Different milk diets have substantial effects on the jejunal mucosal immune system of pre-weaning calves, as demonstrated by whole transcriptome sequencing.

There is increasing evidence that nutrition during early mammalian life has a strong influence on health and performance in later life. However, there are conflicting data concerning the appropriate milk diet. This discrepancy particularly applies to ruminants, a group of mammals that switch from monogastric status to rumination during weaning. Little is known regarding how the whole genome expression pattern in the juvenile ruminant gut is affected by alternative milk diets. Thus, we performed a next-generation-sequencing-based holistic whole transcriptome analysis of the jejunum in male pre-weaned German Holstein calves fed diets with restricted or unlimited access to milk during the first 8 weeks of life. Both groups were provided hay and concentrate ad libitum. The analysis of jejunal mucosa samples collected 80 days after birth and four weeks after the end of the feeding regimes revealed 275 differentially expressed loci. While the differentially expressed loci comprised 67 genes encoding proteins relevant to metabolism or metabolic adaptation, the most distinct difference between the two groups was the consistently lower activation of the immune system in calves that experienced restricted milk access compared to calves fed milk ad libitum. In conclusion, different early life milk diets had significant prolonged effects on the intestinal immune system.