Dry Digestibility Research Articles

Biokonversi Pelepah Daun Nipah Menggunakan Jamur Tiram Putih Ditinjau Dari Komposisi Kimia dan Kecernaan Serat

The study aims to determine the chemical composition and digestibility of midrib palm leaves from bioconversion results. Solid bioconversion using white oyster mushroom inoculum as a starter. This study used a completely randomized design (RAL) with 6 treatments and 3 replications. As a treatment the white oyster mushroom inoculum consisted of 6 levels, namely 0g (with inoculum), 5g, 10g, 15g, 20g and 25g kg-1 substrate. The variables measured are the chemical composition and digestibility of nipah leaf midrib fiber bioconversion products. The results showed that organic matter content, ADF digestibility and nipah leaf midrib cellulosa bioconversion results were significantly different (P<0.05) but the dry matter content, crude protein and NDF digestibility did not show significant differences (P>0.05) due to the levels of white oyster mushroom inoculum. The best digestibility occurred at the levels of white oyster mushroom inoculum 20g kg-1 substrate with acid digestibility fiber 27,31% and cellulose 31,08%. It can be concluded thah the level of white oyster mushroom inoculum 20g kg-1 substrate for nipah leaf midrib bioconversion results is the best.

Yield and nutritional value of BRS Capiaçu grass at different regrowth ages

The objective was to evaluate the productivity, chemical composition, ruminal degradability of dry matter and digestibility of BRS capiaçu grass (Pennisetum purpureum Schum.) managed at five regrowth ages. A completely randomized design with ten replications was used in the BRS capiaçu elephant grass subjected to five cutting intervals (30, 60, 90, 120 and 150 days) in the summer, making a total of 50 plots with a useful area of 4 x 2 m. There were daily increases in the dry matter production in the order of 382 kg ha-1, with 49,859 kg ha-1 being produced at 150 regrowth days. The dry matter content and organic matter linearly increased (P < 0.01) at different regrowth ages. The crude protein content, in vitro dry matter digestibility and in vitro digestibility of neutral detergent fiber linearly reduced (P < 0.01) 0.037%, 0.196% and 0.256% per day, respectively. Potential degradability of dry matter decreased from 68.9% at 30 days to 44.7% at 150 regrowth days (0.194 percentage units per day). The rate of degradation of fraction B 'c' was not modified (P = 0.94), averaging 1.46% hour-1. In the cultivation of BRS capiaçu elephant grass in the summer season, in the northern region of Minas Gerais, the age for harvesting between 90 and 120 days of regrowth is recommended.

Dry anaerobic co-digestion of roadside grass and cattle manure at a 60 L batch pilot scale

Roadside grass cuttings and solid cattle manure are resources that are available as input for dry anaerobic co-digestion. Two series of measurements were carried out, one in June 2016 and one in October 2016. The methane potentials were determined on a laboratory scale and revealed a high degree of seasonality, 202.9 and 167.9 Nm3CH4.tVS−1, respectively. Moreover, these substrates were co-digested in reactors by the dry process on a pilot scale (60 L). Two strategies for filling and optimization, as layers or as a mixture, were compared. The seasonality also determined the physicochemical parameters and the hydrodynamic properties involved in percolation of the liquid phase recirculated in the dry digestion process. The production of methane depended on the filling method, the seasonality, and the nature of the input, which in some cases resulted in inhibition of 34.8–44.4 Nm3CH4.tVS−1.

