Fine-mapping sequence mutations with a major effect on oligosaccharide content in bovine milk

Area of Science:

• Genetics
• Animal Science
• Biochemistry

Background:

• Human milk oligosaccharides (OS) offer health benefits to neonates.
• Oligosaccharides are minor components in bovine milk, with limited understanding of their production regulation.
• Investigating bovine milk OS is crucial for potential health applications.

Purpose of the Study:

• To measure the abundance of major oligosaccharides in bovine milk.
• To identify genetic factors regulating oligosaccharide production in the bovine mammary gland.
• To map quantitative trait loci (QTL) and candidate genes for bovine milk OS.

Main Methods:

• Genotyping 360 cows with high-density SNP markers.
• Measuring the abundance of 12 major oligosaccharides in milk samples.
• Performing genome-wide association studies (GWAS) to identify QTL and candidate genes.

Main Results:

• Most measured OS were highly heritable (50–84% h²).
• A mutation near the ABO gene explained ~80% of genetic variance for N-acetylgalactosaminyllactose and lacto-N-neotetraose.
• A QTL near ST3GAL6 explained 33% of genetic variation for 3'-sialyllactose.

Conclusions:

• Major gene effects were identified for bovine milk OS production.
• Targeted marker-assisted selection could increase specific OS levels in milk.
• This study provides the first mapping of candidate genes and causal mutations for bovine milk OS.