Effects of supplementation with Lactobacillus plantarum 299v on the performance, blood metabolites, rumen fermentation and bacterial communities of preweaning calves

Abstract The aim of the study was to evaluate whether oral administration of Lactobacillus plantarum 299v (LP299v) would have positive effects on the performance, blood metabolites, rumen fermentation and bacterial communities of preweaning calves. Twenty-four Holstein calves (3 days old; 41.87 ± 1.98 kg body weight (BW)) were grouped by BW and thereafter randomly allocated to 1 of 2 treatment groups: (1) an untreated control group (the CON group) or (2) a group treated with daily dose of 1 × 1010 cfu per calf (the LP299v group). LP299v was fed to the calves daily through mixing with the milk in the morning feeding. The experiment was finished before the calves were weaned and the relevant indicators from samples collected were detected. The results showed that feeding LP299v not only tended to decrease the fecal score (P = 0.09) and fecal pH (P = 0.07) but also decreased (P = 0.02) the diarrhea incidence of calves. Conversely, significant increases in starter intake (P = 0.03) and average daily gain (P = 0.04) were observed in LP299v-fed calves. The age at which starter intake reached 900 g per day for 3 consecutive days of calves was significantly (P = 0.04) advanced after feeding LP299v. Feeding LP299v to calves not only tended to increase the plasma concentration of immunoglobulin G (P = 0.07) but also increased the concentrations of glucose (P = 0.003), total superoxide dismutase (P = 0.02), immunoglobulin A (P = 0.01), interferon-γ (P = 0.02) and soluble CD4 (P = 0.02). However, the plasma concentrations of cholesterol (P = 0.06) and interleukin-6 (P = 0.03) were lower in LP299v-fed calves compared to those in CON calves. Moreover, trends toward increased ruminal concentration of butyrate (P = 0.08) and increased concentration of microbial protein (P = 0.04) were observed in LP299v-fed calves. The relative abundance of Bacteroidetes in the feces was higher (P = 0.03) in the LP299v group (50.7%) than in the CON group (33.0%). However, the relative abundances of Firmicutes (P = 0.04) and Proteobacteria (P = 0.07) in the feces were lower in LP299v-fed calves (CON vs. LP299v, 46.3% vs. 35.3%, 15.3% vs. 10.3%, respectively). The Simpson (P = 0.02), Chao1 (P = 0.01) and Ace (P = 0.03) indices in the feces were higher in LP299v-fed calves. These results indicated that preweaning calves fed LP299v exhibited increased growth performance and antioxidant and immune capacity, decreased diarrheal incidence, and diversified fecal bacterial community composition.