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Goiânia, Brazil

Lopes F.B.,Embrapa Cerrados Capes | da Silva M.C.,Federal University of Goais | Marques E.G.,Federal University of Goais | McManus C.M.,Federal University of Rio Grande do Sul
Tropical Animal Health and Production | Year: 2012

This study was undertaken to aim of estimating the genetic parameters and trends for asymptotic weight (A) and maturity rate (k) of Nellore cattle from northern Brazil. The data set was made available by the Brazilian Association of Zebu Breeders and collected between the years of 1997 and 2007. The Von Bertalanffy, Brody, Gompertz, and logistic nonlinear models were fitted by the Gauss-Newton method to weight-age data of 45,895 animals collected quarterly of the birth to 750 days old. The curve parameters were analyzed using the procedures GLM and CORR. The estimation of (co)variance components and genetic parameters was obtained using the MTDFREML software. The estimated heritability coefficients were 0.21 ± 0.013 and 0.25 ± 0.014 for asymptotic weight and maturity rate, respectively. This indicates that selection for any trait shall results in genetic progress in the herd. The genetic correlation between A and k was negative (-0.57 ± 0.03) and indicated that animals selected for high maturity rate shall result in low asymptotic weight. The Von Bertalanffy function is adequate to establish the mean growth patterns and to predict the adult weight of Nellore cattle. This model is more accurate in predicting the birth weight of these animals and has better overall fit. The prediction of adult weight using nonlinear functions can be accurate when growth curve parameters and their (co)variance components are estimated jointly. The model used in this study can be applied to the prediction of mature weight in herds where a portion of the animals are culled before they reach the adult age. © 2012 Springer Science+Business Media B.V. Source

Gowane G.R.,Central Sheep and Wool Research Institute | Prince L.L.L.,Central Sheep and Wool Research Institute | Lopes F.B.,Embrapa Cerrados Capes | Paswan C.,Central Sheep and Wool Research Institute | Sharma R.C.,Central Sheep and Wool Research Institute
Small Ruminant Research | Year: 2015

Estimates of (co)variance components and genetic parameters were calculated for birth weight (BWT), weaning weight (WWT), 6-month weight (6WT), 9-month weight (9WT), 12-month weight (12WT), average daily gain (ADG) from birth to weaning (ADG1), weaning to 6 months (ADG2) and 6-12 months (ADG3) for Malpura sheep. Data were collected over a period of 25 years (1985-2010) with records for economic traits on total of 4549 lambs descended from 234 sires and 1541 dams of Malpura sheep maintained at Central Sheep & Wool Research Institute, Avikanagar, Rajasthan, India. Analyses were carried out by Bayesian approach using Gibbs sampler Animal model. Total heritability estimates for BWT, WWT, 6WT, 9WT, 12WT, ADG1, ADG2 and ADG3 were 0.21, 0.15, 0.17, 0.11, 0.28, 0.15, 0.22 and 0.19, respectively. Maternal genetic effects contributed significantly for total variance in the traits except 12WT and ADG3. Maternal permanent environmental effects contributed 9% of the total phenotypic variation for BWT and thereafter declined significantly for all the traits. A moderate rate of genetic progress seems possible in the flock for live weight traits by mass selection. Direct genetic correlations between body weight traits were positive and high and ranged from 0.37 for WWT and 12WT to 0.96 between 9WT and 12WT. Genetic correlations between different daily gain traits were negative due to kin and contemporary competition effect. Results suggest that genetic progress in the growth traits can be achieved if the selection is carried out for higher 6-month weight. © 2015 Elsevier B.V. Source

Lopes F.B.,Embrapa Cerrados Capes | Magnabosco C.U.,Embrapa Cerrados | Paulini F.,University of Brasilia | da Silva M.C.,Federal University of Goais | And 2 more authors.
PLoS ONE | Year: 2013

Components of (co)variance and genetic parameters were estimated for adjusted weights at ages 120 (W120), 240 (W240), 365 (W365) and 450 (W450) days of Polled Nellore cattle raised on pasture and born between 1987 and 2010. Analyses were performed using an animal model, considering fixed effects: herd-year-season of birth and calf sex as contemporary groups and the age of cow as a covariate. Gibbs Samplers were used to estimate (co)variance components, genetic parameters and additive genetic effects, which accounted for great proportion of total variation in these traits. High direct heritability estimates for the growth traits were revealed and presented mean 0.43, 0.61, 0.72 and 0.67 for W120, W240, W365 and W450, respectively. Maternal heritabilities were 0.07 and 0.08 for W120 and W240, respectively. Direct additive genetic correlations between the weight at 120, 240, 365 and 450 days old were strong and positive. These estimates ranged from 0.68 to 0.98. Direct-maternal genetic correlations were negative for W120 and W240. The estimates ranged from -0.31 to -0.54. Estimates of maternal heritability ranged from 0.056 to 0.092 for W120 and from 0.064 to 0.096 for W240. This study showed that genetic progress is possible for the growth traits we studied, which is a novel and favorable indicator for an upcoming and promising Polled Zebu breed in Tropical regions. Maternal effects influenced the performance of weight at 120 and 240 days old. These effects should be taken into account in genetic analyses of growth traits by fitting them as a genetic or a permanent environmental effect, or even both. In general, due to a medium-high estimate of environmental (co)variance components, management and feeding conditions for Polled Nellore raised at pasture in tropical regions of Brazil needs improvement and growth performance can be enhanced. © 2013 Lopes et al. Source

Lopes F.B.,Embrapa Cerrados Capes | Magnabosco C.U.,Embrapa Cerrados | Mamede M.M.,Federal University of Goais | da Silva M.C.,Federal University of Goais | And 3 more authors.
Tropical Animal Health and Production | Year: 2013

This study used multivariate statistics to identify clusters of animals with similar expected progeny difference (EPD) and also identify leading traits that discriminate between bulls. Various linear selection indices based on specific selection criteria were proposed. Records were collected from 880 young Nelore bulls submitted to performance testing in central Brazil between 2001 and 2012. Pre-weaning average daily gain and weights at 210 days with direct and maternal effects were used in the analysis, in addition to post-weaning weight, scrotal circumference at 365 and 450 days, carcass finish and rib eye area. EPDs were classified into three groups, and the EPD means of two of these groups stood out and were considered important based on principal component analysis that associated higher values of direct EPD of weights, average daily weight gain and scrotal circumference. The EPDs for weight at 210, 365 and 450 days, pre- and post-weaning daily gain and scrotal circumference at 365 and 450 days were major causes of variation. Each linear selection index proposed (SI1, SI2, SI3, SI4 and SI5) defined a specific approach meaning that a different selection index should be used depending on breeding goals and selection criteria. © 2013 Springer Science+Business Media Dordrecht. Source

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