Higher Volatile Fatty Acids Research Articles

Co-hydrothermal carbonisation of sewage sludge and kitchen waste: Influence of process parameters

This study assessed the impact of process temperature and time on the co-hydrothermal carbonisation (co-HTC) of kitchen waste and sewage sludge. To address the limitations of using a single feedstock and to circumvent the energy costs associated with pre-drying, the two organic feedstocks were mixed at a 1:1 ratio (wet basis). Co-HTC experimental runs were conducted in the temperature range of 180 °C–260 °C for 1, 3, and 5h durations. Co-HTC for sewage sludge and kitchen waste (1:1 ratio) at 260 °C temperature for 3h duration demonstrated optimal energy enrichment with a maximum energy and carbon densification of 1.50 and 1.47, respectively. The thermogravimetric analysis (TGA) revealed that the hydrochar (HC) produced at 260 °C temperature for 3h duration underwent multistage decomposition with stable intermediates due to the formation of more stable aromatic structures and a heat energy of 21.29 kJ g−1 at 292.87 °C. At the optimal reaction conditions, the process water (PW) exhibited a high volatile fatty acids (VFA) and total kjeldahl nitrogen (TKN) concentration of 1420 mg L−1 and 431.2 mg L−1, indicating its potential for simultaneous energy recovery through anaerobic digestion and nutrient recovery.

Enhancement of volatile fatty acids to extremely high content in fermentation of food waste: Optimization of conditions, microbial functional genes, and mechanisms

The engineering application of volatile fatty acids (VFA) production from food waste (FW) can significantly enhance resource utilization. Enhancing VFA production is crucial for advancing this engineering application. This study presented a economically-feasible method to achieve high VFA production from FW: Conducting fermentation at pH 9 and 37 ℃ with addition of 20 % anaerobic sludge significantly increased the conversion of FW to VFAs (80.56 g COD/L, accounting for 87.37 % of the soluble chemical oxygen demand), while also increasing the content of NH4+-N (2658.15 mg/L). Macrotranscriptomic sequencing showed that Anaerosalibacter, Amphibacillus, Wansuia, Clostridiisalibacter, unclassified Tissierellia, Massilibacterium, unclassified Bacteroidales, and Tissierellia were the key active microorganisms for VFA production. The expression abundance of functional enzymes and genes related to VFA production pathways increased during the fermentation. This study significantly advanced the practical application of VFA production from FW, offering both theoretical insights and bacterial resources.

Impact of thermal hydrolysis on VFA-based carbon source production from fermentation of sludge and digestate for denitrification: experimentation and upscaling implications

Stricter nutrient discharge limits at wastewater treatment plants (WWTPs) are increasing the demand for external carbon sources for denitrification, especially at cold temperatures. Production of carbon sources at WWTP by fermentation of sewage sludge often results in low yields of soluble carbon and volatile fatty acids (VFA) and high biogas losses, limiting its feasibility for full-scale application. This study investigated the overall impact of thermal hydrolysis pre-treatment (THP) on the production of VFA for denitrification through the fermentation of municipal sludge and digestate. Fermentation products and yields, denitrification efficiency and potential impacts on methane yield in the downstream process after carbon source separation were evaluated. Fermentation of THP substrates resulted in 37–70 % higher soluble chemical oxygen demand (sCOD) concentrations than fermentation of untreated substrates but did not significantly affect VFA yield after fermentation. Nevertheless, THP had a positive impact on the denitrification rates and on the methane yields of the residual solid fraction in all experiments. Among the different carbon sources tested, the one produced from the fermentation of THP-digestate showed an overall better potential as a carbon source than other substrates (e.g. sludge). It obtained a relatively high carbon solubilisation degree (39 %) and higher concentrations of sCOD (19 g sCOD/L) and VFA (9.8 g VFACOD/L), which resulted in a higher denitrification rate (8.77 mg NOx-N/g VSS∙h). After the separation of the carbon source, the solid phase from this sample produced a methane yield of 101 mL CH4/g VS. Furthermore, fermentation of a 50:50 mixture of THP-substrate and raw sludge produced also resulted in a high VFA yield (283 g VFACOD/kg VSin) and denitrification rate of 8.74 mg NOx-N/g VSS∙h, indicating a potential for reduced treatment volumes. Calculations based on a full-scale WWTP (Käppala, Stockholm) demonstrated that the carbon sources produced could replace fossil-based methanol and meet the nitrogen effluent limit (6 mg/L) despite their ammonium content. Fermentation of 50–63 % of the available sludge at Käppala WWTP in 2028 could produce enough carbon source to replace methanol, with only an 8–20 % reduction in methane production, depending on the production process. Additionally, digestate production would be sufficient to generate 81 % of the required carbon source while also increasing methane production by 5 % if a portion of the solid residues were recirculated to the digester.

