Peso adulto de matrizes em rebanhos de seleção da raça Nelore no Brasil

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Tendência Genética dos Efeitos Direto e Materno sobre os Pesos à Desmama e Pós-Desmama de Bovinos da Raça Tabapuã no Brasil

Os dados são relativos aos pesos de animais da raça Tabapuã, nascidos no período de 1959 a 1996 em várias regiões brasileiras. As observações foram analisadas com o objetivo de avaliar as mudanças genéticas aditivas diretas e maternas dos pesos padronizados para 205 (P205), 365 (P365) e 550 (P550) dias de idade. As estimativas dos componentes de (co) variância utilizadas no cálculo dos valores genéticos foram obtidas pelo método de máxima verossimilhança restrita livre de derivadas (REML), usando o aplicativo MTDFREML, cujo modelo continha os efeitos aleatórios aditivo direto, materno e de ambiente permanente, além dos efeitos fixos de grupo de contemporâneos (unidade da federação, fazenda, sexo, estação e ano de nascimento do animal) e a covariável idade da vaca ao parto (efeitos linear e quadrático). As tendências genéticas dos efeitos genéticos direto e materno foram estimadas pela regressão, ponderada, das médias anuais dos valores genéticos dos animais. As tendências genéticas dos efeitos direto no período estudado foram 0,134 ; 0,207, e 0,276 kg/ano, para P205, P365 e P550, respectivamente. Ainda para os três pesos, na mesma ordem, as estimativas das tendências genéticas maternas foram 0,019; -0,011; e -0,022 kg/ano. em virtude da variação genética existente, os resultados observados estão bem aquém das mudanças possíveis.

Análise de fatores genéticos e ambientais que afetam a infestação de fêmeas bovinas da raça Caracu por carrapatos (Boophilus microplus)

Este trabalho foi conduzido com o objetivo de avaliar o efeito de fatores de meio sobre a infestação de bovinos Caracu pelo carrapato Boophilus microplus (Canestrini, 1887) e estimar parâmetros genéticos do grau de infestação por esse ectoparasita. Foram realizadas contagens em fêmeas de dois rebanhos, nas quatro estações, por dois anos consecutivos (setembro/1998 a julho/2000). Contou-se o número de carrapatos (NC) em um dos lados do animal e atribuiu-se escore visual (EC) de acordo com a quantidade de carrapatos no animal. Foram feitas de uma a oito avaliações, totalizando-se 4.079 e 3.994 observações de NC e EC, respectivamente, em 718 animais. Os dados foram analisados pelo método dos quadrados mínimos com um modelo que incluiu efeitos de rebanho (R), cor do animal (C), R x C, animal dentro de R x C como erro a, ano e estação da avaliação, espessura de pelame e idade do animal como covariável. As estimativas dos componentes de variância foram obtidas pelo método da máxima verossimilhança restrita livre de derivadas, utilizando-se um modelo que incluiu os efeitos fixos de grupo de contemporâneos (fazenda-ano-época), espessura do pelame e idade do animal como covariável e os efeitos aleatórios aditivos diretos e de ambiente permanente. Antes das análises, a variável NC foi transformada para log10 (n + 1) e EC para (x + 0,5)½, em que n é o número de carrapatos contados no animal e x, o escore (0 a 4). A incidência de carrapatos foi maior no verão e, quanto maior a espessura do pelame, maior o nível de infestação. As estimativas de herdabilidade e repetibilidade foram, respectivamente, 0,22 e 0,29 para NC e 0,15 e 0,21 para EC; a correlação genética entre NC e EC foi igual a 1,00. Os resultados sugerem que é possível obter progresso genético para resistência a carrapato pela seleção.

