Effects of feeding silage inoculated with Lactococcus lactis and Lentilactobacillus buchneri on performance and nutrient utilization in transition dairy cows

Two experiments were conducted to assess the effect of including a mixed microbial inoculant on (1) the fermentation and nutritional value of silage in laboratory-scale silos and (2) the effects of feeding an inoculated silage-based TMR on the performance, nutrient digestibility, and ruminal fermentation in transition dairy cows from -21 d to +42 DIM. In experiment 1, harvested fresh corn forage was inoculated either with (1) double-distilled water (CON-L) or (2) mixed microbial inoculant with 1.5 × 10⁵ cfu/g of fresh forage of Lactococcus lactis O224 and Lentilactobacillus buchneri LB1819 at a rate of 30 mL/kg of fresh forage (INO-L). Adding mixed microbial inoculants under laboratory conditions had no effect on the chemical composition of the corn silage; however, the fermentation parameters and aerobic stability were improved after 90 d of ensiling. Acetate and 1,2-propanediol increased for INO-L after 90 d of ensiling (1.72% vs. 1.17% DM and 0.47% vs. 0.01% DM, respectively). Moreover, INO-L had lower yeast counts than CON-L after 90 d of ensiling (2.07 vs. 3.63 log cfu/g). Dry matter loss was lower for INO-L than CON-L (1.06% vs. 3.74%). Lastly, the INO-L treatment had greater aerobic stability than CON-L (230.8 vs. 95.1 h). For experiment 2, fresh corn and ryegrass were ensiled in Ag-Bags with (1) the control treatment, double-distilled water, or (2) the inoculated treatment, a mixed microbial inoculant with 1.5 × 10⁵ cfu/g of fresh forage of Lactococcus lactis O224 and L. buchneri LB1819 at a rate of 30 mL/kg of fresh forage, and mixed in the diets of prepartum and postpartum dairy cows. Fifty-four pregnant cows (245 ± 3 d of gestation; 768 ± 76 kg BW) were fed a TMR with control or inoculated corn and ryegrass silage (54% and 9.3% of diet DM, and 43% and 6.7% of diet DM during the prepartum and postpartum phases, respectively). Feeding TMR with inoculated silages did not affect the DMI and ruminal fermentation of prepartum cows. However, DMI tended to increase at ~4 wk postpartum for cows fed the TMR with inoculated silage. Moreover, 3.5% FCM and ECM increased for postpartum cows fed the TMR with inoculated silages (44.9 vs. 42.0 kg/d and 44.5 vs. 41.9 kg/d, respectively). Milk fat yield increased for cows fed the TMR with inoculated silages compared with those fed the TMR with control silages (1.62 vs. 1.50 kg/d). No treatment effects were observed on the total-tract apparent nutrient digestibility of prepartum cows. However, we observed a tendency to increase NDF digestibility for postpartum cows fed the TMR with inoculated silages compared with those fed the TMR with the control silages (45.2% vs. 42.0%). Prepartum cows fed inoculated silages had greater ammonia-N concentrations than those fed the TMR with the control silages (5.47 vs. 4.18 mM). No treatment differences were observed in ruminal fermentation during the postpartum phase. In conclusion, microbial additives improved the aerobic stability of preserved forages at the feed-out phase, and feeding inoculated silage-based TMR had no effects for prepartum cows but enhanced the production performance of lactating dairy cows in early lactation.