EFFECT OF SODIUM HYDROXIDE OR UREA TREATMENT ON CHEMICAL COMPOSITION AND LABORATORY DIGESTION FACTORS FOR BARLEY STRAW AND CORN COBS

These experiments were conducted to study effect of chemical treatment with sodium hydroxide or urea on chemical composition and in vitro digestibility of different roughages such as barley straw and yellow corn cobs. The chemical coefficients were used on the first lap periods of 30 days and 45 days. For determining of the effect of roughages type, the authors observed a high moral superiority (p <0.01) for barley processing in dry matter digesters, organic matter digestion, raw fiber ratio and nitrogen-free extract on feedstocks (P <0.01) for the treatment of sodium hydroxide in the dry digestion factor , organic matter digestion factor, raw fiber ratio, and nitrogen-free extract. When determining the effect of the length factor of the incubation period, the second period (45 days) was significantly higher (p <0.01) in the dry matter digestion coefficient, organic matter digestion factor, raw fiber ratio, crude protein ratio, and nitrogen-free extract compared with the first period. For explaining the effect of the overlap between the type of feed material and the type of chemical treatment, there was significant differences (P <0.01) for barley processing in dry matter digestion, organic matter digestion, crude fiber ratio, and nitrogen-free extract. For determining the effect of overlap between feed type and incubation period type, noted a digest organic matter and nitrogen-free extract and protein on all other transactions.

DIGESTIBILITY ON LOCAL FEMALE RABBIT FED DIETS CONTAINING DIFFERENT LEVELS OF FERMENTED TOFU WASTE

This study aims to determine the digestibility of local female rabbit fed diet containing different levels offermented tofu waste. The study used a randomized block design (RBD), with five treatments and five blocks.The treatment was rabbits fed rations without using tofu waste or control fed (R0), rabbit fed rations containing10% tofu waste (R1), rabbit fed containing 15% tofu waste (R2), rabbit fed rations containing 10% fermented tofuwaste (R3) and rabbit fed rations containing 15% fermented tofu waste (R4). Variables observed were dry matterdigestibility, protein digestibility and efficiency of changes GE to DE. The results showed that rabbits fed ration R3and R4 caused dry matter digestibility, protein digestibility and efficiency of changes GE to DE were higher thantreatments R2, R1 and R0. It can be concluded that diets containing 10% up to 15% fermented tofu waste in rabbitrations can increase the digestibility of rations for local female rabbits.

Soil Fertilization and Texture on Boron Accumulation and Wood Volume in Corymbia citriodora (Hook) K.D. Hill & L.A.S Johnson

This study aimed to evaluate the effects of soil fertilization and texture on leaf Boron (B) accumulation and its relation with wood volume of Corymbia citriodora Hill & Johnson. The experiment was set in randomized block with four replications, four B fertilization levels (0, 1.1, 2.2 and 4.4 g.plant-1) in two soils types (sandy and clayey). To determine leaf B content, 25 leaves were collected from the median portion of four trees for each treatment. Leaves were dried on oven and B content was determined by the Azomethine-H method using extract obtained by dry digestion. The diameter at breast height and the total height of 25 trees were collected in all treatments and wood volume was calculated. Data were submitted to analysis of variance and the means adjusted to regression equations. The regression coefficients were evaluated by t-test at 1 and 5% probability. It was verified that clay soil produces more wood, compared to sandy soil. There was a gain increase in foliar B as B doses increased in both soil types. Leaf B affected Corymbia citriodora productivity only in clay soil.

Dry Anaerobic Digestion of Food and Paper Industry Wastes at Different Solid Contents

A large volume of food is being wasted every year, while the pulp and paper industry also generate a large amount of solid wastes on a daily basis, causing environmental challenges around the world. Dry anaerobic digestion (AD) of these solid wastes is a cost-effective method for proper management. However, dry digestion of these waste streams has been restricted due to their complex structure, the presence of possible inhibitors and inappropriate operating conditions. In light of this fact, dry digestion of food waste (FW) and paper wastes (PW) was conducted at different total solid (TS) concentrations of reactor mixtures of 14%, 16%, 18% and 20% TS, corresponding to substrate to inoculum (S/I) ratio of 0.5 and 1; investigating the optimum operating conditions for effective dry digestion of these complex wastes. The highest methane yields of 402 NmlCH4/gVS and 229 NmlCH4/gVS were obtained from digestion of FW and PW, respectively at 14%TS corresponding to an S/I ratio of 0.5. Increasing the S/I ratio from 0.5 to 1 and thereby having a TS content of 20% in the reactor mixtures was unfavorable to the digestion of both substrates.

