Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99


Any time

4 ( 1 )

2020 ( 2 )

2019 ( 109 )

2018 ( 221 )

Custom range...

Search Results: 1 - 10 of 87695 matches for " Luiz Otávio Campos da;Martins "
All listed articles are free for downloading (OA Articles)
Page 1 /87695
Display every page Item
Intera??o genótipo x ambiente em características de crescimento de bovinos da ra?a Nelore no Mato Grosso do Sul
Toral, Fábio Luiz Buranelo;Silva, Luiz Otávio Campos da;Martins, Elias Nunes;Gondo, Andrea;Simonelli, Sandra Maria;
Revista Brasileira de Zootecnia , 2004, DOI: 10.1590/S1516-35982004000600011
Abstract: the effect of genotype x environment interaction on body weight at birth (bw), weaning (w205), 12 (w365) and 18 (w550) months of age of nellore cattle raised in the regions of alto taquari, campo grande and pantanal, ms, brazil, was studied. the data were analyzed for each region separately and for all regions together. variance and covariance components and genetic parameters were estimated by the restricted maximum likelihood method, using an animal model that included the random additive direct effect, and the fixed effects of sex and contemporary group (herd, year, season and region of birth), and sires were ranked based on their breeding values (bv). the results showed that the additive direct and residual variances were different among regions. the heritability estimates ranged from 0.16 to 0.66 (bw), 0.36 to 0.59 (w205), 0.35 to 0.49 (w365) and 0.30 to 0.45 (w550), depending on the region. pearson's correlation coefficients between bvs of sires, obtained for each pair of regions, showed means equal to 0.11 (bw), 0.38 (w205), 0.38 (w365) and 0.39 (w550). when the correlations were for the bvs obtained for each region with the bvs obtained for all regions together, the estimates were higher showing means equal to 0.80 (bw), 0.88 (w205), 0.88 (w365) and 0.87 (w550). despite the high values of these last ones, the results show evidence of genotype x environment interaction, and that regional genetic evaluations, when available, can be more useful than a state evaluation.
Avalia??o do crescimento de bovinos jovens da ra?a Tabapu?, por meio de análises de fun??es de covariancias
Sakaguti, Eduardo Shiguero;Silva, Martinho de Almeida e;Quaas, Richard Louis;Martins, Elias Nunes;Lopes, Paulo Sávio;Silva, Luiz Otávio Campos da;
Revista Brasileira de Zootecnia , 2003, DOI: 10.1590/S1516-35982003000400011
Abstract: restricted maximum likelihood (reml) estimates of additive and residual variances and covariances for birth weight and adjusted weights at 120, 205, 240, 365, 420 e 550 days of age were used to estimate growth covariance functions (cfs) of tabapu? beef calves. data were observed on 41,415 animals born from 1975 to 1997 and raised under pasture conditions. estimation of cfs is a very useful tool to analyze beef cattle growth. it was possible to estimate covariance between any pair of ages and the analyses of eigenfunctions associated with the eigenvalues of coefficients matrix of cfs showed that the growth curves of tabapu? calves could be easily changed by selection. weaning stress, compensatory growth and selection of animals in the final period caused changes on (co)variance trajectories. therefore only cfs of more complex order were able to estimate values near to reml estimates. however, high order legendre polynomials drew sharp waves on variances trajectories at the period edges, witch does not have a coherently biological reason.
Intera??o genótipo × ambiente para produ??o de leite de bovinos da ra?a Holandesa entre bacias leiteiras no estado do Paraná
Paula, Meiby Carneiro de;Martins, Elias Nunes;Silva, Luiz Otávio Campos da;Oliveira, Carlos Antonio Lopes de;Valotto, Altair Ant?nio;Ribas, Newton Pohl;
Revista Brasileira de Zootecnia , 2009, DOI: 10.1590/S1516-35982009000300010
