Effect of packing density, bacterial inoculation, and storage length on the fermentation profile of alfalfa silage

Forage from four locations (blocks) was inoculated with 150 000 CFU/g Lactiplantibacillus plantarum DSM26571, Lactococcus lactis NCIMB30117, and Enterococcus lactis 22502 (LPEL); 150 000 CFU/g Lactococcus lactis DSM22501 and Lentilactobacillus buchneri DSM11037 (LB); or distilled water (CON), packed full (D100; 264 kg DM/m3) or half (D50; 132 kg DM/m3) density, and ensiled for 7, 14, 60, or 90 d. Data were analyzed as a randomized complete block with fixed (packing density, bacterial inoculation, storage length, and their interactions) and random (block) effects. An interaction between inoculation and storage length was observed for pH. At early storage lengths, LPEL had the lowest pH, without differences afterwards. A three-way interaction was observed for lactic acid concentration; D100 was greater than D50. An interaction between packing density and bacterial inoculation was observed for acetic acid concentration; D50-LPEL and D50-LB had the lowest acetic acid concentrations. Bacterial inoculants had minor effects, although the homofermentative inoculant decreased pH. Greater packing density increased organic acids. Thus, a combination of greater packing density and homofermentative microbial inoculants may improve fermentation and minimize storage losses. Further research is warranted to better characterize changes in the microbial community of alfalfa silage with different microbial inoculants and ensiled at different packing densities.