Short communication: Relationship of blood DNA methylation rate and milk performance in dairy cows

The objective of this study was to investigate the global methylation rate in blood DNA and its relationship with lactation performance. A total of 196 mid-lactation dairy cows were fed the same diet under the same management. Milk yield was recorded and blood samples were collected from the jugular vein before morning feeding. The blood global DNA methylation rates were quantified using a methylation quantification kit. Overall, the average blood global DNA methylation rate of all cows was 12.4%. When DNA methylation rates were compared between cows with high (n = 40; 37.0 to 42.0 kg/d) and low (n = 33; 24.0 to 30.0 kg/d) milk yield, DNA methylation rates in the lower-yield cows (14.1 ± 0.7%) were significantly higher than those in the higher-yield animals (11.6 ± 0.7%). Our results indicated an association of milk and protein yields with global DNA methylation rates in lactating dairy cows. However, further research is needed to determine whether this association reflects the true influence of epigenetic mechanisms on yield or whether other factors, such as different proportions of blood cell types in high- and low-yielding cows, affect apparent global DNA methylation levels.