Abstract: it was analyzed 117,082 complete lactation records adjusted for 305 days in milk yield (my305) of 49,676 holsteins cows from 308 herds distributed among seven dairy production units in the state of paraná, brazil. the objective was to verify the genotype × environment interaction to my305 of holsteins cows between dairy production units in the state of paraná using the bayesian inference. all animals were officially controlled by the servi?o de controle leiteiro mensal of associa??o paranaense de criadores de bovinos da ra?a holandesa, between january/1992 and december/2003. the (co)variance components and genetic parameters were estimated using one and multiple-trait analysis, where my305 of each dairy production unit was considered as a different variable. means and standard deviations for my305 (kg) for dairy production units of castro, carambeí, witmarsum, arapoti, sul, norte and oeste, were 8,414 ± 1,825; 8,481 ± 2,010; 7,636 ± 1,594; 7,850 ± 1,795; 8,617 ± 2,050; 7,401 ± 1,809 and 7,336 ± 2,456, respectively. the highest heritability estimated was obtained for the oeste unit (0.39) while carambeí unit presented the lowest value (0.23). genetic correlations were low (0.09 to 0.57) between dairy production units. pearson and spearman correlations were lower for the oeste unit, when compared with other dairy production units, which ranged from 0.37 to 0.41, and from 0.37 to 0.49, respectively. these results show the presence of genotype × environment interaction between dairy production units in the state of paraná.
Estimativas de parametros genéticos para produ??o e composi??o do leite de vacas da ra?a Holandesa no estado do Paraná
Paula, Meiby Carneiro de;Martins, Elias Nunes;Silva, Luiz Otávio Campos da;Oliveira, Carlos Antonio Lopes de;Valotto, Altair Ant?nio;Gasparino, Eliane;
Revista Brasileira de Zootecnia , 2008, DOI: 10.1590/S1516-35982008000500007
Abstract: the objectives of this study were to estimate heritabilities and genetic correlations for milk (my), fat (fy) and protein (py) yields and for percentages of fat (%f) and protein (%p) in milk of holstein cows in paraná state. data consisted of 117,082 lactation records for my, fy and py and 116,747 records for %f and %p from herds supervised by the milk recording service of the holstein breeders association of paraná from january 1992 to december 2003. covariance components and genetic parameters were estimated by bayesian inference using an animal model including the fixed effects of contemporary group, number of milking, linear and quadratic effects for calving age and the additive genetic, permanent environmental and residual random effects. averages and respective standard deviations for my, fy and py (kg) were respectively 8,181.23 ± 1,903.51, 270.88 ± 67.58 and 249.01 ± 55.65 and for %f and %p they were 3.33 ± 0.45 and 3.06 0.19, respectively. heritability estimates for my, fy, py, %g and %p obtained from single-trait analyses were 0.26, 0.28, 0.25, 0.60 and 0.58, respectively. they indicate that these traits may be improved by selection. genetic correlation estimates between my and fy, my and py, fy and py, my and %f, my and %p and for %f and %p were 0.56, 0.89, 0.67, -0.42, -0.39 and 0.56, respectively. selection for increasing my will result in positive correlated genetic gains for kg of fat and protein but decrease their percentages in milk.
Herdabilidade e correla??es quanto a peso, perímetro escrotal e escores visuais à desmama, em bovinos Canchim
Barichello, Fabiana;Alencar, Maurício Mello de;Torres Júnior, Roberto Augusto de Almeida;Silva, Luiz Otávio Campos da;
Pesquisa Agropecuária Brasileira , 2010, DOI: 10.1590/S0100-204X2010000600005
Abstract: the objective of this study was to establish the best-fit model for the genetic evaluation of canchim cattle and to estimate the genetic parameters for productive characters at weaning. the data used were related to: 12,103 animals, for weight (pd); 5,278, for scrotal circumference (pe), 8,343, for slaughter conformation visual score (cf); 9,111, for sheath and navel scores (um), and 7,986, for hair coat score (pel). statistical models included fixed effects and random additive direct, maternal and maternal permanent environmental effects, in different combinations. the analyses were done by the derivative-free restricted maximum likelihood method. the complete model was the most suited for pd, pe, cf and um, while the model with only additive direct and additive maternal random effects was the best for pel. direct heritability estimates were 0.17, 0.13, 0.20, 0.18, and 0.52 for pd, pe, cf, um and pel, respectively, which indicates that it is possible to obtain genetic progress through selection for these traits, mainly for pel. the additive direct genetic correlations among traits varied from -0.16 to 0.61. the correlations between pd and pe and between pd and cf indicate that selection for pd should result in genetic gain in pe and cf
