Papers by Oscar David Múnera
Revista Colombiana De Ciencias Pecuarias, Jun 1, 2013
RESUMO-Os objetivos neste estudo foram utilizar um modelo animal multirracial para verificar a pr... more RESUMO-Os objetivos neste estudo foram utilizar um modelo animal multirracial para verificar a presença de heterogeneidade de variância genética entre as raças Angus e Nelore, avaliar a importância da variância devida à segregação entre essas duas raças e estimar os efeitos genéticos aditivos de raça, dominância e epistasia aditiva × aditiva. Foram utilizados neste estudo 4.016 registros de ganho de peso pós-desmame do rebanho de formação da raça Brangus-Ibagé da Embrapa Pecuária Sul, analisados por três modelos distintos: modelo animal multirracial com segregação, modelo animal multirracial sem segregação; e modelo animal tradicional. A heterose reduziu substancialmente em cruzamentos avançados. A variância genética média a posteriori da raça Angus (189 ± 26 kg 2) foi maior que o dobro da obtida para a raça Nelore (82 ± 23 kg 2) e a variância da segregação entre essas raças foi de 11 ± 5 kg 2. A alteração das estimativas das variâncias genéticas raciais foi insignificante quando a variância da segregação foi fixada em zero. Critérios bayesianos de escolha apontam o modelo multirracial sem segregação entre raças como uma alternativa parcimoniosa adequada para avaliação genética dessa população.
Variance components and genetic parameters for milk production of Holstein cattle in Antioquia (C... more Variance components and genetic parameters for milk production of Holstein cattle in Antioquia (Colombia) using random regression models
Revista Colombiana de Ciencias Pecuarias
Background: the genetic parameters of the lactation curve in dairy cattle can be analyzed as long... more Background: the genetic parameters of the lactation curve in dairy cattle can be analyzed as longitudinal data using Random Regression Models (RRM). Objective: to estimate the (co) variance components and genetic parameters for fat (F) and protein (P) yield in first lactation Holstein cows of Antioquia (Colombia) by RRM based on Legendre polynomials. Methods: monthly F and P records (9,479) from 1,210 first-lactation Holstein cows were used. Twenty-two and 24 RRM were used for F and P, respectively, with different orthogonal Legendre-polynomial orders to estimate the fixed-curve population coefficients and predict direct-genetic additive and permanent environment effects. The models considered homogeneous and heterogeneous residual variances of 5, 7, and 10 classes. Results: the best fit for F was the fourth order model for the population fixed-curve and the additive genetic effect, and the third order for the permanent environment with seven heterogeneous variances. The best fit fo...
Revista Brasileira de Zootecnia, 2014
The objective of this study was to evaluate lactose and milk urea nitrogen (MUN) in milk from Hol... more The objective of this study was to evaluate lactose and milk urea nitrogen (MUN) in milk from Holstein cows and their relationship with days in milk (DIM), milk yield, milk fat, milk protein, and somatic cell count (SCC). A total of 1,034 records corresponding to morning and afternoon milkings of 148 Holstein cows were used. Records were taken from 16 herds located in the Northern and Eastern dairy regions of Antioquia (Colombia). The curves were fitted using a generalized additive mixed model with smoothed estimates to find the best smoothing intensity factors involved in MUN and lactose concentration. Regarding MUN, the contemporary group effect was highly significant, but the parity effect was not significant. The DIM, lactose and milk fat smoothed covariates were highly significant, while milk yield and fat and SCC showed no statistical difference. Regarding lactose content, the contemporary group effect was highly significant, while the parity effect was not significant. Days in milk, MUN, milk fat, milk protein, and afternoon-milking SCC smoothed covariates were highly significant, while milk yield and morning-milking SCC were not significant. Lactose and milk urea nitrogen concentrations are affected by various factors throughout lactation, mainly by days in milk.
Rev. Cient.( …, 2006
Los componentes de (co)varianza y parámetros genéticos para las características de crecimiento fu... more Los componentes de (co)varianza y parámetros genéticos para las características de crecimiento fueron estimados en una población de animales cruzados, provenientes de un programa de cruzamientos alternos entre las razas Brahmán y Holstein, en dos rebaños de doble ...
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Papers by Oscar David Múnera