In vitro evaluation of ruminal digestibility and fermentation characteristics of local feedstuff-based beef cattle ration

Background: Optimum productivity of beef cattle is achieved with adequate feed supply, both in quality and quantity. Consumption of local feedstuff Neptunia plena L. Benth and Leersia hexandra Swartz as a ration by the animal subject is expected to promote cost efficiency and production, as well as provide essential nutrition needs. Therefore, this research aimed to evaluate dry matter digestibility (DMD), organic matter digestibility (OMD), N-NH3 production, and volatile fatty acid (VFA) in beef cattle. Methods: Feed and rumen inoculum samples were prepared and analyzed for their proximate contents. There were five treatment groups based on the diet received by beef cattle. In vitro approaches were used to determine the DMD, OMD, N-NH3 production, and VFA in beef cattle. The research was conducted in the Laboratory of Feed Nutrient Science, Faculty of Animal Husbandry and Agriculture, Diponegoro University, Semarang. The data were analyzed using ANOVA at a significance level of 95%, and a Duncan Multiple Range Test. Results: The results showed that the highest DMD (P<0.05) was derived from T5 (56.47%), followed by T4 (56.45%) and T3 (55.90%). T5=62.40% significantly (P<0.05) generated the highest OMD followed by T4=61.95% and T3=60.82%. This treatment had the highest N-NH3 value, namely 5.02 mM, compared with T3=4.55 mM, T4=4.50 mM, T2=4.22 mM, and T1=3.99 mM. Furthermore, T5 had the highest VFA (P<0.05) compared with T4, T3, T2, and T1 with the value of 150.5, 133.0, 130.5, 130.0, and 123.5 mM, respectively. Conclusions: The local feedstuff-based ration contributed to beef cattle production.

Methacrylonitrile‐based adsorbents for recovery of VFAs from fermentation broth

AbstractBACKGROUNDAdsorption is a promising affinity separation technique to target a sorbate in extremely dilute solutions. In this work, methacrylonitrile (MAN)‐functionalized resins were investigated to recover volatile fatty acids (VFAs) from a mimicked fermentation broth as an alternative for the already known amine‐based resins and non‐functionalized poly(styrene‐divinylbenzene) (PS‐DVB), aiming for high VFA capacity and selectivity.RESULTSNext to comparison with commercial PS‐DVB resin, also several PS‐DVB resins were synthesized as non‐functionalized analogues for the new MAN‐functionalized resins. For MAN‐functionalized resins, the maximum equilibrium VFA loading of about 153 (g acid/kg adsorbent) was found, which is higher than the 125 (g acid/kg adsorbent) for the PS‐DVB non‐functionalized resins. The water uptake of the PS‐DVB resins was with 0.53–0.87 (g water/g adsorbent) significantly lower than for the MAN‐DVB resins taking up 0.99–1.85 (g water/g adsorbent).CONCLUSIONOverall, the MAN‐functionalized adsorbents retained higher loading capacity for corresponding acid, compared to the PS‐DVB resins, while also taking in more water. Acid uptake is due to the hydrogen bonding between the nitrile groups of the resins with carboxyl group of the acids. Moreover, none of the adsorbents displayed an affinity towards the salts present in the fermentation broth. © 2024 The Author(s). Journal of Chemical Technology and Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry (SCI).

