Assessment of the effect of freeze-dried Lactobacillus inoculants on ensiling fodder Sorghum and Guinea grass

Abstract

The quality of ensiled forage can be protected by using appropriate lactic acid bacteria (LAB) inoculants. The present study assessed the influence of freeze-dried Lactobacillus plantarum, L. rhamnosus and L. oris which were isolated from maize, sorghum and guinea grass silage, respectively on ensiling fodder sorghum and guinea grass. Two experiments were conducted each as a complete randomized design which included 2 factors (LAB species, inoculation rate). Each treatment combination had 3 replicates. Fodder sorghum (28.88 % DM) and guinea grass (19.29 % DM) were harvested and chopped (10 – 15 mm) and ensiled under laboratory conditions in 1L Weck glass jars. At ensiling, chopped fodder were inoculated with each LAB species at 3 inoculation rates (0, 104 and 106 CFU/g fresh fodder). The jars were opened on 14 days post-ensiling and assessed for dry matter, soluble carbohydrate, lactic acid and ammonia nitrogen contents and pH value. Fodder sorghum inoculated with L rhamnosus and L. oris at 106 CFU/g fresh fodder recorded low (P<0.05) pH values (3.48 and 3.45, respectively). However, fodder sorghum inoculated with L. rhamnosus at 106 CFU/g fresh fodder had higher (P<0.05) lactic acid content compared to L. oris (9.77 % vs. 2.95 %). Guinea grass inoculated with L. oris at 104 CFU/g fresh fodder recorded higher (P<0.05) lactic acid content (17.66 %) and the lowest (P<0.05) pH value (4.87). The study confirmed that the inoculation of fodder sorghum and guinea grass with freeze-dried L. rhamnosus and L. oris inoculants (106 CFU/g fresh fodder and 104 CFU/g fresh fodder, respectively) ensures rapid drop of pH value during ensiling, resulting in high quality of fodder silage.