Tendência genética na ra?a Gir
Pesquisa Agropecuária Brasileira , 2000, DOI: 10.1590/S0100-204X2000000400016
Abstract: the importance of weight and weight gain for beef cattle production is responsible for the great emphasis that is devoted to these traits by breeders of different breeds. however, it is very important to maintain the animal breeding programs under surveillance in order to evaluate the genetic progress obtained by a breed as a whole. thus, this study had the objective of evaluating the genetic trends for gain up to weaning and for gain from weaning to yearling considering the direct genetic and maternal genetic effects for preweaning gain and genetic direct effect for postweaning gain. the genetic trends were estimated by the regression of the annual average expected progeny differences on birth year of the calf. positive trends were observed for preweaning gain, genetic direct and maternal genetic effect as well. this tendency was also observed for genetic direct effect for postweaning gain. the regression coefficients were 0.19, 0.06 and 0.026 g day-1, for genetic direct and genetic maternal effects for preweaning gain, and for genetic direct effect for postweaning gain, respectively.
Exigência mínina de fósforo em novilhos da ra?a Nelore
Pesquisa Agropecuária Brasileira , 2000, DOI: 10.1590/S0100-204X2000000900019
Abstract: the nutritional phosphorus (p) requirement of cattle has to consider the minimum endogenous fecal loss of this element. in general, ration formulation is based on foreign tables, without taking brazilian conditions in consideration. the aim of this study was to determine the endogenous losses of p and to estimate the minimum p requirement of nelore cattle. eighteen castrated steers aged 12 months and weighing 190.82±27.53 kg were housed in metabolism cages. in a 30 day experimental period the animals were fed with hay and a concentrate mixture. different levels of dicalcium phosphate were added to basal diet as to obtain 0.12, 0.24 and 0.36% of p, based on the total dry matter intake. 32p was intravenously injected and endogenous p losses were determined. the minimum endogenous fecal loss for zero p intake calculated by interpolation was 5.72 mg/kg (lw) per day, and for zero balance, the minimum p requirement was 8.84 mg/kg (lw) per day.
Efeitos ambientais e genéticos sobre peso, perímetro escrotal e escores de avalia??o visual à desmama em bovinos da ra?a Canchim
Barichello, Fabiana;Alencar, Maurício Mello de;Torres Júnior, Roberto Augusto de Almeida;Silva, Luiz Otávio Campos da;
Revista Brasileira de Zootecnia , 2011, DOI: 10.1590/S1516-35982011000200008
Abstract: the effects of calving year and season, property, sex of the calf, feeding regime, age of calf and age of dam at calving, maternal and direct additive effects of charolais breed, and maternal heterosis effects among charolais and zebu breeds were evaluated by the method of least squares on economical importance traits such as weight, scrotal circumference and visual scores for slaughter conformation, navel score and hair coat at weaning of the canchim breed. data from 12,334 canchim calves born from 1999 to 2005 were used. calving year and season, property, feeding regime and age of dam (linear and quadratic) had significant effects on all the studied characteristics. there were effects of sex on weaning weight and navel score; of age of the calf on weight, scrotal circumference and slaughter conformation and hair coat scores; and of proportion of charolais on the calf and on the dam on weaning weight, and on scores of slaughter conformation and hair coat; and of maternal heterozygose on weight, scrotal circumference, slaughter conformation and navel scores. additive direct effects of the charolais as deviation of zebu were negative on weight, slaughter conformation and hair coat score at weaning, while the maternal additive effects were positive. maternal heterotic effects were positive on weight, scrotal circumference, slaughter conformation and navel scores. in general, these sources of variation have to be taken into account on estimates of genetic parameters and on genetic evaluations of canchim animals for the studied characteristics.