Feeding Astragalus membranaceus Root Improves the Rumen Fermentation Rate in Housed Goats through the Alteration of the Rumen Community Composition.

Although Astragalus membranaceus root (AMR) has been noted as an ingredient in ruminant feed, the impacts of AMR feeding on rumen fermentation and the microbial community structure within the rumen are yet to be evaluated. This study investigated the effects of AMR supplementation on rumen fermentation characteristics and microbial community structures in goats. In two sets of feeding experiments, four Japanese native goats were fed AMR (10 g/kg DM/day/head) for three weeks per experiment. The rumen fluid samples were analyzed using high-performance liquid chromatography for fermentation products and next-generation sequencing for microbial analysis. The rumen fluid samples in the second experiment were also subject to an in vitro anaerobic fermentation test. The results indicated a significant modification, with a higher volatile fatty acid (VFA) content in the rumen fluid of goats in the feeding period than before feeding (p < 0.01). The microbial analysis revealed a significant increase in community diversity (p < 0.05) following AMR feeding, and the rumen bacterial community increased in two families belonging to the order Oscillospirales in Firmicutes (p < 0.05). The phylum Verrucomicrobiota was observed to be significantly less abundant after AMR feeding than during the control period (p < 0.05). Notably, the linear discriminant analysis revealed that the families with largely unknown functions in the rumen (Oscillospiraceae, Rikenellaceae, Muribaculaceae, and vadinBB97) were the determinants of the community split between control and AMR feeding. Increased fermentation rate by AMR feeding was also supported by an in vitro culture experiment, which resulted in faster VFA production without affecting methane production in total gas production. The study demonstrated that AMR can significantly facilitate change in the bacterial community structure in the goat rumen involving a shift of the favoring fibrolytic bacteria towards VFA production. The long-term effects of AMR supplementation and its applicability across different ruminant species, with potential benefits for animal health and productivity, should be addressed.

Source-Separated Industrial Wastewater Is a Candidate for Biogas Production through Anaerobic Digestion

Anaerobic digestion is a potential treatment for industrial wastewater that provides valuable end-products, including renewable energy (biogas). However, waste streams may be too variable, too dilute at high volumes, or missing key components for stable digestion; all factors that increase costs and operational difficulty, making optimisation crucial. Anaerobic digestion may benefit from process intensification, particularly the novel combination of high-strength source-separated wastewater to minimise volume, together with the use of biosolids biochar as a chemical and microbial stabiliser. This study investigates the stability, yield, and microbial community dynamics of the anaerobic digestion of source-separated industrial wastewater from a food manufacturer and a logistics company, using biosolids biochar as an additive, focusing on gas and volatile fatty acid (VFA) production, process stability, and the microbial community using bench-scale semi-continuous reactors at 30- and 45-day hydraulic retention time (HRT). While gas yields were lower than expected, stability was possible at high HRT. Methane production reached 0.24 and 0.43 L day−1 per litre reactor working volume at 30- and 45-day HRT, respectively, despite high VFA concentration, and was linked to the relative abundance of Methanosarcina in the microbial community. Interactions between substrate, VFA concentration, and the microbial community were observed. Biochar-assisted anaerobic digestion holds promise for the treatment of source-separated wastewater.

