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Lactic acid bacteria (LAB) should not only survive, but also perform under increased osmotic pressure in the process of ensiling, which results from the best practice of wilting forage. Simple laboratory protocols are needed to select suitable LAB strains as inoculants for high dry matter (DM) conditions. The aim of this study was to simulate conditions of high osmolality without inducing salt stress and to select a suitable indicator of LAB performance. For that, an MRS medium was enriched with increasing concentrations of glucose and fructose plus a maximum of 28 g KCl/L until achieving an osmolality of 2.4 osmol/kg. Both, growth in the inoculated medium and pH decline, were then compared to the LAB performance in the basic medium. The latter was clearly delayed in the new medium. Finally, the method was validated by comparing the pH of small-scale grass silages of 30–35 and 45–49% target DM after 3–5 days of ensiling to the pH values of the microbiological growth medium. The pH levels of treatments with the homofermentative LAB were clearly attributable to the dry matter or the sugar concentration, respectively. The developed liquid growth medium sufficiently approximates high DM conditions to select for the osmotolerant homofermentative LAB. [ABSTRACT FROM AUTHOR]

Hydrocyanic acid (HCN) is regulated in the European Union to max. 57 mg/kg dry matter (DM) in complete feed. The study evaluated the effect of two commercial silage inoculants on fermentation, dry matter loss, aerobic stability and the level of hydrocyanic acid of whole-plant sorghum. Sorghum [Sorghum bicolor (L.) Moench] variety Vilom ene was harvested at the soft dough maturity stage at 29.8 % DM. Ten mini-silos (1.5 l volume) for each treatment were filled with crop (193 kg DM/m3). Control forage (CON) was not inoculated. AS treatment was inoculated with SiloSolve AS (150,000 total CFU/g of forage), containing Lentilactobacillus buchneri (DSM22501), Lactiplantibacillus plantarum (DSM26571) and Enterococcus faecium (DSM22502). FC treatment was inoculated with SiloSolve FC (150,000 total CFU/g of forage), containing Lentilactobacillus buchneri (DSM22501) and Lactococcus lactis (DSM11037). After 60 d of fermentation at room temperature, five mini-silos per treatment were opened and sampled for proximate analysis, forage hygiene, and the fermentation profile. The content from the other five mini-silos was subjected to an aerobic stability test. Aerobic stability was defined as the time (hours) for the silage temperature to exceed 3.0°C above the ambient temperature. The data were analyzed as a completely randomized design using GLM of Minitab with treatments as a fixed effect. No significant effect of treatments was observed on dry matter loss. Both inoculants increased acetic acid levels in the silages compared with CON; P < 0.05), where FC showed a significantly greater level than AS (3.1, 2.5 and 1.7 % DM for FC, AS, and CON, respectively; Table 1). Both inoculants produced 1,2-propanediol (P < 0.05). FC silage had a greater level of 1,2-propanediol than AS (1.0, 0.4 and 0.0 % DM for FC, AS, and CON, respectively). The concentrations of lactic acid, ammonia-N and ethanol were not different between treatments. FC significantly reduced the count of yeasts (3.1, 4.1, and 4.3 Log10 CFU/g for FC, AS, and CON, respectively). The count of molds was below the detection level (< 2.0 Log10 CFU/g) in all silages. The FC silage markedly improved aerobic stability, extending it to 231 h, compared with 112 and 80 h for the AS and CON treatments (P < 0.001). AS tended to improve aerobic stability compared with CON (P = 0.08). No differences were observed in the concentration of the hydrocyanic acid between treatments. The ensiling process significantly reduced (P < 0.0001) the hydrocyanic acid from 86.4 mg/kg DM in the fresh crop to 58.4 mg/kg DM in silages. Such silage should be fed only together with HCN-free ingredients in a TMR. However, these results demonstrate that only the combination of L. buchneri (DSM22501) and Lactococcus lactis (DSM11037) effectively decreased the yeast count and consequently improved aerobic stability in wholeplant sorghum silage. [ABSTRACT FROM AUTHOR]