Estimação de parâmetros genéticos para a produção de leite no dia do controle e em 305 dias para primeiras lactações de vacas da raça Holandesa

Dados de 39.578 controles leiteiros de 3.766 primeiras lactações de vacas da raça Holandesa, ocorridas de 1994 a 2002, foram analisados com os objetivos de estimar parâmetros genéticos para as produções de leite no dia do controle (PLDC) e para a produção até 305 dias de lactação (P305) e comparar estes dois critérios de seleção. Os componentes de variância foram estimados pelo método da máxima verossimilhança restrita, sob modelo animal univariado ou bivariado. Para as PLDC, os modelos incluíram o efeito aleatório genético aditivo, o efeito fixo de grupo contemporâneo e, como covariáveis, a idade da vaca ao parto (efeitos linear e quadrático) e os dias em lactação (efeito linear). Para a P305, foi utilizado o mesmo modelo, substituindo dias em lactação por duração da lactação. Os grupos de contemporâneos foram formados por ano, mês do controle e rebanho (para as PLDC) e por ano, época do parto e rebanho (para a P305). As herdabilidades estimadas para a P305 foram de 0,27 e 0,25 para as análises univariadas e bivariadas, respectivamente. Para as PLDC, as herdabilidades variaram de 0,11 a 0,31. Para o modelo bivariado (pelo qual avaliaram-se simultaneamente P305 e as PLDC), as herdabilidades para os controles (PLDC) foram menores, variando de 0,08 a 0,25. As maiores estimativas ocorreram para as produções do 4º e 5º controles, correspondendo aos 2º e 3º meses de lactação. As correlações genéticas entre P305 e os controles individuais foram positivas e elevadas, variando de 0,83 a 1,00. Os resultados indicaram que a seleção direta para P305, como tradicionalmente realizada, implicaria maiores ganhos genéticos para a produção de leite (PL) na maioria dos controles quinzenais. Além disso, a seleção direta para as produções parciais poderia proporcionar ganhos correlacionados também para a P305, mas estes ganhos seriam menores que os obtidos via seleção direta.

Estimativas de (Co)Variâncias e Tendências Genéticas para Pesos em um Rebanho Canchim

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Fatores genéticos e de meio no intervalo de partos de caprinos leiteiros

The kidding intervals (IDP) of dairy goats raised in Southeastern Brazil were studied to quantify the influence of environmental factors and to estimate genetic parameters by means of least squares (MMQ) and restricted maximum likelihood (REML). The data analyzed were obtained from five farms and three breeds (Alpine, Saanen, and Toggenburg). The overall mean and standard error of IDP, as estimated by MMQ, were 339 +/- 12.70 days. The interaction of year x season of parturition influenced IDP. In two of the years studied, goats kidding at the end of the kidding season showed a shorter IDP when compared to those that were kidding after the end of the season. A quadratic trend of IDP over years was observed across the three kidding periods. For the three seasons. IDP increased from 1986 until mid-1989 and decreased thereafter. The heritability and repeatability of IDP, as estimated by MMQ and REML, were: 0.046 +/- 0.071 and 0.103 +/- 0.043, and 0.00026 and 0.08411, respectively. These estimates indicate that little genetic gain can be expected from selection for this trait.

Genetic parameters estimate for milk and mozzarella cheese yield, fat and protein percentage in dairy buffaloes in Brazil

The aim of this study was analyze the (co)variance components and genetic and phenotypic relationships in the following traits: accumulated milk yield at 270 days (MY270,), observed until 305 days of lactation; accumulated milk yield at 270 days (MY270/A) and at 305 days (MY305), observed until 335 days of lactation; mozzarella cheese yield (MCY) and fat (FP) and protein (PP) percentage, observed until 335 days of lactation. The (co)variance components were estimated by Restricted Maximum Likelihood methodology in analyses single, two and three-traits using animal models. Heritability estimated for MY270, MY270/A, MY305, MCY, FP and PP were 0.22; 0.24, 0.25, 0.14, 0.29 and 0.40 respectively. The genetic correlations between MCY and the variables MY270, MY270/A, MY305, PP and FP was: 0.85; 1.00; 0.89; 0.14 and 0.06, respectively. This way, the selection for the production of milk in long period should increase MCY. However, in the search of animals that produce milk with quality, the genetic parameters suggest that another index should be composed allying these studied traits.

Abordagens freqüentista e bayesiana para avaliação genética de bovinos da raça Canchim para características de crescimento

This study aimed to: a) to compare the covariance components obtained by Restricted Maximum Likelihood (REML) and by bayesian inference (BI): b) to run genetic evaluations for weights of Canchim cattle measured at weaning (W240) and at eighteen months of age (W550), adjusted or not to 240 and 550 days of age, respectively, using the mixed model methodology with covariance components obtained by REML or by BI; and c) to compare selection decisions from genetic evaluations using observed or adjusted weights and by REML or BI. Covariance components, heritabilities and genetic correlation for W240 and W550 were estimated and the predicted breeding values were used to select 10% and 50% of the best bulls and cows, respectively. The covariance components obtained by REML were smaller than the a posteriori means obtained by Bl. Selected animals from both procedures were not the same, probably because the covariance components and genetic parameters were different. The inclusion of age of animal at weighing as a covariate in the statistical model fitted by BI did not change the selected bulls and cows.