Dissemina??o do melhoramento genético em bovinos de corte
Alves, Rafael Geraldo de Oliveira;Silva, Luiz Otávio Campos da;Euclides Filho, Kepler;Figueiredo, Geraldo Ramos de;
Revista Brasileira de Zootecnia , 1999, DOI: 10.1590/S1516-35981999000600007
Abstract: with respect to beef cattle breeding, the emphasis devoted by researchers, beef cattle producers and beef cattle experts has been, in general, focused on identification, evaluation and selection of sires. little attention has been given to the pathway used to spread the genes from such sires throughout the population as a whole. the reported low annual genetic progress observed in several herds might suggest that, in spite of having some success in promoting genetic improvement as observed in isolated herds, such dissemination occurs in a disorganized manner. such procedure might explain the observed situation where the progress accomplished by some herds is masked by the negative genetic trends observed in others. the theoretical basis of genetic dissemination in beef cattle is reviewed and some theoretical models involving the pyramidal structure of beef cattle production are analyzed, as well as the calculations of the genetic lags involved in each situation.
Desempenho de diferentes grupos genéticos de bovinos de corte em confinamento
Euclides Filho Kepler,Figueiredo Geraldo Ramos de,Euclides Valéria Pacheco Batista,Silva Luiz Otávio Campos da
Revista Brasileira de Zootecnia , 2003,
Abstract: Foram utilizadas informa es provenientes de 188 animais, pertencentes a dez grupos genéticos, avaliados em confinamento. Para as análises dos dados, os animais foram agrupados em três subconjuntos considerando-se idade, sexo e dieta recebida. Os subconjuntos analisados foram: 1) animais inteiros de sobreano recebendo a dieta "a": 39 Nelore (N), 12 Brangus (BR), 8 1/2 Simental-1/2 Nelore (SN), 8 1/2 Caracu-1/2 Nelore (CCN), 21 1/2 Valdostana-1/2 Nelore (VAN); 2) animais inteiros desmamados recebendo a dieta "b": 12 N, 12 1/2 Canchim-1/4 Angus-1/4 Nelore (CAN), 16 1/2 Canchim-1/4 Simental-1/4 Nelore (CSN), 12 1/2 Braford-1/2 Brangus (BDBR), 12 1/2 Braford-1/4 Angus-1/4 Nelore (BDAN), 7 1/2 Brahman-1/4 Angus-1/4 Nelore (BHAN); 3) fêmeas desmamadas recebendo a dieta "b" em duas formula es, uma em que o concentrado representou 30% da MS e o outro, em que o concentrado correspondeu a 50% da MS total. Neste caso, a análise incluiu 29 fêmeas, 15 CAN e 14 CSN. Para os animais dos subconjuntos 1 e 2, o concentrado foi fornecido para atender 50% da MS total da dieta. Os animais do subconjunto 1 apresentaram desempenhos semelhantes, com ganho de peso diário médio igual a 1,60 kg/dia e com convers o alimentar igual a 6,36 kg de MS ingerida/kg de ganho de peso. Para o ganho de peso diário médio e para a convers o alimentar, somente foram observadas diferen as entre os animais do subconjunto 2. O maior ganho de peso diário médio foi observado para os animais CSN (1,69 kg/dia) e as melhores convers es alimentares foram verificadas para os animais CSN e BHAN (4,76 kg de MS ingerida/kg de ganho de peso e 4,67 kg de MS ingerida/kg de ganho de peso, respectivamente). Para o subconjunto 3 n o houve diferen as entre os grupos genéticos, mas a formula o da dieta apresentou efeitos significativos importantes, especialmente, para convers o alimentar. Os animais da formula o com menor teor de concentrado apresentaram melhor convers o alimentar (5,58 kg de MS ingerida/kg de ganho de peso versus 6,66 kg de MS ingerida/kg de ganho de peso).
Page 1 /87695
Display every page Item

Copyright © 2008-2017 Open Access Library. All rights reserved.