Effect of different dry matter content on fermentation characteristics and nutritional quality of Napier grass silage with novel lactic acid bacteria strains.

To investigate the characteristics of different LAB strains isolated from subtropics and their effects on Napier grass (Pennisetum purpureum Schum.) silage with two dry matter levels, sugar fermentation pattern and growth profiles of three screened lactic acid bacteria (LAB) strains [Pediococcus pentosaceus (PP04), Weissella cibaria (WC10), and Lactobacillus plantarum (LP694)] were characterized, and then used either individually or in combination at 1.0 × 106 cfu·g-1 fresh weight to inoculate grass having 15% or 25% dry matter (DM). Treatments were applied: 1) no inoculant (control); 2) PP04; 3) WC10; 4) LP694; 5) M-1 (PP04: WC10 = 2:1); 6) M-2 (PP04: LP694 = 1:2); 7) M-3 (WC10: LP694 = 2:1); 8) M-4 (PP04: WC10: LP694 = 2:1:1). The results showed that all inoculations increased LAB, DM recovery, and lactic acid concentration, while decreasing pH, the ammonia nitrogen/total nitrogen (NH3-N/TN), and butyric acid concentration compared to control group in both DM. However, the effect of inoculations was very limited at 15% DM. Silages with inoculants achieved higher silage quality at 25% DM than 15% DM. The different LAB inoculants result in significant differences in silage quality while W. cibaria decreased the pH and inhibited the growth of undesirable bacteria and those characteristics were not affected by the DM content.