Exploring the differences between sole silages of gramineous forages and mixed silages with forage legumes using 16S/ITS full-length sequencing

Silage Characteristics of Selected Forage Maize Varieties Harvested in Sole and Forage Legume Mixtures

The present study was conducted to evaluate the ensiling characteristics of selected forage maize varieties harvested in sole and forage legume mixtures. Two different forage maize varieties were harvested in different forage systems, that is, sole maize, maize + common vetch and maize + lablab intercrops, and ensiled in small-scale silos. After ensiling, samples were collected to examine the nutrient composition, fermentation quality and microbial population. Ensiled forage varieties harvested in sole forage systems had a significantly (p < 0.05) lower dry matter and crude protein contents (31.18% and 7.15% DM, respectively) than that from forage legume mixtures. Forage legume mixtures had significantly (p < 0.05) lower neutral detergent and acid detergent fibre contents (24.42% and 35.53% DM, respectively) and higher water-soluble carbohydrates (12.34% DM) in silage of selected varieties than sole forage systems. The pH value and ammonia nitrogen content of ensiled forage varieties were lower, while lactic acid production (7.25% DM) was greater in forage legume mixtures than in sole forage system. Lower acetic and propionic acid and higher butyric acid contents (1.06%, 0.84% and 0.46% DM, respectively) were observed in sole forage system for silage of selected varieties compared to forage legume mixtures. Sole forage systems showed lower numbers of lactic acid bacteria and higher populations of enterobacteria (4.31 and 4.34 log10 cfug-1, respectively) in silages of selected varieties than forage legume mixtures. The study concluded that ensiling forage materials harvested in forage intercrops have a positive effect on the silage quality. Therefore, the recommended forage system for ensiling is forage legume mixtures.

Effects of sorghum varieties on microbial communities and volatile compounds in the fermentation of light-flavor Baijiu

Light-flavor Baijiu (LFB) fermentation is a representative spontaneous mixed-culture solid-state fermentation process in which sorghum is used as the raw material. Raw materials and microorganisms are crucial to the flavor formation and quality of LFB. However, the microbial and physicochemical dynamics of different sorghum varieties during LFB fermentation, as well as their impact on flavor compounds are still largely unknown. Herein, PacBio single-molecule real-time (SMRT) sequencing and headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry (HS-SPME-GC-MS) were applied to investigate microbial community succession and volatile flavor formation in glutinous/non-glutinous sorghum-based fermented grains during LFB fermentation. Fermented grains made of glutinous sorghum Liangnuo No. 1 (GLN) had higher bacterial α-diversity and lower fungal α-diversity than those with fermented grains prepared with non-glutinous red sorghum (NRS) (p < 0.05). The dominant microbial species were Saccharomyces cerevisiae, Acetobacter pasteurinus, and Lactobacillus helveticus, the latter two of which were the predominant bacteria observed at the end of fermentation in GLN and NRS, respectively. Moisture content and reducing sugar had a more significant impact on the microorganisms in GLN, while amino acid nitrogen, total free amino acids, and residual starch were the main driving factors driving the microbial community in NRS. The correlation network and discriminant analysis indicated that a relatively high content of 4-vinylguaiacol showed a significant positive association with significant differential microbial species in GLN. These results provided valuable insights for improving the quality of LFB.

Fermentation Profile, Aerobic Stability, and Chemical and Mineral Composition of Cactus Pear Silages with Different Inclusion Levels of Gliricidia Hay

Cactus pear is used in large proportions in diets for small ruminants in semiarid regions. However, its exclusive use is not recommended due to the low fiber and crude protein content and the high water and mineral content, leading to metabolic disorders, low dry matter intake, and weight loss. The use of mixed cactus silage associated with protein and fibrous sources seeks to overcome the deficits in dry matter, fiber and crude protein, aiming to improve the nutritional quality of the diets that will be offered to ruminants. Thus, the use of gliricidia hay in cactus pear silages could represent an important alternative to improve the nutritional and fermentative characteristics of the ensiled material. Therefore, our aim was to evaluate the fermentation dynamics, nutritional characteristics, and aerobic stability of mixed silages of cactus pear combined with different levels of gliricidia hay. This was a completely randomized experimental design with five treatments and five repetitions. The treatments consisted of different levels of inclusion of gliricidia hay (0, 10, 20, 30, and 40% on a dry matter basis) in the composition of mixed cactus pear silages. The inclusion of gliricidia hay in the composition of mixed silages of cactus pear resulted in a quadratic effect for dry matter recovery, pH, NH3-N, buffering capacity, aerobic stability, ether extract, P, K, Na, and Zn (p < 0.05). There was a reduction in density, effluent losses, maximum pH, mineral matter, non-fiber carbohydrates, Ca, Mg, Fe, and Mn (p < 0.05), and an increase in the time to reach maximum pH as well as an upward trend in pH, dry matter, organic matter, crude protein, neutral detergent fiber, acid detergent fiber, and B (p < 0.05). Under experimental conditions, the inclusion of gliricidia hay between 20 and 30% in cactus pear-based silage provided an improvement to the chemical composition and fermentation parameters of the silages.