Phosphoproteomic Analysis of the Jejunum Tissue Response to Colostrum and Milk Feeding in Dairy Calves during the Passive Immunity Period

SIMPLE SUMMARY: The jejunum tissue is an important site of nutrient digestion and absorption in neonatal calves. However, little is known regarding the effects of colostrum and mature milk intake on protein phosphorylation in the jejunal tissue of calves during the passive immunity period. Using titanium-immobilized metal ion affinity chromatography, coupled with the liquid chromatography-tandem mass spectrometry method, we found that the phosphoproteins were differentially expressed in the jejunum tissue of the neonate after ingested colostrum and milk feeding. The parental genes were primarily involved in developmental, glycohomeostasis, and immune regulation processes. We suggest that the changes induced in phosphorylated protein expression for calves fed with colostrum may play a key role in the developmental and innate immune process. ABSTRACT: Improvements in the feeding of calves are of increasing importance for the development of the dairy industry. While colostrum is essential for the health of newborn calves, knowledge of protein phosphorylation alterations in neonatal calves that are fed colostrum or mature milk is lacking. Here, mid-jejunum tissue samples were collected from calves that received colostrum or milk. Subsequently, the jejunum phosphoproteome was analyzed using a phosphopeptide enrichment method, i.e., titanium immobilized metal ion affinity chromatography, coupled with liquid chromatography-tandem mass spectrometry. A total of 2093 phosphopeptides carrying unique 1851 phosphorylation sites corresponding to 1180 phosphoproteins were identified. Of the 1180 phosphoproteins, 314 phosphorylation sites on 241 proteins were differentially expressed between the groups. Gene ontology analysis indicated that the phosphoproteins were strongly associated with developmental and macromolecule metabolic processes, signal transduction, and responses to stimuli and insulin. Pathway analysis showed that the spliceosome, Hippo, insulin, and neurotrophin signaling pathways were enriched. These results reveal the expression pattern and changes in the function of phosphoproteins in bovine jejunum tissues under different feeding conditions and provide further insights into the crucial role of colostrum feeding during the early stages of life.