Volatile fatty acids production from kitchen waste slurry using anaerobic membrane bioreactor via alkaline fermentation with high salinity: Evaluation on process performance and microbial succession

In this study, a pilot-scale anaerobic membrane bioreactor (AnMBR) was developed to continuously produce volatile fatty acids (VFAs) from kitchen waste slurry under an alkaline condition. The alkaline fermentation effectively suppressed methanogenesis, thus achieving high VFAs production of 60.3 g/L. Acetic acid, propionic acid, and butyric acid accounted for over 95.0 % of the total VFAs. The VFAs yield, productivity, and chemical oxygen demand (COD) recovery efficiency reached 0.5 g/g-CODinfluent, 6.0 kg/m3/d, and 62.8 %, respectively. Moreover, the CODVFAs/CODeffluent ratio exceeded 96.0 %, and the CODVFAs/NH3-N ratio through ammonia distillation reached up to 192.5. The microbial community was reshaped during the alkaline fermentation with increasing salinity. The membrane fouling of the AnMBR was alleviated by chemical cleaning and sludge discharge, and membrane modules displayed a sustained filtration performance. In conclusion, this study demonstrated that high-quality VFAs could be efficiently produced from kitchen waste slurry using an AnMBR process via alkaline fermentation.

Peroxydisulfate activation and versatility of defective Fe3O4@MOF-808 for enhanced carbon and phosphorus recovery from sludge anaerobic fermentation

Although being viewed as a promising technology for reclamation of carbon and phosphorus from excess sludge, anaerobic fermentation (AF) grapples with issues such as a low yield of volatile fatty acids (VFAs) and high phosphorus recovery costs. In this study, we synthesized Fe3O4@MOF-808 (FeM) with abundant defects and employed it to simultaneously enhance VFAs and phosphorus recovery during sludge anaerobic fermentation. Through pre-oxidization of sludge catalyzed by FeM-induced peroxydisulfate, the soluble organic matter increased by 2.54 times, thus providing ample substrate for VFAs production. Subsequent AF revealed a remarkable 732.73 % increase in VFAs and a 1592.95 % increase in phosphate. Factors contributing to the high VFAs yield include the non-biological catalysis of unsaturated Zr active sites in defective FeM, enhancing protein hydrolysis, and the inhibition of methanogenesis due to electron competition arising from the transformation between Fe(III) and Fe(II) under Zr influence. Remarkably, FeM exhibited an adsorption capacity of up to 92.64 % for dissolved phosphate through ligand exchange and electrostatic attractions. Furthermore, FeM demonstrated magnetic separation capability from the fermentation broth, coupled with excellent stability and reusability in both catalysis and adsorption processes.

Acidogenic fermentation of biowaste coupled with nitrogen recovery using selective membranes to produce a VFA-rich liquid with a high C/N ratio

This research focuses on the production of a liquid stream rich in volatile fatty acids (VFAs) and low ammoniacal nitrogen content (<0.1 g N/L) from biowaste. The liquid stream was obtained by combining (i) mixed culture acidogenic fermentation to maximise VFA production and (ii) gas-permeable membrane (GPM) contactor to recover ammoniacal nitrogen. Three batch fermentation tests of biowaste collected in a full-scale mechanical-biological treatment plant provided high and stable VFA concentrations (37–39 g CODVFA/L). VFAs represented 73–81 % of the soluble chemical oxygen demand (sCOD) concentration, with a predominance of acetic, propionic and butyric acids. A highly specialized microbial community was observed in all batch tests, with Bacteroidota and Firmicutes as predominant phyla (>90 % of relative abundance). The GPM contactor recovered more than 99 % of the ammoniacal nitrogen in the fermentation liquid without VFA losses. The suitability of the produced fermentation liquid with a high C/N ratio for downstream applications was evaluated using biomethane potential tests (BMP) at different total ammonium nitrogen (TAN) concentrations (0.76–3.15 g N/L) and circumneutral pH. Despite achieving similar ultimate methane yields (279–314 NmL CH4/g CODfeed), lower TAN concentrations in the biowaste fermentation liquid improved anaerobic biodegradation kinetics, enhancing its potential applicability for methane production.

Microbial composition play the leading role in volatile fatty acid production in the fermentation of different scale of corn stover with rumen fluid.

