Estimation of genetic variance and covariance components for weaning weight in Simmental cattle.

1997 ◽  
Vol 75 (2) ◽  
pp. 325 ◽  
Author(s):  
C Lee ◽  
C P Van Tassell ◽  
E J Pollak
Keyword(s):  
Genetic Variance ◽  
Weaning Weight ◽  
Covariance Components ◽  
Simmental Cattle ◽  
Variance And Covariance Components

scholarly journals Estimates for Genetic Variance Components in Reciprocal Recurrent Selection in Populations Derived from Maize Single-Cross Hybrids

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Matheus Costa dos Reis ◽  
José Maria Villela Pádua ◽  
Guilherme Barbosa Abreu ◽  
Fernando Lisboa Guedes ◽  
Rodrigo Vieira Balbi ◽  
...  
Keyword(s):  
Plant Height ◽  
Genetic Variance ◽  
Recurrent Selection ◽  
Reciprocal Recurrent Selection ◽  
Additive Variance ◽  
Lattice Design ◽  
Single Cross ◽  
Covariance Components ◽  
Variance And Covariance Components ◽  
Single Cross Hybrids

This study was carried out to obtain the estimates of genetic variance and covariance components related to intra- and interpopulation in the original populations (C0) and in the third cycle (C3) of reciprocal recurrent selection (RRS) which allows breeders to define the best breeding strategy. For that purpose, the half-sib progenies of intrapopulation (P11and P22) and interpopulation (P12and P21) from populations 1 and 2 derived from single-cross hybrids in the 0 and 3 cycles of the reciprocal recurrent selection program were used. The intra- and interpopulation progenies were evaluated in a10×10triple lattice design in two separate locations. The data for unhusked ear weight (ear weight without husk) and plant height were collected. All genetic variance and covariance components were estimated from the expected mean squares. The breakdown of additive variance into intrapopulation and interpopulation additive deviations (στ2) and the covariance between these and their intrapopulation additive effects (CovAτ) found predominance of the dominance effect for unhusked ear weight. Plant height for these components shows that the intrapopulation additive effect explains most of the variation. Estimates for intrapopulation and interpopulation additive genetic variances confirm that populations derived from single-cross hybrids have potential for recurrent selection programs.

scholarly journals Genetic variance and covariance components related to intra- and interpopulation recurrent selection in maize (Zea mays L.)

1998 ◽  
Vol 21 (4) ◽  
pp. 537-544 ◽  
Author(s):  
Carlos Alberto Arrabal Arias ◽  
Cláudio Lopes de Souza Júnior
Keyword(s):  
Zea Mays ◽  
Genetic Variance ◽  
Recurrent Selection ◽  
Zea Mays L ◽  
Inbred Lines ◽  
Additive Effects ◽  
Covariance Components ◽  
Per Se ◽  
Variance And Covariance Components ◽  
Variance Estimates

New genetic variance and covariance components related to intra- and interpopulational recurrent selection methods have been theoretically developed by Souza Jr. (Rev. Bras. Genet. 16: 91-105, 1993) to explain the failure of these methods to concomitantly develop hybrid and per se populations. Intra- and interpopulation half-sib progenies of 100 genotypes were sampled from maize (Zea mays L.) populations BR-106 and BR-105 to estimate variance and covariance components and to compare the expected responses to reciprocal (RRS), intrapopulational (HSS), and modified (MRS) recurrent selection in interpopulation hybrid, populations per se, and to determine heterosis. Four sets of 100 progenies, two intra- and two interpopulational, were evaluated in partially balanced 10 x 10 lattices arranged in split-blocks with two replications in two years (1991/92 and 1992/93) and two locations in Piracicaba, SP. Data for ear weight, plant and ear height, and ear by plant height ratio were recorded. Populations and interpopulation crosses were high yielding and showed high breeding potential for production of hybrids from inbred lines. Mid parent and the highest parent heterosis were relatively high, but lower than values reported for these populations under other environmental conditions. Additive variance estimates of populations per se and interpopulation crosses confirmed the high potential of these materials. The magnitude of the variance estimates for the deviations from intra- and interpopulation additive effects (<img src="http:/img/fbpe/gmb/v21n4/1918f1.jpg" alt="1918f1.jpg (1262 bytes)" align="middle"> for BR-106 and <img src="http:/img/fbpe/gmb/v21n4/1918f3.jpg" alt="1918f3.jpg (1259 bytes)" align="middle">for BR-105) and covariance between additive effects with these deviations (<img src="http:/img/fbpe/gmb/v21n4/1918f2.jpg" alt="1918f2.jpg (2022 bytes)" align="middle"> for BR-106 and <img src="http:/img/fbpe/gmb/v21n4/1918f4.jpg" alt="1918f4.jpg (1995 bytes)" align="middle"> for BR-105) indicated that these new components can significantly influence the effectiveness of breeding methods. Genetic component estimates for BR-105 had relatively small errors, with <img src="http:/img/fbpe/gmb/v21n4/1918f4.jpg" alt="1918f4.jpg (1995 bytes)" align="middle"> negative for all traits. Estimates of <img src="http:/img/fbpe/gmb/v21n4/1918f1.jpg" alt="1918f1.jpg (1262 bytes)" align="middle">and <img src="http:/img/fbpe/gmb/v21n4/1918f2.jpg" alt="1918f2.jpg (2022 bytes)" align="middle"> had relatively larger errors for BR-106. The MRS method was more effective than the RRS and HSS methods in producing hybrids from inbred lines. The choice of a population tester for the MRS method based on population means per se may be incorrect. The additional use, when possible, of intra- and interpopulation additive genetic variances from each population would be more appropriate.

scholarly journals Estimation of direct and maternal genetic parameters for weaning weight in Hungarian Simmental cattle

2021 ◽  
pp. 17-22
Author(s):  
Afees Abiola Ajasa ◽  
Imre Füller ◽  
Barnabás Vágó ◽  
István Komlósi ◽  
János Posta
Keyword(s):  
Fixed Effects ◽  
Genetic Parameters ◽  
Additive Genetic Variance ◽  
Random Effect ◽  
Ratio Test ◽  
Genetic Covariance ◽  
Weaning Weight ◽  
Simmental Cattle ◽  
Estimate Variance ◽  
Best Fit

The aim of the current research was to estimate variance components and genetic parameters of weaning weight in Hungarian Simmental cattle. Weaning weight records were obtained from the Association of Hungarian Simmental Breeders. The dataset comprised of 44,278 animals born from 1975 to 2020. The data was analyzed using the restricted maximum likelihood methodology of the Wombat software. We fitted a total of six models to the weaning weight data of Hungarian Simmental cattle. Models ranged from a simple model with animals as the only random effect to a model that had maternal environmental effects as additional random effects as well as direct maternal genetic covariance. Fixed effects in the model comprised of herd, birth year, calving order and sex. Likelihood ratio test was used to determine the best fit model for the data. Results indicated that allowing for direct-maternal genetic covariance increases the direct and maternal effect dramatically. The best fit model had direct and maternal genetic effects as the only random effect with non-zero direct-maternal genetic correlation. Direct heritability, maternal heritability and direct maternal correlation of the best fit model was 0.57, 0.16 and -0.78 respectively. The result indicates that problem of (co-)sampling variation occurs when attempting to partition additive genetic variance into direct and maternal components.

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