Genomic predictions for age at first calving and milk yield of cattle in a Thai multibreed dairy population

Name: Tawirat Konkruea

LCSH: Kasetsart University -- Dissertations. Ph.D. (Animal Science) 2019

Classification :.LCCS: SF208

LCSH: Kasetsart University. -- Department of Animal Science -- Dissertations

LCSH: Dairy cattle -- Breeding

LCSH: Dairy cattle -- Genetics

LCSH: Milk yield

LCSH: Genomes

Abstract: The objectives of this study were 1) to characterize genetic, environmental, and phenotypic variation for age at first calving (AFC) and milk yield (MY), 2) to compare prediction accuracies and rankings of animals for predicted genetic values from genomicpolygenic model (GPM) and polygenic models (PM), and 3) to compare prediction accuracies and rankings of animals for predicted genetic values from GPM using influential SNP subsets and the complete set of of GeneSeek 80K SNP chip. The dataset consisted of 8,975 Thai multibreed dairy cows from 994 dairy farms were collected AFC and MY in first-lactation, which had complete pedigree and phenotypic information. Cows were the progeny of 1,272 sires (Imported Holstein; IH and Thai Holstein; TH) sire) and 7,556 dams that calved from 1991 to 2015. Models and assumptions were defined and used differently based on the objectives. Genotyped information from 2,661 animals with GGP9K, GGP20K, GGP26K were imputed to GGP80K. The three reduced SNP sets were constructed from imputed 80K SNP include the reduced 24K, 4K, 0.3K SNP set by chosen the values SNP effect for AFC. The heritability was 0.149 for AFC, and 0.147 for MY. The genetic predictions and trends indicated that daughters of IH sires tended to have higher EBV for MY than daughters of TH sires, but daughters of both IH and TH sires tended to have similar EBV for AFC. The near zero genetic correlation between AFC and MY indicated that selection to increase MY would not affect AFC. Estimates of additive genetic variance components and heritabilities from GPM were higher than PM for AFC and MY. Mean EBV accuracies were higher for GPM (32.95% for AFC and 38.24% for MY) than for PM (32.65% for AFC, and 32.99% for MY). The heritabilities for AFC from 24K (0.22) and 4K (0.20) were higher than 80K (0.16) model. An otherwise of heritability for MY from 80K model were highest (0.25). The GEBV accuracy for AFC was continue increased from 33.26% (80K) to 37.02% (0.3K), while the GEBV accuracy for MY was continue decreased from 38.30% (80K) to 25.69% (0.3K). Rankings of all animal GEBV from every models ranged from 0.76 to 0.98 for AFC and 0.66 to 0.99 for MY. Rankings between animal GEBV from 80K and 24K had the highest correlations among sires, cows, and all animals for both traits. The result indicated that the reduced SNP set could be a feasible alternative to the complete SNP set from 80K for genomic-polygenic evaluation and selection of animals in the Thai multibreed dairy population.

Kasetsart University. Office of the University Library

Address: Bangkok

Email: tdckulib@ku.ac.th

Name: Skorn Koonawootrittriron

Role: Thesis Advisor

Name: Mauricio A. Elzo

Role: Thesis Co-Advisor

Name: Thanathip Suwanasopee

Role: Thesis Co-Advisor

Created: 2019

Modified: 2025-06-29

Issued: 2025-06-29

วิทยานิพนธ์/Thesis

application/pdf

URL: https://www.lib.ku.ac.th/KUthesis/2562/tawirat-kon-all.pdf

CallNumber: SF208 .T39

eng

DegreeName: Doctor of Philosophy

Level: Doctoral Degree

Descipline: Animal Science

Grantor: Kasetsart University

©copyrights Kasetsart University

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