Transcriptome profiling of ruminants fed with a micronutrient-supplemented diet

Iodine (I) is a micronutrient essential for the proper thyroid functionality in mammals. I requirement is dependent by the life stage and milk constitutes the main source of I intake for infant. For this reason, in dairy ruminants, the calibration of I is fundamental to keep the performance high. However, the effects of I supplementation on gene expression in dairy cow are not well documented. Thus, to improve knowledge in this field, we have assessed the effect of I supplementation dairy cattle using RNAsequencing. In detail, we have randomly divided 22 dairy cows into two groups: the first group (CTR, 11 animals) received a customised diet with physiological level of I2 (20 mg/day/animal of I2) while the second one (I, 11 animals) received the same diet with a I2 supplementation (20 + 65 mg/day/animal of I2) for 8 weeks (56 days). At the end of supplementation, the whole blood from both groups is been collected and the transcriptome analysis is been performed. Filtering our data using a FDR <0.05, we identified 525 differentially expressed genes (DEGs) and in particular there were 274 and 248 genes downregulated and upregulated respectively in I group compared to the CTR one; they were sufficient to discriminate the two groups on a heat map scale but also on a hierarchical clustering analysis indicating the robustness of the experimental strategy. Next, we used our DEGs to evaluate the enrichment for any GO and thus identify a number of genes that share the same characteristic. Thus, we found that the most enriched pathway was associated with antigen processing and presentation o via MHC class I (GO:0002474), glycolytic process (GO:0006096), oxidation-reduction process (GO:0055114), regulation of cell proliferation (GO:0008285) indicating that iodine could positively influence the immune response and the productive performance of the animals. Moreover, our findings contribute to the growing body nutrigenomics research in ruminants.