Abstract: The aim of this study was to apply near-infrared spectroscopy (NIRS), available biogas plant data and lumped degradation kinetics to predict biogas production (BPr) of maize silage. A full-scale agricultural biogas plant was equipped with NIRS-metrology at the feeding station. Continuously NIR-spectra were collected for 520d. Substrate samples were analyzed by means of feedstuff analysis. Biogas potential of the samples was calculated from the laboratory analysis results and for a sample-subset practically assessed by “Hohenheim biogas tests”. NIRS-regression-models for all mentioned parameters were calibrated. Continuously gathered spectra, NIRS-models, actual plant-feeding data and degradation kinetics were used to calculate time-series of theoretically expectable BPr. Results were validated against measured gas quantity. Determination coefficients between calculated and measured BPr were up to 58.2%. This outcome was mainly due to the positive correlation between BPr and input amount since the substrate was very homogeneous. The use of NIRS seems more promising for plants with stronger substrate heterogeneity. [Copyright &y& Elsevier]

Highlights: [•] N-leaching risk evaluated after biogas residue application to maize and grass. [•] Biogas residue showed similar nitrate-leaching potential as animal slurry. [•] Methane hectare yield, but also nitrate-N loss, was higher for maize than grass. [•] Lower eco-efficiency of maize, i.e. higher nitrate-N loss per unit methane produced. [ABSTRACT FROM AUTHOR]

Abstract: The promotion of electricity generation from renewable energy sources has led to a substantial expansion of biogas production in Germany, with most biogas plants co-digesting slurry and crops, and maize being by far the most dominant substrate. At present only limited information is available on the agronomic and environmental performance of biogas cropping systems, and on the fertilizer value of biogas residues. In a two-year field experiment at two sites in northern Germany differing in soil quality, we analyzed the dry matter (DM) yield, N yield, methane yield, and the N balance of different cropping systems: (i) maize monoculture (R1), (ii) maize–whole crop wheat followed by Italian ryegrass as a double crop (R2), (iii) maize–grain wheat followed by mustard as a catch crop (R3), and (iv) perennial ryegrass ley (R4). Rotations R1, R2 and R3 were grown at Site 1 (sandy loam), whereas R1 and R4 were tested at Site 2 (humus sand). Crops were supplied with varying amounts (0–360kgNha−1, ryegrass: 0–480kgNha−1) of biogas residue, cattle slurry, pig slurry, or mineral N fertilizer, which allowed quantifying their N use efficiency in terms of apparent N recovery (ANR) and relative N fertilizer value (RNFV). No significant interactions of crop rotation and fertilizer type on DM and methane yield, plant N recovery, as well as N balance, were detected at Site 1, where R1 (19.3tDMha−1; 6750m3 N CH4 ha−1; N: norm conditions, i.e. 273K, 1024hPa) clearly out-yielded R2 (16.8tDMha−1; 5351m3 N CH4 ha−1) and R3 (12.8tDMha−1), while R2 had a higher plant N recovery. At Site 2, the perennial ryegrass ley achieved substantially lower maximum DM and methane yield (13.9tDMha−1; 4251m3 N CH4 ha−1) than maize monoculture (17.3tDMha−1; 6038m3 N CH4 ha−1). Fertilizer type affected grass performance: application of biogas residue resulted in lower yield and N recovery, but higher N balance than mineral fertilizer and cattle slurry. The N use efficiency of biogas residue application depended on the crop rotation. Biogas residue resulted in higher ANR and RNFV compared to pig slurry in R1, whilst in R2 the reverse occurred, and effects were similar to cattle slurry in R4. The results revealed that, except for grassland, substrate cropping based on biogas residues can exploit the yield potential without causing high N surplus. [Copyright &y& Elsevier]