Abstract:
Favorable lactic acid bacteria (LAB) inoculants are used to enhance forage ensiling. The study aimed
to produce freeze-dried inoculants from Lactobacillus plantarum, L. rhamnosus and L. oris which
were isolated from silage of maize, sorghum and guinea grass, respectively and asses the influence
of the inoculation rate on ensiling of forage maize. The Lactobacillus isolates were inoculated
separately into MRS broth and incubated at 37ᵒ C for 18 hours (MRS mother culture). The mother
cultures were inoculated into skim milk broth (10 %) and incubated at 37ᵒ C for 72 hours. Their
growth kinetics were studied. All LAB species exceeded 109 CFU/mL by 24 h and reduced the pH
value to 3.92 – 4.11 by 72 h. Therefore, skim milk (10 %) broth was chosen as lyophilization media
for making freeze-dried LAB inoculants. Pelleted MRS mother cultures (10 mL) were dissolved in 10
% skim milk broth (30 mL) and the suspensions (0.5 mL) were freeze-dried in vials (LAB inoculant).
The effect of inoculation rate on forage maize ensiling was assessed at 3 inoculation rates (0, 104 and
106 CFU/g fresh forage). The experiment was conducted as a complete randomized design which
included 2 factors (LAB species, inoculation rate). Chopped (10-15 mm) fodder maize was treated
with respective LAB inoculant and inoculation rate. They were ensiled in I L Weck glass jars. Each
treatment combination had 3 replicates. Laboratory silos were opened at 14 days post-ensiling and
dry matter, pH value, lactic acid content and ammonia nitrogen contents were measured. The species
of LAB inoculant and inoculation rate had significant (P<0.05) effect on the pH value of maize silage.
An increasing trend of lactic acid content was evident with increasing inoculation rate of L.
plantarum. The pH value was low (P<0.05) when forage maize was inoculated with L. rhamnosus and
L. oris at 106 CFU/g rate (3.43 and 3.41), respectively. The study confirmed the potential of
production of freeze-dried LAB inoculants from L. plantarum, L. rhamnosus and L. oris that isolated
from maize, sorghum and guinea grass, respectively. Ensiling forage maize with freeze-dried L.
rhamnosus L. oris inoculants at 106 CFU/g fresh matter ensures rapid drop of pH value during
ensiling forage maize.
