Animal Molecular Breeding 2024, Vol.14, No.1, 62-71 http://animalscipublisher.com/index.php/amb 65 2.3 Limitations and challenges of GWAS research Although GWAS technology has achieved great success in revealing genetic traits, it also faces some limitations and challenges. GWAS typically require large samples to obtain statistically meaningful results, which in many cases may require a huge investment of money and time. The genetic variants identified by GWAS often explain only a small part of the variation in traits, because many complex traits (such as adaptive traits) are often affected by multiple genetic loci as well as environmental factors. Even if GWAS successfully identifies genetic markers associated with specific traits, the specific biological mechanisms underlying these markers often remain unclear. GWAS results often require further validation and interpretation through subsequent functional studies. These studies may include gene expression analyses, protein function experiments, and gene knockout or knock-in experiments to reveal how specific genetic variants affect trait expression. Although the application of GWAS in poultry genetic studies has provided a deeper understanding of the genetic basis, translating these findings into practical breeding strategies remains challenging. Genetic improvement programs need to take into account the effect sizes of genetic variants, interactions between genetic variants, and other potential non-genetic factors. GWAS technology has become a powerful tool to reveal the genetic basis of poultry adaptation. Despite limitations and challenges, it provides unprecedented opportunities and perspectives for poultry genetic research and breeding (Lee, 2021). By continuously optimizing GWAS methods and combining with other genetics and molecular biology techniques, it is expected that the genetic adaptability of poultry will be more comprehensively understood in the future, thereby guiding more effective genetic improvement strategies and improving the sustainable development capabilities of the poultry industry. 3 Poultry Genetic Improvement Strategies 3.1 Selective breeding The rapid development of the poultry industry has put forward higher requirements for poultry varieties with high production performance and good adaptability. Selective breeding, a time-honored method, has been the cornerstone of the genetic improvement of poultry. Traditional selective breeding methods focus on selecting breeders based on appearance characteristics or production performance (such as egg weight, growth rate). This method is simple, intuitive, and easy to implement, but its genetic improvement is slow and cannot directly affect the quality of chickens. genes for these traits. With the development of molecular biology, marker-assisted selection (MAS) technology has emerged. MAS provides a precise genetic selection method for breeding by identifying molecular markers associated with economically important traits. Compared with traditional breeding, MAS can more accurately identify and select individuals with desired genetic characteristics, thus accelerating the genetic improvement process (Boopathi, 2020). Genetic markers related to heat stress tolerance identified through GWAS can be used to select poultry breeds that can better adapt to high temperature environments. MAS not only improves the accuracy of selection, but also greatly shortens the breeding cycle, providing strong technical support for the rapid development of the poultry industry. 3.2 Application potential of CRISPR gene editing technology In recent years, gene editing technology, especially the CRISPR/Cas9 system, has become a revolutionary tool in genetic research and application. Compared with traditional genetic improvement methods, gene editing technology has the advantages of simple operation, low cost, and high accuracy. It can directly modify the genetic characteristics of poultry at the genetic level, thereby producing individuals with specific traits. The application potential of CRISPR technology is particularly significant in the genetic improvement of poultry. Using CRISPR technology, scientists can precisely knock out or replace specific genes related to economic traits such as disease susceptibility, growth rate, meat quality, and egg quality, thereby directly improving the
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