Dynamics of the Fermentation Products, Residual Non-structural Carbohydrates, and Bacterial Communities of Wilted and Non-wilted Alfalfa Silage With and Without Lactobacillus plantarum Inoculation

The aim of this study was to investigate effects of wilting and Lactobacillus plantarum inoculation on the dynamics of the fermentation products, residual non-structural carbohydrates, and bacterial communities in alfalfa silage. Fresh and wilted alfalfa were ensiled with and without L. plantarum for 10, 30, 60, and 90 days. A high-throughput sequencing method for absolute quantification of 16S rRNA was adopted to determine the bacterial community composition at different ensiling periods. For the wilted silage, the bacterial community, pH value, and ammonia nitrogen concentration remained stable in the silage at 30 days. L. plantarum inoculation accelerated lactic acid fermentation and altered the predominant genus in the wilted silage as compared with the non-inoculated group. For the non-wilted group, fast consumption of water-soluble carbohydrates (WSCs) was observed at 10 days in the non-inoculated silage along with rapid growth of undesirable Hafnia. L. plantarum inoculation inhibited growth of Hafnia at 10 days in the non-wilted silage. Clostridia fermentation occurred in the non-wilted silage at 90 days, as indicated by an increased pH, formation of butyric acid (BA), and apparent abundance of genera belonging to Clostridia. L. plantarum inoculation inhibited BA accumulation and growth of Garciella in the non-wilted silage at 90 days as compared with the non-wilted silage without inoculation, but had little effect on the growth of Clostridium sensu stricto. Overall, the high moisture content of the non-wilted alfalfa silage led to rapid consumption of WSCs and growth of harmful microorganisms at the early stage of ensiling, resulting in poor fermentation quality. Wilting and L. plantarum inoculation both improved fermentation quality and inhibited the growth of spoilage microorganisms in alfalfa silage, while L. plantarum inoculation alone failed to achieve optimum fermentation quality of non-wilted alfalfa silage.

Effects of Urea Supplementation On The Nutritional Quality And Microbial Community of Alfalfa (Medicago Sativa L.) Silage

The objectives of this study were to evaluate the contribution of urea on the nutritional quality and microbial community of ensiled alfalfa (Medicago sativa L.). Alfalfa silage was control group without urea (AL), supplementation with 0.5 % urea (AU1), or supplementation with 1 % urea (AU2). The silage tanks were opened and sampled after silage at 0, 15, 30, and 60 d. Results showed that AU2 had higher pH, ratio of NH3-N/TN and CP content than those in AL and AU1 while AU1 had higher ADF than that in AL and AU2 after 15 d silage. Richness and diversity indices of microbial communities in silage were no significant differences among AL, AU1 and AU2 group. Proteobacteria (58.23%) and Firmicutes (40.95%) were the predominant phylum in three groups during the silage process. The percent of community abundances on genera level of Enterobacteriaceae (37.61%) and Klebsiella (41.78%) in AL were a little higher than those in AU1 (30.39%, 25.02%) and AU2 (33.48%, 26.92%). These results showed that silage with urea alone could not improve the quality of alfalfa.

Effects of Lactic Acid Bacterial Inoculants on Fermentation Quality, Bacterial Community, and Mycotoxins of Alfalfa Silage under Vacuum or Nonvacuum Treatment

To investigate the effects of lactic acid bacterial (LAB) inoculants and vacuuming on the fermentation quality and bacterial community, alfalfas were ensiled with or without a commercial LAB YX or Lactobacillus plantarum strain ZZUA493 for 10, 30, 60, and 90 days while undergoing either vacuum (V) or nonvacuum (NV) treatment. At 90 days, analysis of the microbial community by high-throughput sequencing was performed, and contents of aflatoxin B1 and deoxynivalenol (DON) mycotoxins in alfalfa silage were determined. In all inoculated alfalfa silage, irrespective of V or NV treatment, lactic acid (LA) content increased, pH (p < 0.05), and ammonia nitrogen (p < 0.05) content decreased, and no butyric acid was detected. Lactobacillus or Pediococcus became the dominant genus, and the abundance of Garciella decreased in alfalfa silage with the addition of either inoculant. The LAB inoculants YX and ZZUA493 helped reduce the mycotoxin content in alfalfa silage. The abundance of Garciella in the control and DON content in all alfalfa silage groups were higher (p < 0.05) in NV than V. In summary, LAB inoculants and vacuuming had a positive influence on alfalfa silage quality, and LAB inoculants were effective in reducing mycotoxins in silage alfalfa.

Influence of lactic acid and cellulolytic bacteria on the physicochemical parameters of alfalfa silage

The study is aimed at studying the effect of a microbiological preparation consisting of lactic acid bacteria, thermophilic streptococci and cellulolytic bacteria on the quality of alfalfa silage with different dry matter content. Determined pH, content of organic acids, dry matter and nutrients, including carbohydrates. Inoculant application increased crude protein, crude fat and crude fiber and reduced water-soluble carbohydrates in silage. The preservation of nutrients in the test samples was higher than that of the control. pH corresponded to optimal values; however, lactic acid fermentation proceeded more intensively in the sample with an increased dry matter content.

Aerobic stability of alfalfa silage and methods of its improvement

Alfalfa is a non-silage crop, the silage of which became possible after the effect of drying was detected. A special feature of alfalfa is the intensive proteolysis that occurs during silage, and the prolonged development of undesirable microflora due to the slow acidification of feed. The objective of the research was to determine the effectiveness of the use of Biotrof, Biotrof 111, Biotrof 2+ and Biotal Axfast NS Gold in the silage of dried (37.07% SV) alfalfa mass. It was found that the use of these drugs contributed to the rapid acidification of feed to a pH of 3.97-4.08, against a pH of 4.96 in silage without additives, which led to the suppression of the vital activity of undesirable bacteria, a decrease in the breakdown of nutrients to gaseous products by 1.7-2.3 times and the accumulation of ammonia by 1.5-4.0 times. Due to the high resistance of alfalfa silage to aerobic spoilage, the use of bacterial preparations did not lead to an improvement in the aerobic stability of the silage, but by restraining the development of some yeasts, including pathogenic ones, and fungi of the Aspergillus sp. species, it helped to improve the sanitary status of the feed. Yeasts of the genera C. gattii and D. hansenii serve as marker organisms, an increase in the number of which indicates the occurrence of aerobic spoilage in the feed.