Unraveling the Potential Impacts of Early Nutritional Supplementation on the Plasma Proteome of Nellore Calves

High Resolution Image Download MS PowerPoint Slide There is a lack of research investigating the molecular mechanisms underlying the effects of creep-feeding in Nellore cattle ( Bos indicus ), the predominant genetic group in the Brazilian beef herd. The objective of this research was to identify possible differences in plasma protein abundance, biological processes, and metabolic pathways between control and supplemented Nellore calves receiving an energy-protein diet during the suckling phase. Ninety-six intact male calves, offspring of four different sires, were allocated into two groups: MS (without creep-feeding, n = 48) and CF (with creep-feeding, n = 48). Plasma proteomic analyses were performed using label-free LC-MS/MS on blood samples randomly collected at weaning from six animals per group. Spectra were processed for total protein identification. Partial least squares discriminant analysis (PLS-DA) was applied to verify statistical separation between groups, and the t- test was used to identify differentially abundant proteins (DAPs). Protein–protein interaction (PPI) analysis and functional enrichment of biological processes and signaling pathways were performed. Significant differences ( p < 0.05) were found between groups at weaning (CF > MS) for body weight, average weight gain, and ribeye area, while plasma urea concentration tended to differ ( p = 0.065). Groups clustered ( p < 0.05) based on the abundance of 84 identified proteins, of which 44 showed significant differences (log 2 Fold Change ≥ |1.0| and adjusted p ≤ 0.05). PPI and enrichment analyses revealed strong connectivity among DAPs and their involvement in various biological processes and pathways related to energy, lipids, muscle, and immune metabolism. Notable pathways included “Regulation of Insulin-like Growth Factor (IGF) transport and uptake by Insulin-like Growth Factor Binding Proteins (IGFBPs)” (Reactome: R-BTA-381426) and “Regulation of actin cytoskeleton” (KEGG: bta04810). Proteins such as AHSG, APOA1, APOA2, SERPIND1, CFI, C5, C7, C9, CFB, and GSN, directly or indirectly, may contribute to explaining the observed metabolic differences inherent to muscle growth and development between groups.