Application of Biogas Digestate with Rice Straw Mitigates Nitrate Leaching Potential and Suppresses Root-Knot Nematode (Meloidogyne incognita)

This study investigated the effects of biogas digestate application to soil with rice straw on nitrate leaching potential and nematicidal activity toward root-knot nematodes Meloidogyne incognita. The following seven treatments were set up: (i) control (CONT); (ii) chemical fertilizer (CF); (iii) wet biogas digestate derived from pig manure (WBD); (iv) and (v) dry biogas digestate derived from a mixture of pig manure and rice straw at an initial C/N ratio of 20 and 30 (DBD20 and DBD30); (vi) and (vii) DBD20 mixed with rice straw to adjust the C/N ratio to 16 (Mix1) and 30 (Mix2), respectively. The application rate of CF and digestates was adjusted to 200 mg N kg−1 soil based on the inorganic ammonium nitrogen contents. Nitrate contents readily increased in all the treatments with incubation, except for Mix2, and those at day 90 were decreased with increasing initial labile C contents. Garden balsam was grown as a test plant for root-knot nematodes using the soils at day 90 and the results showed that the gall index was significantly lower in Mix2 and Mix1 than in CF. These results suggest that dry digestate mixed with rice straw might have potential for lower nitrate leaching and nematicidal properties.

Selective silica gel free scandium extraction from Iron-depleted red mud slags by dry digestion

A combination of pyrometallurgical and hydrometallurgical processes showed promising results for the sustainable valorisation of red mud with selective iron recovery. However; high Si content in red mud and its slags produced by pyrometallurgical treatment for the Fe removal makes these secondary resources untreatable with conventional acid leaching routes due to the formation of silica gel. In this study, red mud and slags synthesized by electric arc furnace smelting, which contain both moderate and extensive SiO2, were exposed to dry digestion aiming selective Sc recovery with suppressed Ti and Si dissolution. Various additions of concentrated sulfuric acid were investigated to find out the optimum acid consumption for this process. A promising Sc leaching efficiency was found for acidic slag (~80%), where Ti dissolution was suppressed to <10% and without Si gel formation. The mineralogical content of red mud and the two slags were analysed by QEMSCAN and XRD in order to elucidate the leaching mechanism. Using the findings of this study, an empirical dry digestion leaching model was proposed for each starting material in a comparative manner.

Nutritional Evaluation of Millet Plants Grown in Soils Fertilized With Organic Wastes From Different Sources

The losses of essential elements to crops make necessary to correct soil fertility to meet the nutritional requirements of plants, which can be achieved by increasing soil organic matter. The objective of this work was to evaluate the leaf nutritional conditions of millet plants grown in soils fertilized with organic wastes from different sources at different rates. Organic matter can make the soil more productive and suitable to agricultural crops. A randomized block experimental design with a 4 &amp;times; 2 factorial arrangement was used with four replications, consisting of 32 experimental units. The treatments consisted of four organic matter sources (swine manure, sewage sludge, bovine manure, and poultry litter), and two organic matter rates (20% and 40% of the pot volume). Boron extraction was performed by dry digestion&amp;mdash;the organic matter of the plant tissue was incinerated in an electric muffle furnace at 450-550 &amp;ordm;C, and the inorganic residue (ash) was dissolved in a dilute acid solution. N, K, Ca, Mg, S, Fe, Cu, Mn, and Zn was extracted through wet digestion&amp;mdash;the organic matter of the leaf tissue was oxidized by concentrated mineral acids and by heat. N, P, S, B, Ca, Mg, Cu, Fe, Mn, and Zn was determined by spectrophotometry. K was determined by flame photometry. All macro and micronutrient contents in the millet leaves, and biometric parameters of the millet panicle were affected by the organic matter sources, organic matter rates, and the interaction between them.

