scholarly journals Mixed model approaches for diallel analysis based on a bio-model

1996 ◽  
Vol 68 (3) ◽  
pp. 233-240 ◽  
Author(s):  
Jun Zhu ◽  
Bruce S. Weir
Keyword(s):  
Mixed Model ◽  
Diallel Analysis ◽  
Worked Examples ◽  
Genetic Effects ◽  
Unbiased Estimation ◽  
Paternal Effects ◽  
Covariance Components ◽  
Variance And Covariance Components ◽  
Parameter Values ◽  
Estimation Of Variance

SummaryA MINQUE(l) procedure, which is minimum norm quadratic unbiased estimation (MINQUE) method with 1 for all the prior values, is suggested for estimating variance and covariance components in a bio-model for diallel crosses. Unbiasedness and efficiency of estimation were compared for MINQUE(l), restricted maximum likelihood (REML) and MINQUE(θ) which has parameter values for the prior values. MINQUE(l) is almost as efficient as MINQUE(θ) for unbiased estimation of genetic variance and covariance components. The bio-model is efficient and robust for estimating variance and covariance components for maternal and paternal effects as well as for nuclear effects. A procedure of adjusted unbiased prediction (AUP) is proposed for predicting random genetic effects in the bio-model. The jack-knife procedure is suggested for estimation of sampling variances of estimated variance and covariance components and of predicted genetic effects. Worked examples are given for estimation of variance and covariance components and for prediction of genetic merits.

scholarly journals Modeling Parent-Specific Genetic Nurture in Families with Missing Parental Genotypes: Application to Birthweight and BMI

2020 ◽  
Author(s):  
Justin D. Tubbs ◽  
Liang-Dar Hwang ◽  
Justin Luong ◽  
David M. Evans ◽  
Pak C. Sham
Keyword(s):  
Genetic Effects ◽  
Unbiased Estimation ◽  
Paternal Effects ◽  
Genetic Transmission ◽  
Nuclear Families ◽  
Genome Wide ◽  
Unbiased Estimates ◽  
Related Individuals ◽  
Missing Genotypes ◽  
The Uk

AbstractDisaggregation and estimation of genetic effects from offspring and parents has long been of interest to statistical geneticists. Recently, technical and methodological advances have made the genome-wide and loci-specific estimation of direct offspring and parental genetic nurture effects more possible. However, unbiased estimation using these methods requires datasets where both parents and at least one child have been genotyped, which are relatively scarce. Our group has recently developed a method and accompanying software (IMPISH; Hwang et al., 2020) which is able to impute missing parental genotypes from observed data on sibships and estimate their effects on an offspring phenotype conditional on the effects of genetic transmission. However, this method is unable to disentangle maternal and paternal effects, which may differ in magnitude and direction. Here, we introduce an extension to the original IMPISH routine which takes advantage of all available nuclear families to impute parent-specific missing genotypes and obtain asymptotically unbiased estimates of genetic effects on offspring phenotypes. We apply this this method to data from related individuals in the UK Biobank, showing concordance with previous estimates of maternal genetic effects on offspring birthweight. We also conduct the first GWAS jointly estimating offspring-, maternal-, and paternal-specific genetic effects on body mass index.

PRETEST HERD EFFECTS ON STATION PERFORMANCE TEST

1986 ◽  
Vol 66 (4) ◽  
pp. 925-935 ◽  
Author(s):  
A. K. W. TONG ◽  
J. A. NEWMAN ◽  
G. W. RAHNEFELD
Keyword(s):  
Fixed Effects ◽  
Mixed Model ◽  
Performance Test ◽  
Average Daily Gain ◽  
Research Station ◽  
Environmental Correlations ◽  
Warm Up ◽  
Covariance Components ◽  
Variance And Covariance Components ◽  
Daily Gain

Effects of herd of origin and the relationships between pretest and station test environments were examined from pre- and postweaning performance records of 1675 crossbred male and female calves of Hereford, Angus and Shorthorn dams, sired by 20 Charolais, 12 Simmental and 15 Limousin sires. The calves were born during 1969–1972 and raised to weaning in 45 herds from Manitoba, Saskatchewan and Alberta, and were then transported to the Brandon or the Lacombe Research Station for a 140-d postweaning performance test. Fixed effects and variance and covariance components were estimated from a mixed model which included fixed effects of herd-year, sex of calf and breed of sire and random sire effects. Herd-year effects were significant (P < 0.01) for all performance traits studied. Herd-year mean squares expressed as a percentage of the corrected total sum of squares accounted for 25.81% in the pretest period to a maximum of 54.26% in the warm-up period and then decreased to 6.78% in the 140-d period. Herd-year differences were relatively small in the later part of the test. Correlations of herd-year solutions ranged from −0.10 to 0.05 and of environments ranged from −0.09 to 0.02 between pretest average daily gain (ADG) and ADG at various test intervals. The low environmental correlations suggest that the performance of calves centrally tested at the Brandon and Lacombe Research Stations were not affected by the pre-test herd environment. Key words: Beef cattle, station test, pretest herd effects, environmental correlation

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