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3 results on '"covariance components"'

1. On intraclass structure estimation in the growth curve model.

Author

Kopčová, Veronika and Žežula, Ivan

Subjects
INTRACLASS correlation, UNIFORM spaces, STATISTICAL models
Abstract

In this paper the growth curve model, with the data correlated according to uniform structure, is considered. It represents a useful statistical model for a variety of areas. Our aim is to present various estimators of unknown variance parameters and compare their statistical properties. In the first part the review of known results for different estimators of ρ and σ 2 and their properties is given. The aim is to compare and order these estimators based on biasedness and mean square error. [ABSTRACT FROM AUTHOR]

Published
2020
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2. Genome-wide association study for semen production traits in Holstein-Friesian bulls.

Author

Suchocki, T. and Szyda, J.

Subjects
*GENOMICS, *SEMEN, *HOLSTEIN-Friesian cattle, *SINGLE nucleotide polymorphisms, *COVARIANCE matrices
Abstract

Identifying genomic regions, particularly individual genes associated with semen quality traits, may be very important for improving sire fertility via selective breeding. The aim of the study was to estimate (co)variance components and effects of single nucleotide polymorphisms (SNP) from the Illumina BovineSNP50 BeadChip (Illumina, San Diego, CA) on semen production traits and to find candidate genes for these traits. The analyzed data set originates from the Polish Holstein-Friesian dairy cattle population and consists of 1,212 bulls kept at 4 artificial insemination stations. For each bull, 5 semen production traits were collected: sperm concentration, semen volume, number of spermatozoa, motility, and motility score. A multitrait mixed model was used to estimate genetic parameters. The parameters obtained were used to estimate SNP effects for each trait separately by the mixed model, which is used in the Polish direct genomic value project. Additionally, genes located in the vicinity of significant SNP were selected as candidate genes. For motility, 20 genome-wide significant SNP, located on 12 autosomes, were identified. For sperm concentration, we found 7 significant SNP: 3 on chromosome X, and 1 on chromosomes 1, 6, 23, and 24. For semen volume and motility score, 3 and 1 significant SNP were detected, respectively. All these SNP were located on chromosome X. For the number of spermatozoa, 12 significant SNP were observed. Six SNP were located on chromosome X, 3 on chromosome 8, and 1 on chromosomes 2, 7, and 16. This study clearly indicated a key role of the X chromosome in the determination of semen quality and emphasized that including such traits into genetic evaluation should be strongly considered. [ABSTRACT FROM AUTHOR]

Published
2015
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3. Genetic Parameters of Common Wheat in Nepal

Author

Bal Krishna Joshi, Dhruba Bahadur Thapa, and Madan R Bhatta

Subjects
Randomized block design, Triticum aestivum, lcsh:S, food and beverages, Covariance, Quantitative trait locus, Heritability, Biology, Genetic correlation, Covariance components, Crop, lcsh:Agriculture, Agronomy, Genetic gain, genetic parameters, Common wheat
Abstract

Knowledge on variation within traits and their genetics are prerequisites in crop improvement program. Thus, in present paper we aimed to estimate genetic and environmental indices of common wheat genotypes. For the purpose, eight quantitative traits were measured from 30 wheat genotypes, which were in randomized complete block design with 3 replicates. Components of variance and covariance were estimated along with heritability, genetic gain, realized heritability, coheritability and correlated response. Differences between phenotypic and genotypic variances in heading days, maturity days and plant height were not large. Grain yield and plant height showed the highest phenotypic (18.189%) and genotypic (12.06%) coefficient of variances, respectively. Phenotypic covariance was higher than genotypic and environmental covariance in most of the traits. The highest heritability and realized heritability were of heading days followed by maturity days. Genetic gain for plant height was the highest. Co-heritability of 1000-grain weight with tillers number was the highest. The highest correlated response was expressed by grain yield with tillers number. This study indicates the possibility of improving wheat genotypes through selection utilizing existing variation in these traits.Journal of Nepal Agricultural Research Council Vol.1 2015 pp.9-13

Published
2015

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