Scanning Electron Microscopy and X-ray Diffraction in the Determination of Macroelements in Soil and Plants

ABSTRACTSample preparation is a crucial stage in obtaining correct results for micro- and macro-elements in soil and plants. The current study is a part of systematic research on the methods for soil and plant sample preparation for analysis of the most important macro-elements. The purpose is to determine the limits of the application of the most widely spread standardized and non-standardized methods for sample preparation and to shed more light on the possibilities of using scanning electron microscopy/energy dispersive spectroscopy (SEM-EDS) and X-ray Diffraction (XRD) in soil and plant analysis. The most common methods for extracting macro- elements in soil and plants (dry ashing, acid digestion, and microwave digestion in different variants) were compared using three certified soil samples and the Polish reference material CTR-VTL-2 (Virginia tobacco leaves). Three macro-elements (K, Ca and Mg) in the digest were analyzed using flame AAS and the insoluble fraction after digestion were analysed using XRD and SEM-EDS. It is concluded, that the degree of extraction of the elements from soil and plant materials is highly dependent on the mineralisation method. The X-ray investigation showed the formation of KClO4 when HClO4 was used as a part of the acids mixture. The use of HF at Ca and Mg determination led to the formation of CaF2 and MgF2. The result was verified by SEM-EDS.

SIMULATED SOFC EXHAUSTS AND THEIR FIXATION ON CHLORELLA VULGARIS: STUDY ON AFFECTING PARAMETERS

To curtail greenhouse gas emissions local and distributed energy systems should be fed by renewable and high efficiency fuels. Anaerobic digestate of organic waste from biogas production can be adopted as a substrate, coupled to Solid Oxide Fuel Cell (SOFC) exhausts, for biomass culture. This biorefinery concept can be exploited towards the complete integration of a waste treatment plant. The work concern the preliminary tests assessed to identify the condition to obtain microalgal growth on dry digestate from anaerobic digestion of organic waste and CO2 remaining after power and heat production by fuel cells biofixation. The results of digestate pretreatment and dilution, inoculum: digestate ratio and CO2 supply system were reported. Each test was controlling operating temperature and light intensity using a common green alga, Chlorella vulgaris. Different tests were performed for testing digestate dilution (from 1:20 to 1:70) and for defining microalgal inoculum concentration (9%, 20% and 32%). All trials were performed at laboratory scale. The optimal digestate pretreatment and microalgal inoculum concentration was used for achieving CO2 biofixation in an experimental reactor (15 L). The best dilution for the digestate was found to be approximately 1:70 and inoculum percentage equal to 20%.

Bioaccessibility of Zinc from Yogurt and Determination of Total Concentration Using Slurry Sampling and Flame Atomic Absorption Spectrometry

The bioaccessibility of Zn during in vitro gastrointestinal digestion from yogurt was investigated. In addition, the methodologies of sample preparation (dry and wet digestion, and slurry sampling) for the determination of total concentration of Zn in yogurt by flame atomic absorption spectrometry were also compared in this work. In comparison with digestion procedures, the proposed slurry sampling is simple and less time-consuming procedure. The limit of quantification determined was 1.3 µg g-1. The concentrations of Zn in the Brazilian yogurt ranged from 3.40 to 5.62 µg g-1. The percentage of the bioaccessible fraction of Zn from the samples ranged from 10 to 26%. This corresponds to an average daily intake of less than 2% of the metal for adults and children, suggesting that the Brazilian yogurt contributes with a low amount of Zn for the human diet.

