Animal Molecular Breeding 2024, Vol.14, No.4, 252-261 http://animalscipublisher.com/index.php/amb 252 Review Article Open Access Quantitative Genetics in Livestock Breeding: Principles and Applications JueHuang Hangzhou Luohuashi Biotechnology Co., Ltd, Hangzhou, 310000, Zhejiang, China Corresponding email: 1298864817@qq.com Animal Molecular Breeding, 2024, Vol.14, No.4 doi: 10.5376/amb.2024.14.0026 Received: 02 May, 2024 Accepted: 20 Jun., 2024 Published: 05 Jul., 2024 Copyright © 2024 Huang, This is an open access article published under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Preferred citation for this article: Huang J., 2024, Quantitative genetics in livestock breeding: principles and applications, Animal Molecular Breeding, 14(4): 252-261 (doi: 10.5376/amb.2024.14.0026) Abstract This study explores the foundational principles of quantitative genetics, including Mendelian inheritance, polygenic traits, heritability, and genetic variance, and examines their practical applications in breeding programs. Key tools and methodologies, such as quantitative trait loci (QTL) mapping, genome-wide association studies (GWAS), and selection indices, are discussed in detail. Applications in enhancing productivity traits, improving health, and optimizing reproductive efficiency are highlighted, with a case study on dairy cattle breeding illustrating the economic and practical impacts of heritability and breeding value estimates. Emerging trends, including the integration of genomics, artificial intelligence, and CRISPR-based precision breeding, are addressed alongside challenges such as environmental interactions, ethical considerations, and the cost of advanced tools. The paper concludes by emphasizing the critical role of quantitative genetics in sustainable livestock breeding and advocating for continued research to address future challenges and opportunities. Keywords Quantitative genetics; Livestock breeding; QTL mapping; Genome-wide association studies; Heritability 1 Introduction Quantitative genetics is a branch of genetics that deals with the inheritance of traits that are determined by a large number of genes, each contributing a small effect, and are often influenced by environmental factors. These traits, known as quantitative traits, exhibit continuous variation and are typically measured on a numerical scale, such as body weight, milk yield, or egg production in livestock (Schmid and Bennewitz, 2017; Silva et al., 2017; Núñez-Torres and Almeida-Secaira, 2022). The scope of quantitative genetics extends to understanding the genetic architecture of these traits, predicting breeding values, and improving selection methods to enhance desirable traits in livestock populations (fHill, 2010; Rukundo et al., 2018). Quantitative genetics plays a crucial role in livestock breeding by providing the theoretical foundation and practical tools necessary for the genetic improvement of economically important traits. The application of quantitative genetics in livestock breeding involves the use of statistical models to predict breeding values, which are essential for selecting animals with superior genetic potential (Haley, 2002; Núñez-Torres and Almeida-Secaira, 2022). This field has significantly contributed to the efficiency of livestock production by enabling breeders to make informed decisions based on genetic data, thereby optimizing the genetic quality of livestock (Gautier, 2001; Jenko et al., 2015). Moreover, advancements in genome-wide association studies (GWAS) and genomic selection have further enhanced the ability to map and exploit quantitative trait loci (QTL) for improved breeding outcomes (Schmid and Bennewitz, 2017). This study attempts to elucidate the principles of quantitative genetics and their application in livestock breeding, discuss the importance of quantitative genetics in enhancing livestock production, and provide an overview of the latest advancements and methodologies in the field. By examining the integration of quantitative genetics with modern genomic tools, this study aims to provide insights into the future directions of livestock breeding programs and the potential for continued genetic improvement. 2 Theoretical Foundations of Quantitative Genetics 2.1 Mendelian principles underlying quantitative traits Quantitative traits in livestock are influenced by multiple genes, each contributing a small effect, which aligns with Mendelian principles of inheritance. These traits, such as body weight gain and milk production, exhibit
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