DNA methylation patterns in peripheral blood mononuclear cells from Holstein cattle with variable milk yield

Area of Science:

• Animal Genomics
• Epigenetics
• Dairy Science

Background:

• Holstein cow milk yield has significantly increased over decades due to genetic selection and management.
• The underlying molecular mechanisms driving this yield increase remain largely unknown.
• Epigenetic modifications, specifically DNA methylation, are proposed as a key factor influencing milk yield variation.

Purpose of the Study:

• To characterize genome-wide DNA methylation patterns in Holstein dairy cows with diverse milk yields.
• To establish a reference methylome for cattle, focusing on peripheral blood mononuclear cells (PBMC).
• To investigate the relationship between DNA methylation and milk production phenotypes.

Main Methods:

• Whole genome Methylation-by-DNA-Immunoprecipitation sequencing (MeDIP-seq) was employed.
• DNA was extracted from PBMC of 6 lactating Holstein cows with milk yields ranging from 13,556 kg to 23,105 kg per 305-day lactation.
• Analysis focused on genome-wide methylation, gene-specific patterns, repetitive elements, and differentially methylated regions (DMRs).

Main Results:

• Genome-wide DNA methylation patterns were described across 13,677 protein-coding genes.
• Methylation levels were generally low upstream of transcription start sites (TSS) and varied across exons and introns.
• 72 differentially methylated regions (DMRs) were identified between high-yield and control cows, with 252 DMRs found across different herd environments.

Conclusions:

• The generated reference methylome serves as a valuable resource for studying DNA methylation and phenotype relationships in selected cattle populations.
• The identification of DMRs in cows with varying milk yields indicates the potential to utilize epigenetic variation in cattle improvement strategies.
• Epigenetic insights can contribute to enhancing dairy cattle productivity and breeding programs.