Heat stress induces specific methylation, transcriptomic and metabolic pattern in dairy cows and their female progeny.

A heat stress (HS) cattle research design was implemented to study HS effects on the three different "omics features" methylations, gene expressions and metabolic pattern from a direct perspective in pregnant cows and from an indirect time-lagged intergenerational perspective in offspring (the respective F1 and as F1 offspring before calving). In this regard, a total number of 88 German Holstein dairy cows and their 93 female calves were blood sampled for DNA and RNA extraction and for metabolic phenotyping, and allocated to HS and respective control groups (the cows (dams) as well as their calves) according to a temperature-humidity threshold of 60. Separate principal component analyses for all "omics-tiers" revealed clear separations of HS from respective control groups, as well as dam-offspring separations according to gene expressions and metabolic pattern. The GO enrichment analyses based on the differentially expressed genes contributed to the detection of 10 significantly overrepresented biological processes in heat stressed dams, and of 95 overrepresented biological processes due to indirect maternal heat stress in calves. With regard to direct HS in dams and the first PCs of the different "omics" features, the correlation coefficient was 0.45 between methylation and gene expression data, 0.62 between expression and metabolites, and 0.38 between methylation and metabolite data. The separation of HS from the control group was very obvious when using the average and weighted average of the first and second components from the three multi-omics datasets. The present study provides extended insights into the complex genetic and physiological mechanisms of HS response in dam and calf groups from different generations, contributing to a deeper understanding of the interplay of prompt and time lagged HS effects between different omics-tiers.