GWAS analyses reveal QTL in egg layers that differ in response to diet differences

Area of Science:

• Animal Genetics
• Quantitative Genetics
• Poultry Science

Background:

• The genetic basis of egg production and quality traits in chickens remains largely unknown, with limited genes identified despite numerous quantitative trait loci (QTL) studies.
• A high-density 600K SNP chicken array provides enhanced resolution for QTL localization and discovery, moving beyond simple additive effects.

Purpose of the Study:

• To identify QTL influencing laying traits in chickens using a high-density SNP chip.
• To investigate the influence of diet and age on the effects of these QTL and explore genotype-environment interactions.

Main Methods:

• Utilized a 600K Affymetrix Axiom HD genotyping array for high-density single nucleotide polymorphism (SNP) analysis.
• Analyzed 16 different laying traits across various diets and ages at egg collection.
• Detected and mapped 131 QTL across chicken chromosomes, excluding 16 and 25.

Main Results:

• 131 QTL were identified for 16 laying traits, with individual QTL explaining 2-10% of trait variance.
• Chromosomes 3, 9, 10, and Z showed a higher concentration of QTL.
• 60 QTL exhibited significantly different effects based on diet or age, indicating substantial genotype-environment interactions.

Conclusions:

• Numerous QTL influence egg production and quality, with their effects varying based on environmental conditions (diet, age).
• Genomic regions associated with adaptation in layer chickens for egg production differ across environments.
• Future research should focus on the impact of these genotype-environment interactions on selective breeding strategies.