N. cadamba leaves, a byproduct of wood production, are always discarded in the field. N. cadamba leaves have strong antibacterial property, which might be recycled to inhibit undesirable bacteria and enhance the fermentation quality of silage. Ensiling, a traditional conservation method for animal feed, is commonly used all over the world. It is known that high-moisture forages, especially legumes, are difficult to ensile directly as much ammonia-N and butyric acid produced by undesirable bacteria will reduce the feeding value. To investigate the effects of N. cadamba leaf meal on the fermentation quality of stylo silage, 5% and 10% N. cadamba leaf meal were mixed with stylo for 30 days of ensiling in two independent experiments. Results showed that the silage pH and butyric acid content of stylo silage were decreased (p < 0.01) by 10% N. cadamba leaf meal. In experiment 2, contents of nonprotein-N and ammonia-N were significantly decreased (p < 0.05), while the true protein content was significantly increased (p < 0.05). The same results on the changing tendency were also obtained in experiment 1. In addition, N. cadamba leaf meal addition also decreased the bacterial diversity. The relative abundance of Clostridium and Lelliottia decreased, whereas that of Lactobacillus increased when N. cadamba leaf meal was added. It is worth noting that the addition of N. cadamba leaf meal also improved the antioxidant activity of stylo silage. The aforementioned results suggested that mixing N. cadamba leaf meal to high moisture forages could be an effective strategy to enhance silage fermentation quality, and it is also a feasible way to recycle N. cadamba leaves.

The presence of undesirable microorganisms in silage always leads to poor fermentation quality and low aerobic stability. Pyroligneous acid (PA), a by-product of biochar production, is known to have strong antimicrobial and antioxidant activities. To investigate the effects of PA on fermentation characteristics, aerobic stability, and microbial communities, Napier grass was ensiled with or without 1 and 2% PA for 30 days and then aerobically stored for 5 days. The results showed that PA application decreased (P < 0.01) the pH value, ammonia nitrogen content, and number of undesirable microorganisms (coliform bacteria, yeasts, and molds) after 30 days of ensiling and 5 days of exposure to air. The temperature of the PA-treated group was stable during the 5-day aerobic test, which did not exceed room temperature more than 2°C. The addition of PA also enhanced the relative abundance of Lactobacillus and reduced that of Klebsiella and Kosakonia. The relative abundance of Candida was higher in PA-treated silage than in untreated silage. The addition of PA decreased the relative abundance of Kodamaea and increased that of Monascus after 5 days of exposure to air. The abundances of Cladosporium and Neurospora were relatively high in 2% PA-treated NG, while these genera were note observed in the control group. These results suggested that the addition of PA could improve fermentation characteristics and aerobic stability, and alter microbial communities of silage.

Some excellent legume forages are difficult to ensile naturally due to their high buffering capacity and low water-soluble carbohydrate content. This may cause serious problems like proteolysis. In the present study, strains of lactic acid bacteria with high acid productivity and high tannin tolerance were screened from different silages and combined with tannic acid (TA) as an addition to ensiling. The screened strains were identified as Lactobacillus plantarum (LP), with four of these strains then selected for their high tannin tolerance. Stylosanthes guianensis and whole-plant soybean (WPS) were ensiled with 1 and 2% (fresh matter basis) TA, four LP strains alone (6 log10 colony forming units per gram of fresh matter), or TA combined with LP strains. Fermentation parameters and in vitro rumen fermentation characteristics were analyzed after 30 days of fermentation. The results showed that TA + LP can be used to reduce pH values (P < 0.01), non-protein nitrogen (P < 0.01), and ammonia-nitrogen (P < 0.01). The in vitro crude protein digestibility of WPS silage was also decreased with the addition of TA + LP (P < 0.01). These results indicate that the addition of TA combined with tannin tolerance LP strains may improve the fermentation quality of legume silage, especially for reducing proteolysis.