Rumen fluid is a natural and green biocatalyst that can efficiently degrade biomass into volatile fatty acid (VFA) used to produce value-added materials. But the essence of high degradation efficiency in the rumen has not been fully analyzed. This study investigated the contribution of substrate structure and microbial composition to volatile fatty acid production in the fermentation of corn stover. The ball milled corn stover were innovatively applied to ferment with the rumen fluid collected at different digestion times. Exogeneous cellulase was also added to the ruminal fermentation to further reveal the inner mechanism. With prolonged digestion time, the microbial community relative abundance levels of Bacteroidetes and Firmicutes increased from 29.98% to 72.74% and decreased from 51.76% to 22.11%, respectively. The highest VFA production of the corn stover was achieved via treatment with the rumen fluid collected at 24h which was up to 9508mg/L. The ball milled corn stover achieved high VFA production because of the more accessible substrate structure. The application of exogenous cellulase has no significant influence to the ruminal fermentation. The microbial community abundance contributed more to the VFA production compared with the substrate structures.

Generation of High Concentration Free Volatile Fatty Acids from Continuous Anaerobic Digestion of Chicken Manure by Suppressing the Decomposition of Nitrogenous Components.

Free volatile fatty acids (free VFA) play a crucial role in the inactivation of pathogens during the anaerobic digestion of animal manure. However, the decomposition of nitrogenous components can release alkaline ammonium-N, which might increase the pH and reduce the concentration of free VFA. In this study, continuous anaerobic digestion of high-solid chicken manure was conducted for 150days. The results indicated the process stabilized at a pH of approximately 6.0, with total ammonia nitrogen (TAN) of around 7.0g/L. The resulting concentration of free VFA was only about 3.1g/L, which might not sufficiently effective for pathogen inactivation. On the 70th day, hydrogen chloride was added into the reactor to adjust the pH to 5.5. This led to a further decrease in pH to 4.3 and TAN to 2.3g/L. As a result, the concentration of free VFA significantly increased, reaching up to 12.6g/L. These findings support the potential for generating high levels of free VFA even for nitrogen-rich manure by implementing an appropriate process regulation.

Marine Macroalgae in Rabbit Nutrition: In Vitro Digestibility, Caecal Fermentability, and Microbial Inhibitory Activity of Seven Macroalgae Species from Galicia (NW Spain)

The limitation on the prophylactic use of antibiotics in animal feed in Europe has critically challenged the rabbit meat industry, which urgently needs to find solutions. A feasible alternative could be using macroalgae in the diet to improve the gut health. This research studied seven species of marine macroalgae in four formats (dehydrated, enzymatically hydrolyzed, aqueous extract, and aqueous extract of hydrolyzed macroalgae) in order to select the most promising ones for their use in rabbit feed. Chemical composition, in vitro digestibility, in vitro caecal gas, total volatile fatty acid (VFA) production, and minimal inhibitory concentrations (MIC) against common pathogens were studied. All S. latissima products showed high caecal fermentability and VFA production, especially in both types of extracts. The H. elongata aqueous extract was remarkable due to its high in vitro butyrate production, which can be of great interest for improving gut health. The MIC results did not indicate any clear inhibition of the pathogens tested. The macroalgae tested appear to have a potentially prebiotic effect, rather than a direct antimicrobial activity. However, these results must be confirmed in vivo, in order to observe the real benefits of feeding macroalgae during the rabbit weaning period.

Performance and mechanisms of urea exposure for enhancement of biotransformation of sewage sludge into volatile fatty acids

Herein, a cost-effective method for improving the anaerobic fermentation performance of sewage sludge (SS) is proposed. The highest volatile fatty acids (VFAs) reached up to 5550 mg COD/L with the supplementation of 0.2 g urea/g total suspended solids (TSS). Intensive exploration showed that SS decomposition was profoundly triggered by urea and the free ammonia generated due to the hydrolysis of urea, providing adequately bioaccessible substrates for acidogenic reactions and thus contributing to VFAs formation. Microbial composition analysis indicated that functional bacteria (i.e., Tissierella and Clostridium) associated with VFAs generation were enriched. Moreover, the metabolic activities of functional flora (i.e., membrane transport and fatty acid synthesis) were up-regulated due to the stimulation of urea. In general, the increase in bioavailable organic matter and functional microbes, and thus the increased microbial metabolic activities, improved the efficient production of VFAs. This study could provide a cost-effective approach for resource recovery from SS.

