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The concept of a green biorefinery has recently gained interest and can be defined as a process where green biomass is processed to a variety of products. Most green biorefineries rely on fresh green biomass as the feedstock, but using a stable ensiled biomass could provide benefits. We evaluated the effects of silage additive treatments on silage fermentation quality and performance in a laboratory scale liquid–solid separation to simulate the first step of a green biorefinery. In Experiment 1, red clover and fresh and wilted grass were ensiled without additive or treated with a lactic acid bacteria inoculant or a formic acid based additive. In Experiment 2, grass or red clover were treated with a fibrolytic enzyme, formic acid or a combination of them, and a control without additive was also included. Silage fermentation quality was improved by additive use. Biomass dry matter concentration was negatively related to liquid yield, but effects of additive treatments on the biorefinery performance were minor and inconsistent between different forages. Optimizing agronomic and feedstock conservation management plays an important role for the success and sustainability of the biorefinery process. Good silage management practices with minimal losses during storage should be targeted, but no clear patterns in biorefinery outputs were observed in the current study when different types of additives were used in grass and clover silage production. [ABSTRACT FROM AUTHOR]

Abstract: Highlights of progress in the production of silage over the past 50 years include the introduction of improved hybrids of maize (Zea mays L.), the forage harvester, the big baler, polyethylene covering for horizontal silos, stretch‐wrap film for bales and novel additives designed to improve the fermentation and aerobic stability of silage. The key biochemical pathways in the silage fermentation have been described together with the effects of microbial and chemical additives on fermentation and aerobic stability during the feed‐out phase. The significance of oxygen and water in silage fermentation has been quantified and efficacy of covering silos has been established, with recent progress in the development of oxygen barrier film. Future perspectives include improving food safety and animal health by increasing the hygienic quality of silage, reducing the environmental impact of silage by decreasing loss of nitrogen to soil and atmosphere, reducing methanogenesis in the rumen and increasing methane yield from silage as biofuel, and the use of silages as feedstocks for multiple end uses in biorefineries. [ABSTRACT FROM AUTHOR]

Mown herbage of timothy-meadow fescue (dry matter 218 ( LDM) or 539 ( HDM) g kg−1) was ensiled in laboratory silos to evaluate silage additives. For LDM silage, additives including formic acid (a blend of formic acid, sodium formate, propionic acid, benzoic acid, glycerol and another blend of formic acid and ammonium formate, both applied at 5 L t−1) were able to restrict fermentation and thereby improve intake potential of the silage. Aerobic stability ( AS) of total mixed ration ( TMR) was also improved. LDM grass treated with homofermentative lactic acid bacteria (ho LAB) resulted in silage containing lactic acid at 132 g kg−1 DM, ammonium-N <40 g kg−1 total N, and pH < 3·8, and the AS was poor (<36 h). The treatment including heterofermentative strain ( Lactobacillus brevis) produced more acetic acid and better AS than ho LAB. Salt treatment (sodium benzoate, potassium sorbate, sodium nitrite) reduced pH compared to the Control treatment (3·89 vs. 4·24) and improved AS of TMR. The LDM Control silage had good AS, but the TMR based on it had poor AS. All additives were able to lower pH on HDM silages also, but other benefits of using additives were minimal. The treatment including L. brevis on HDM was able to improve AS of TMR. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate the effect of correcting indigestible neutral detergent fibre (i NDF) for the loss of lignin in predictions of silage organic matter digestibility ( OMD). Twenty-five primary and regrowth grass and red clover silages with known in vivo OMD in sheep were used. Silage and faecal samples were analysed by different lignin assays: the Klason method, acid detergent lignin ( ADL) and permanganate lignin. The methods were evaluated by the Lucas test. The slopes in Lucas fits of primary and regrowth grass and red clover silages did not differ, and faecal recovery of ADL was not different from unity. The i NDF was recovered from 288-h in situ incubations in three dairy cows and analysed for ADL. Recovery of ADL in i NDF was 0·562 and 0·801 for grass and red clover silages. Silage concentration of i NDF performed better compared to the different lignin fractions in predicting OMD. Correcting individual samples for loss of ADL as well as using a general correction based on the Lucas fits of ADL in i NDF of grass and red clover silages lowered the prediction error of OMD, but despite losses of ADL in i NDF, the improvements in predictions of OMD were marginal. [ABSTRACT FROM AUTHOR]

The potential of different laboratory methods to predict legume silage organic matter digestibility (OMD) in vivo was evaluated by using data from thirty-three pure legume silages in seven experiments. The samples were analysed for crude protein concentration, cell wall composition, in vitro digestibility by the methods of Tilley and Terry [ Journal of the British Grassland Society, 18 (1963) , 104–111; OMDT&T], pepsin-cellulase solubility (OMS) and gas production (OMDGAS), and for indigestible neutral-detergent fibre concentration in situ (INDF). The relationships between the results obtained by the laboratory methods and in vivo OMD, all expressed as ratios, were studied using linear univariate regression models with experiment as a random variable (mixed model). Legume silage digestibility could be estimated with acceptable accuracy by different in vitro methods, but not from the chemical composition of the samples. The highest accuracy in OMD prediction was found with OMS (RMSE 0·0113; R2 = 0·965) followed by OMDGAS (RMSE 0·0149; R2 = 0·944), OMDT& T (RMSE 0·0149; R2 = 0·940) and INDF (RMSE 0·0168; R2 = 0·925). The relationships between the in vitro methods and in vivo digestibility are not universal, and should be determined separately for each laboratory and type of forage. Part of the error in OMD prediction can be attributed to errors in in vivo OMD determination. [ABSTRACT FROM AUTHOR]