Effects of fermented corn gluten meal on growth performance, plasma metabolites, rumen fermentation and bacterial community of Holstein calves during the pre-weaning period

The effects of fermented corn gluten meal (FCGM) on growth performance, plasma metabolites, rumen fermentation and bacterial community of Holstein calves during the pre-weaning phase were investigated in this study. Twenty Holstein calves (mean ± SEM; age = 6.89 ± 1.32 d) were offered milk replacer and then assigned to the experiment after 1 wk of adaptation. Calves (mean ± SEM; body weight = 49.3 ± 3.12 kg; age = 13.9 ± 1.32 d) were blocked for BW and age and subsequently randomly assigned to receive calf starter containing 5% corn gluten meal (CGM) or 5% FCGM (dry matter basis). The experiment lasted 6 weeks. Fermented corn gluten meal contained a lower (P < 0.05) neutral detergent fiber content but contained higher (P < 0.05) crude protein, amino acid, and small peptide content than CGM. Compared with the calves fed CGM, calves fed FCGM grew faster (P < 0.05) and tended (P < 0.10) to have higher starter intake. The incidence and severity of diarrhea were significantly less (P < 0.05) in FCGM-fed calves than in CGM-fed calves. Concentrations of plasma total superoxide dismutase, catalase, total antioxidant capacity, immunoglobulin A and interferon-γ in calves fed FCGM were significantly higher (P < 0.05) than those of calves fed the CGM. However, the levels of malondialdehyde and interleukin-6 in the plasma were significantly decreased (P < 0.05) in FCGM-fed calves. Moreover, in rumen fluids, the relative abundance of Bacteroidetes was higher in FCGM-fed calves than in CGM-fed calves (68.72% vs. 45.86%). However, the relative abundance of Proteobacteria was lower for calves fed FCGM (12.97% vs. 32.62%); in feces, calves fed FCGM had higher Firmicutes (56.09% vs. 43.01%) but lower Bacteroidetes and Proteobacteria compared with those of calves fed CGM (1.96% vs. 5.10%and 37.02% vs. 47.88%, respectively). Overall, the results indicate that calves fed FCGM during the pre-weaning period exhibited an improved growth performance, a decreased diarrheal incidence, an increased antioxidant and immune capacity, an improved rumen function together with changed bacterial community composition in the rumen fluids and feces.