Evaluating optimized volatile fatty acids production from carbon-rich wastewater during hydrolysis acidification process by Fe(Ⅱ) and Fe(Ⅲ) addition

Volatile fatty acids (VFAs), a value product of hydrolysis acidification (HA) has been grasped ample eyeballs. Fe(Ⅱ) and Fe(Ⅲ) were applied to enhance VFAs production from carbon-rich starch wastewater in this investigation. VFAs productivity was improved 6.5–15.2% than the control system when Fe(Ⅱ) and Fe(Ⅲ) were supplemented. The enrichment of key functional HA microbes identified by molecular ecological network analysis (MENA) and improved key enzymes’ activity contributed to promotion of organics hydrolysis, triggering high VFAs yields. After further analysis, it was clarified that the microbial metabolism's influence on pH and the presence of Fe2+ in the systems were key factors contributing to the improvement of the microbial community structure and the activity of key enzymes, respectively. Detailed comparison analysis was also conducted between RFe(Ⅱ) and RFe(Ⅲ) systems. Totally, from the perspective of performance and environmental, Fe(Ⅱ) and Fe(Ⅲ) have great engineering application potential on enhancing VFAs production, especially for Fe(Ⅱ).

Alkaline-thermal and mild ultrasonic pretreatments for improving biomethane yields: Impact on structural properties of chestnut shells

The high fiber content of chestnut shells (CS) makes biomethane production inefficient when using the anaerobic digestion (AD) method. Therefore, this study has evaluated for the first time the combined effect of alkaline-thermal (AT) and mild ultrasonic (US) pretreatments prior to the AD of CS. The cumulative biomethane yields (CMY) of untreated and pretreated (4% NaOH + 100 °C thermal + US) CS were 79.10 ± 7.9 and 266.9 ± 9.3 mL CH4/g VS, respectively. The effects of the pretreatment of lignocellulosic biomass at different intensities were interpreted according to amounts of lignocellulosic solubilization, soluble chemical oxygen demand/total chemical oxygen demand, and scanning electron microscope images. Solubilization of the lignin from CS with pretreatments varied between 44.5 and 65.6% w/w. The use of AT pretreatments, together with US pretreatments, successfully increased the solubility of lignocellulosic compounds compared to the first case, whilst CMYs showed a positive correlation with lignocellulosic solubilization amounts. After pretreatments, total volatile fatty acid (VFA) concentrations were measured in the anaerobic process, from which the highest VFA was measured to be 1555 ± 108 mg HAc L-1, well below the appropriate value for AD (≤8000 mg HAc L-1). After pretreatments, the CMYs were successfully simulated by the modified Gompertz and Logistic model (R2 = 0.942–0.984). This study presents a promising strategy in the sense that the biomethane yield of CS containing large amounts of fiber can be significantly increased by combined AT and mild US pretreatment methods.

Co-digestion of mushroom compost with switchgrass using solid-state anaerobic digester

Spent mushroom compost (SMC) already broken down into smaller particles by fungal action is an ideal material for producing biogas. Two cycles of five solid-state anaerobic digesters (SS-ADs) with different mix-ratio of SMC and switchgrass (SG) were operated at feedstock-to-effluent ratio of 2 at a temperature 35 ± 2°C. The total solids concentration of the digester was kept at ∼17%. Initial biogas production observed during the start-up of the digester confirmed the presence of readily available extractives for digestion. In the first cycle, the highest methane yield was observed in SMC 0 (0% SMC + 100% SG) of 28.82 l/kg VS/d and the lowest yield was observed in SMC 4 (100% SMC + 0% SG) as 10.32 l/kg VS/d. The substrate containing 100% SG (SMC 0) recorded the highest cumulative biogas yield of 295.43 l/kg VS in 63 days. The digesters with higher SMC fraction showed lower methane production, low pH value and high volatile fatty acids content upon decomposition. The SS-ADs having SMC/SG of 50 : 50 showed more than 2 times methane production in comparison with SS-ADs having SMC as sole substrate. An estimation of volumetric productivity also established a linear relationship with the SMC/SG ratio.

