Lactobacillus plantarum - INOCULATED NAPIER GRASS SILAGE ON NUTRIENT DIGESTIBILITY AND RUMEN BACTERIAL POPULATIONS IN SHEEP

This study aimed to address the optimization of fermentation and digestibility of Napier grass (Pennisetum purpureum Sch.) silage in sheep by evaluating the effects of varying levels (0%, 1%, 2%, 3%, and 4%) of Lactobacillus plantarum as a silage inoculant. A Completely Randomized Design (CRD) with six replications was employed. Sheep were housed in individual metabolic cages, with feed intake, water consumption, and waste output monitored. Rumen fluid and fecal samples were collected for microbial and proximate analysis. Results showed that dry matter digestibility (DMD) did not significantly differ among treatments (p = 0.451), although the 3% L. plantarum group (T3) exhibited the highest DMD (43.83%). Organic matter digestibility (OMD) was significantly affected (p = 0.004), with T3 recording the highest OMD (84.14%). Crude protein digestibility (CPD) showed highly significant differences (p < 0.000), with T3 and T1 achieving the highest CPD values (87.94% and 86.37%, respectively). Neutral detergent fiber digestibility (NDFD) also varied significantly (p = 0.003), with T3 again showing the highest NDFD (54.63%). In terms of rumen fermentation, L. plantarum levels significantly influenced rumen pH (p = 0.027). The initial rumen pH values were similar across groups; however, the final pH values decreased with increasing inoculant levels. The greatest reduction in pH was observed in the T4 (4%) group (9.26% decrease), followed closely by T3 (8.40%). These pH shifts corresponded to changes in rumen bacterial populations. Although initial bacterial counts were statistically similar (p = 0.462), significant reductions in final counts were observed (p = 0.001), with T3 showing the lowest population (2.36 × 10⁷ cfu/mL), indicating a potential for improved microbial modulation at this level. The study concludes that moderate supplementation with Lactobacillus plantarum, particularly at 3%, optimally enhances silage digestibility, maintains beneficial rumen pH levels, and improves microbial balance. Excessive inclusion (4%) may lead to lower fermentation efficiency due to acidic rumen conditions. Keywords: Pennisetum purpureum Sch.; fermentation; neutral detergent fiber; probiotics; ruminant nutrition; Ovis aries L.