Herdabilidades e Correlações Genéticas para Peso e Perímetro Escrotal de Machos e Características Reprodutivas e de Crescimento de Fêmeas, na Raça Canchim

The objective of this study was to estimate heritabilities of and genetic correlations among male body weight (BW12) and scrotal circumference (SC12) at 12 months of age, and female body weights at first (BWFC) and second (BWSC) calvings, age at first (AFC) and second (ASC) calvings, adult weight (AW), and mature weight (A) and maturation rate (k) obtained by the use of the Von Bertalanffy model. The restricted maximum likelihood method with an animal model that included the fixed effects of contemporary group and the random effects of animals, was used to estimate the variance and covariance components. The heritability estimates were equal to: 0.37 (BW12),0.30 (SC12),0.38 (A), 0.35 (k), 0.12 (AFC), 0.33 (BWFC), 0.04 (ASC), 0.39 (BWSC), and 0.38 (AW). The genetic correlations among BW12 and the female traits were: 0.19 (parameter A), 0.62 (parameter k), -0.58 (AFC), 0.69 (BWFC), -0.56 (ASC), 0.61 (BWSC), and 0.60 (AW). The genetic correlations among SC12 and the female traits were: -0.24 (A), 0.27 (k), -0.47 (AFC), 0.09 (BWFC), -0.67 (ASC), 0.07 (BWSC), and -0.17 (AW). These results indicate that male body weight and scrotal circumference and female weights (BWFC, BWSC and AW) and growth curve parameters A and k have enough additive genetic variation to respond to mass selection. Selection to increase male body weight at 12 months of age should result on favorable correlated changes in AFC, ASC and parameter k of females, but with increases in female body weights (BWFC, BWSC and AW). Selection to increase SC12 should result on desirable correlated responses in AFC, ASC and k, without any considerable change in female adult body weights.

Variances of direct genetic effects, maternal genetic effects, and cytoplasmic inheritance effects for milk yield, fat yield, and fat percentage

Milk yield, fat yield, and fat percentage during the first three lactations were studied using New York Holsteins that were milked twice daily over a 305-d, mature equivalent lactation. Those data were used to estimate variances from direct and maternal genetic effects, cytoplasmic effects, sire by herd interaction, and cow permanent environmental effects. Cytoplasmic line was traced to the last female ancestor using DHI records from 1950 through 1991. Records were 138,869 lactations of 68,063 cows calving from 1980 through 1991. Ten random samples were based on herd code. Samples averaged 4926 dams and 2026 cytoplasmic lines. Model also included herd-year-seasons as fixed effects and genetic covariance for direct-maternal effects. Mean estimates of the effects of maternal genetic variances and direct-maternal covariances, as fractions of phenotypic variances, were 0.008 and 0.007 for milk yield, 0.010 and 0.010 for fat yield, and 0.006 and 0.025 for fat percentage, respectively. Average fractions of variance from cytoplasmic line were 0.011, 0.008, and 0.009 for milk yield, fat yield, and fat percentage. Removal of maternal genetic effects and covariance for maternal direct effects from the model increased the fraction of direct genetic variance by 0.014, 0.021, and 0.046 for milk yield, fat yield, and fat percentage; little change in the fraction was due to cytoplasmic line. Exclusion of cytoplasmic effects from the model increased the ratio of additive direct genetic variance to phenotypic variance by less than 2%. Similarly, when sire by herd interaction was excluded, the ratio of direct genetic variance to phenotypic variance increased 1% or less.