Feed intake and milk yield and composition of lactating dairy goats in response to partial substitution of soybean meal for formaldehyde-treated sesame meal in the diet

ABSTRACT This study was conducted to evaluate the effect of substitution of soybean meal (SBM) for formaldehyde-treated sesame meal (FTSM) on nutrient intake and digestibility, ruminal and blood parameters and milk production and composition in lactating Murciano-Granadina goats. Forty lactating goats were randomly assigned to one of the following four treatments: (1) diet with 16.5% CP, containing SBM (CON); (2) diet with 16.5% CP, containing untreated SM (USM); (3) diet with 16.5% CP, containing FTSM (FT); and (4) diet with 14.5% CP containing FTSM (LPFT). The results showed that nutrient intake was highest in the FT group (p < 0.001), while it was similar between the CON and LPFT groups, except for the intake of CP, which was higher in the CON group. The FT and LPFT had lower ruminal pH compared to CON and USM groups (p < 0.001), with goats in group FT having the highest volatile fatty acids (VFA) production (p < 0.001). The highest propionate concentration was observed in the LPFT treatment (p < 0.001), followed by the FT, CON, and USM treatments. Goats offered USM and LPFT treatments presented the highest and lowest acetate: propionate values, respectively, among the experimental groups (p < 0.001). The results also showed that LPFT goats had the lowest blood urea nitrogen (BUN) level (p = 0.004), while FT goats presented a lower non-esterified FA (NEFA) level compared with CON and LPFT goats (p = 0.01). Goats offered the FT diet had the highest milk yield (p = 0.002) and energy-corrected milk yield (p < 0.001) among all dietary groups. The highest milk fat (p < 0.001), protein (p = 0.001), lactose (p = 0.007), total solids (p = 0.003), and solids-not-fat (SNF) (p = 0.003) contents were observed in FT goats, which didn’t differ from USM goats. The inclusion of formaldehyde-treated SM increased the percentage of C18:3 (p < 0.001) and C20:1 (p = 0.04) FAs compared with USM and CON treatments. Milk from USM, FT, and LPFT goats had lower levels of saturated (p < 0.001) and medium-chain FAs (p = 0.014) compared with CON goats, whereas milk from CON goats had lower levels of unsaturated, monounsaturated, and long-chain FAs compared to other groups (p < 0.001). The lowest and the highest concentrations of polyunsaturated FAs were observed in CON and LPFT goats, respectively (p = 0.001). It can be concluded that SBM can be advantageously replaced by formaldehyde-treated SM in the diet as a feasible alternative to improve feed intake and production performance of dairy goats.

In vitro evaluation of ruminal digestibility and fermentation characteristics of local feedstuff-based beef cattle ration

