as repeated measures. in model 1 (pldcm01) records were grouped by herd-year-season of test day yield and in model 2 (pldcm02) by herd-year-season of calving. in a third (model 3), monthly yield records were analyzed as individual traits (c01 to c10); and the fourth (model 4) was the traditional 305-day model. restricted maximum likelihood methodology was used with the mtdfreml system. the estimates of heritability for pldc, using model 1, model 2 and for p305 were 0.27, 0.15 and 0.25, respectively. heritabilities for monthly milk records ranged from 0.11+0.02 (c01) to 0.21+0.03 (c08), with the largest values occurring beginning in the fourth month. genetic correlation estimates between monthly records and p305 ranged from 0.76 to 1.00, with the highest correlations occurring in the middle lactation. it was concluded that using test day milk yield is promising and that selecting for middle lactation records could have advantages over 305-day milk yield.
Espa?o geográfico, produ??o e movimento: uma reflex?o sobre o conceito de circuito espacial produtivo
Castillo, Ricardo;Frederico, Samuel;
Sociedade & Natureza , 2010, DOI: 10.1590/S1982-45132010000300004
Abstract: the aim of this article is to demonstrate the importance and the operational feasibility of the concepts of the productive spatial circuit and cooperation circles in space, in an historical moment when the spheres of production and exchange become more scattered geographically, making circulation a priority and a strategic acting field of estates and companies. it seeks to achieve this objective through three steps: 1) elaboration of a theoretical debate based on authors that proposed and sought to develop those concepts; 2) proposition of a distinction between productive spatial circuit and productive chain; 3) a brief analysis of modern agricultural production in agricultural expansion areas in the brazilian territory in the light of this theory.
Endogamy and genetic variability in selective mating using distribution of extremes
Jangarelli, Marcelo;Euclydes, Ricardo Frederico;
Revista Brasileira de Zootecnia , 2012, DOI: 10.1590/S1516-35982012000500010
Abstract: the objective of this study was to evaluate selective mating using distribution of extremes, among other mating strategies, on its ability to decrease the endogamy and the loss of genetic variability. the genetic simulation system (genesys) was used to simulate two genomes (each one with a single characteristic whose distinction was the value of heritability) and the base and original populations. each initial population was submitted to assisted selection by markers for ten consecutive generations. for evaluation of strategies, the estimated parameters were phenotypic value, endogamy and additive genetic variance, in different family sizes, for both characteristics. in all scenarios combining heritability and family sizes, the selective mating was superior to the others, in the ability to decrease endogamy and maintain higher magnitudes of genetic variability. consequently, superior phenotypic increments were obtained, pointing to a major detection of quantitative trait loci in the assisted selection by markers due to gradual decrease of the additive genetic variance over the generations.
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