Nutritional potential of bamboo leaves for feeding dairy cattle

ABSTRACT Feed shortage during the dry season in the highlands of Madagascar negatively impacts the dairy cattle productivity, as well as the farmers’ income. Bamboo can produce a high quantity of biomass and could be an alternative way to increase the fodder supply for cattle. The present study aimed to assess the compositional information and the optimal rate of bamboo as fodder for dairy cattle. Leaf samples from nine bamboo species were collected to determine their chemical composition and nutritive value. A feeding experiment was also conducted using ten dairy cows, over ten weeks. Bamboo leaves were mixed with maize silage in five proportions: SIL0:BAM100, SIL25:BAM75, SIL50:BAM50, SIL75:BAM25 and SIL100:BAM0. The contents of dry matter, total ash and crude protein in the bamboo leaves were, respectively, 44.5-64.6 %, 6.68-18.5 % and 7.71-15.4 %. In the feeding trial, the dry matter intake of bamboo leaves was 1.6-7.1 kg per day, with an average of 4.8 kg per day. The dry matter apparent digestibility of bamboo leaves was 37.4-56.4 %. The milk production reached 13.6-14.4 L per cow, per day, but there was no significant difference concerning the rate of bamboo leaves in the mixed diet (p &gt; 0.05). The introduction of bamboo leaves into the ruminants diet did not affect their milk production.

PSXIII-37 A comparison of different methods of estimation of dry fecal output in dogs.

Total fecal collection (TFC) is the gold standard to estimate nutrient digestibility; however, it is difficult to collect all fecal material, especially for animals housed in confined space or that are prone to coprophagy. Instead, markers can be used to estimate digestibility. Markers can include intrinsic diet components like acid insoluble acid (AIA) or added to the diet like chromium sesquioxide (CR) or titanium dioxide (TI). These elements don’t have a physiological function, and are not digested, or absorbed by the animal. Chromium sesquioxide is most commonly used. However, it is a known carcinogen to workers and animals over extended exposure periods. Titanium dioxide (TI) is a food coloring generally recognized as safe (GRAS) that conforms to the required features needed for a marker. Our hypothesis was that TI would be a preferred marker to estimate digestibility among the other methods. Therefore, the objective of this meta-analysis was to compare the different methods to estimate digestibility across several studies. Data from four different digestibility experiments using the same animals, experimental procedures, and design were compiled and analyzed. Using the GLM procedure (SAS v. 9.4) Pearson correlation coefficients for dry fecal output between TFC, CR, TI, and AIA were calculated with multivariate analysis of variance, on two response variables: experiment and dog. All method correlations were significant (P<0.0001). Although significant, TFC dry fecal output had a low correlation with AIA (R=0.5878), while highly correlated with CR and TI (R=0.8041 and R=0.8771, respectively). Acid insoluble ash had moderate correlation with CR and TI (R=0.7282 and R=0.7472, respectively). Fecal output of CR was highly correlated with TI (R=0.8834). Titanium oxide had the highest correlation coefficients with all methods and given it is GRAS; it should be considered a preferred method to estimate dry fecal output and nutrient digestibility in dogs.

Evaluation of effect of probiotics mixture supplementation on growth performance, nutrient digestibility, faecal bacterial enumeration, and noxious gas emission in weaning pigs

A total of 180 twenty-eight-day-old weaning pigs [Duroc × (Yorkshire × Landrace)] with an average body weight of 7.62 ± 1.25 kg were used in a 42-day trial to evaluate the effect of probiotics mixture supplementation on weaning pigs. Pigs were randomly allotted to one of four dietary treatments: (1) CON, basal diet, (2) T1, CON + 0.1% probiotics mixture, (3) T2, CON + 0.2% probiotics mixture, and (4) T4, CON + 0.3% probiotics mixture. Increasing dietary inclusion of probiotics mixture levels linearly increased average daily gain (ADG) and average daily feed intake (ADFI) during day 0–7 as well as ADG and gain to feed ratio (G:F) during day 8–21 (p < .05). There was a quadratic effect in improving ADFI during day 0–7, day 22–42, and ADG during day 8–21 (p < .05). In addition, increasing inclusion of probiotics mixture levels in the diets linearly increased (p < .05) dry matter (DM), nitrogen (N), energy digestibility, and faecal Lactobacillus counts and decreased Escherichia coli counts and ammonia (NH3) emission. However, no significant differences were observed in ADG, ADFI, G:F during day 22–42, and day 0–42 except for a quadratic increase of ADFI for day 22-42 (p < .05). Feeding the pigs with the diets containing different probiotics mixture levels did not affect the faecal hydrogen sulfide emission (p>.05). In conclusion, increasing inclusion of probiotics mixture up to 0.3% linearly improved growth performance during day 0–7 and day 8–21. Pigs fed the diets with probiotics mixture suplementation improved the nutrient digestibility, faecal bacterial enumeration, and decreased NH3 emission.HighlightsProbiotics mixture supplementation increased growth performance and nutrient digestibility in weaning pigs.Increased fecal Lactobacillus and reduced E. coli counts.Reduced fecal ammonia emission that can contribute in reducing environmental pollution.