Fatores genéticos e de Meio na idade ao primeiro parto de caprinos leiteiros

Data on age at first kidding (IPP) were collected on seven farms in the Brazilian Southeastern region which explored breds. Least squares (LS) were used to evaluate the effects of environmental factors and to estimate variance components, and the derivative-free restricted maximum likelihood (DFREML) method was used to estimate the variance components of IPP and to genetically evaluate the goats used in the southest region of Brazil. The LS mean and standard error of IPP were 607.18 +/- 17.09 days. The interaction of year x kidding season had a significantly influenced IPP, indicating that management conditions varied among the seasons within each specific year, with a direct influence on body weight which is the main criterion adopted by farmers to decide when the animal is ready to breed. The effect of farm-breed combination influenced the IPP. The compararison among levels of farm-breed were done by cluster analysis. The results indicated that the individual goat management within each farm had a greater influence than breed, since goats of different breeds showed high and similar values on those farms having a high mean IPP. Heritability estimates obtained by LS using intraclass correlations among paternal half-sibs and those obtained by REML were 0.220 and 0.369, respectively.

Genetic parameters estimates for milk, fat and protein yield analyzed by test day models for Murrah buffaloes in Brazil

The objectives of this study were to estimate genetic parameters for test-day milk, fat and protein yields, in Murrah buffaloes. In this study 4,757 complete lactations of Murrah buffaloes were analyzed. The (co) variance components were estimated by restricted maximum likelihood using MTDFREML software. The bi-trait animal test-day models included genetic additive direct and permanent environment effects, as random effects, and the fixed effects of contemporary group (herds-year-month of control) and age of the cow at calving as linear and quadratic covariable. The heritability estimate at first control was 0.19, increased until the third control (0.24), decreasing thereafter, reaching the lowest value at the ninth control (0.09). The highest heritability estimates for fat and protein yield were 0.23 (first control) and 0.33 (third control), respectively. For milk yield, genetic and phenotypic correlation estimates ranged from 0.37 to 0.99 and from 0.52 to 0.94, respectively. Genetic correlations were higher than phenotypic ones. For fat and protein yields, genetic correlation estimates ranged from 0.42 to 0.97.

Crystallization and X-ray diffraction data analysis of human deoxyhaemoglobin A(0) fully stripped of any anions

In this work, initial crystallographic studies of human haemoglobin (Hb) crystallized in isoionic and oxygen-free PEG solution are presented. Under these conditions, functional measurements of the O-2-linked binding of water molecules and release of protons have evidenced that Hb assumes an unforeseen new allosteric conformation. The determination of the high-resolution structure of the crystal of human deoxy-Hb fully stripped of anions may provide a structural explanation for the role of anions in the allosteric properties of Hb and, particularly, for the influence of chloride on the Bohr effect, the mechanism by which Hb oxygen affinity is regulated by pH. X-ray diffraction data were collected to 1.87 Angstrom resolution using a synchrotron-radiation source. Crystals belong to the space group P2(1)2(1)2 and preliminary analysis revealed the presence of one tetramer in the asymmetric unit. The structure is currently being refined using maximum-likelihood protocols.

Heritability Estimate and Genetic Correlations of Reproductive Features in Nellore Bulls, Offspring of Super Precocious, Precocious and Normal Cows Under Extensive Farming Conditions

The present work aimed to estimate heritability and genetic correlations of reproductive features of Nellore bulls, offspring of mothers classified as superprecocious (M1), precocious (M2) and normal (M3). Twenty one thousand hundred and eighty-six animals with average age of 21.29 months were used, evaluated through the breeding soundness evaluation from 1999 to 2008. The breeding soundness features included physical semen evaluation (progressive sperm motility and sperm vigour), semen morphology (major, minor and total sperm defects), scrotal circumference (SC), testicular volume (TV) and SC at 18 months of age (SC18). The components of variance, heritability and genetic correlations for and between the features were estimated simultaneously by restricted maximum likelihood, with the use of the vce software system vs 6. The heritability estimates were high for SC18, SC and TV (0.43, 0.63 and 0.54; 0.45, 0.45 and 0.44; 0.42, 0.45 and 0.41, respectively for the categories of mothers M1, M2 and M3) and low for physical and morphological semen aspects. The genetic correlations between SC18 and SC were high, as well as between these variables with TV. High and positive genetic correlations were recorded among SC18, SC and TV with the physical aspects of the semen, although no favourable association was verified with the morphological aspects, for the three categories of mothers. It can be concluded that the mothers sexual precocity did not affect the heritability of their offspring reproduction features.

Bayesian L-optimal exact design of experiments for biological kinetic models

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)