Transcriptome analysis revealed that delaying first colostrum feeding postponed ileum immune system development of neonatal calves.

Our objective was to evaluate the effect of colostrum feeding times on genome-wide gene expression of neonatal calves. In total, twenty-seven calves were assigned to three colostrum feeding treatments: within 45 min (TRT0h, n = 9), 6 h (TRT6h, n = 9) and 12 h (TRT12h, n = 9). Ileum tissues were collected at 51 h and transcriptomic analysis was conducted. Uniquely expressed genes were identified in TRT0h group with enriched "Antigen Presentation" function. Meanwhile, the weighted gene co-expression network analysis (WGCNA) identified four significant gene modules (|correlation| > 0.50 and P ≤ 0.05). In particular, Turquoise gene module with the enriched "Cadherin binding involved in cell-cell adhesion" and "Cell-cell adherences junction" GO terms were significantly correlated with Faecalibacterium prausnitzii (R = −0.70, P < 0.01) and Bifidobacterium (R = −0.55, P < 0.01). Our findings suggest feeding colostrum without delay could stimulate the expression of genes involved in immune function development related to host response and microbial colonization in neonatal claves. • This is the first study to explore the effect of colostrum feeding times on the genome-wide gene expression in the ileum of neonatal calves. • Our findings suggested that delaying colostrum feeding to 6 or 12 h after birth postponed immune system development of neonatal claves. • Meanwhile, the relationships between bacterial population and the KEGG pathways "NOD-like receptor (NLRs)", "Toll-like receptor (TLR)" and "RIG-I-like receptors" further suggested that mucosa-attached bacteria play an important role in host immune system and gut barrier development. [ABSTRACT FROM AUTHOR]