Background: Consumption of local feedstuff Neptunia plena L. Benth and Leersia hexandra Swartz as a ration by the animal subject is expected to promote cost efficiency and production, as well as provide essential nutrition needs. Therefore, this study aimed to evaluate ruminal dry matter digestibility (DMD), organic matter digestibility (OMD), ammonia (NH 3) production, and volatile fatty acid (VFA) in beef cattle. Methods: Feed and rumen inoculum samples were prepared and analyzed for their proximate contents. There were five treatment groups based on the diet received by beef cattle, namely: T 1 ( Leersia hexandra Swartz 100 %); T 2 ( Neptunia plena L. Benth 100%); T 3 ( Leersia hexandra Swartz 15% + ( Neptunia plena L. Benth 15% + 70 % Other Feedstuffs); T 4 ( Leersia hexandra Swartz 20% + ( Neptunia plena L. Benth 20% + 60% Other Feedstuffs); T 5 ( Leersia hexandra Swartz 25% + ( Neptunia plena L. Benth 25% + 50% Other Feedstuffs). In vitro approaches were used to determine the DMD, OMD, NH 3 production, and VFA in beef cattle. Results: The results showed that the highest DMD (P&lt;0.05) was derived from T 5 (56.47%), followed by T 4 (56.45%) and T 3 (55.90%). T 5=62.40% significantly (P&lt;0.05) generated the highest OMD followed by T 4=61.95% and T 3=60.82%. This treatment had the highest NH 3 value, namely 5.02 mM, compared with T 3=4.55 mM, T 4=4.50 mM, T 2=4.22 mM, and T 1=3.99 mM. Furthermore, T 5 had the highest VFA (P&lt;0.05) compared with T 4, T 3, T 2, and T 1 with the value of 150.5, 133.0, 130.5, 130.0, and 123.5 mM, respectively. Conclusions: The local feedstuff-based ration can be used to ensure the sustainable production of beef cattle

Integrated genome-centric metagenomic and metaproteomic analyses unravel the responses of the microbial community to ammonia stress

Ammonia is a major inhibitor in anaerobic digestion of nitrogen-rich organic wastes. In this study, integrated genome-centric metagenomic and metaproteomic analyses were used to identify the key microorganisms and metabolic links causing instability by characterizing the process performance, microbial community, and metabolic responses of key microorganisms during endogenous ammonia accumulation. The identification of 89 metagenome-assembled genomes and analysis of their abundance profile in different operational phases permitted the identification of key taxa (Firmicutes and Proteobacteria) causing poor performance. Metabolic reconstruction indicated that the key taxa had the genetic potential to participate in the metabolism of C2C5 volatile fatty acids (VFAs). Further investigation suggested that during Phase I, the total ammonia nitrogen (TAN) level was maintained below 2000 mg N/L, and the reactor showed a high methane yield (478.30 ± 33.35 mL/g VS) and low VFAs concentration. When the TAN accumulated to > 2000 mg N/L, acid accumulation, mainly of acetate, began to occur, and the methane yield gradually decreased to 330.44 mL/g VS (Phase II). During this phase, the VFA degradation functions of the community were mainly mediated by Firmicutes. Approximately 61.54% of significant differentially expressed proteins (DEPs) related to acetate metabolism in Firmicutes were down-regulated, which led to an increase in acetate concentration to 4897.91 ± 1558.96 mg/L. However, the reactor performance showed spontaneous recovery without any interference (Phase III), during which Firmicutes gradually adapted to the high ammonia conditions. Approximately 75% of the significant DEPs related to acetate metabolism of Proteobacteria were also up-regulated in Phase III compared with Phase II; thus, VFA-related metabolic functions of the community were enhanced, which resulted in a decrease in the total VFA concentration to 195.39 mg/L. When the TAN increased above 4000 mg N/L, the system gradually showed acid accumulation dominated by propionate, accompanied by a second decrease in methane yield (Phase IV). During this phase, the number of up-regulated and down-regulated proteins related to acetate metabolism of Firmicutes and butyrate/valerate metabolism of Proteobacteria was comparable with that of Phase III, indicating that the metabolic functions related to acetate, butyrate, and valerate of the microbial community were not significantly affected. However, for propionate metabolism, the expression activity of fumarate hydratase from Firmicutes and Proteobacteria was severely inhibited by ammonia, as shown by down-regulation ratios of 63.64% and 85.71%, respectively. No protein with the same function that was not inhibited by ammonia could be detected, and the fumarate degradation function of the microbial community was severely damaged, leading to blocked propionate metabolism and irreversible deterioration of reactor performance. This study has provided a new perspective on the microecological mechanisms of ammonia inhibition.