Recovery of Zr, Hf, Nb from eudialyte residue by sulfuric acid dry digestion and water leaching with H2O2 as a promoter

Following the initial hydrometallurgical extraction of rare earth elements from the eudialyte mineral, the residue is known to contain additional valuable metals. In this reported study, a two-stage acidic treatment was investigated to extract Zr, Hf, Nb from the eudialyte residue. The objective was to obtain high recovery yields with a low consumption of acid, so the proposed preprocessing step was sulfuric acid dry digestion, which was held above the boiling point of water. The treated residue was then leached with water and H2O2 was added to promote the leaching of Zr, Hf and Nb. It was found that the H2O2 increased the oxidation potential of the acidic system, which assisted the decomposition of the mineral phases that contained Zr, Hf and Nb. In addition, the H2O2 acted as a reaction promoter by providing O22– ions that formed complexes with the cations, shifted the reaction equilibrium and inhibited hydrolysis of Nb(IV). The QEMSCAN, XPS and SEM analysis were used to reveal the mineralogical characteristics of the solid samples. These characteristics demonstrated the chemical changes that occurred during extraction and helped to explain the mechanisms at work during the processes. The SEM analysis results showed that metals sulfate salts and quartz were present after the digestion process. The treated eudialyte residue leached the soluble salts into solution, whereas the quartz remained in the residue. After optimizing the treatment parameters by varying the process conditions it was found that the eudialyte extract produced 89.1% Zr, 81.2% Hf and 71.2% Nb and the most suitable process parameters were: digestion conditions: H2SO4/eudialyte residue: 25 ml/100 g, water/eudialyte residue: 20 ml/100 g, 110 °C, 4 h; leaching conditions: L/S: 3:1, H2O2/eudialyte residue: 10 ml/100 g, room temperature, 1 h.

Soil Analysis of Roads near Environment Soil for Lead Pollution Assessment, Study Case: Tehran- Karaj Highway

There are different pollution sources, which affect soil including transportation, especially in highways. These effects can be assessed by Environmental Impact Assessment. In this study, seven sampling stations were selected in different distances (0, 10, 20, 50, 100 meter) along Tehran- Karaj highway. Samples were collected and their concentrations of Pb were measured using a FAAS after dry acid digestion. It was observed that the highway had a negative impact on the peripheral soil. These impacts were higher in Tehran with average lead concentrations, and declined by moving toward Karaj. Moreover, the average concentration of lead in soil significantly decreased by increasing distance from the roadside.&#x0D; Highest lead concentration was in station (E) in the middle of the road with an average of 160.50 mg/kg. The highest average concentrations were observed in soils of the roadside with an average of 115.25 mg/kg. The highest concentration was also observed in station (B) and in the roadside, with a concentration of 302 mg/kg, which was above the international allowable limits. Tehran- Karaj highway is in the list of the most polluted roads in the world and it must be concerned for its lead pollution, especially in the roadside. Essential steps for controlling the negative impacts must be taken including the expansion of green-space along the highway.

Evaluation of Digestibility and Nutritive Potentials of Citrus sinensis and Musa paradisiaca biologically treated with Three White Rot Fungi

Objective To investigate the digestibility and nutritive quality of sweet orange and ripe plantain peels treated with the spawns of Lentinus squarrosulus, Pleurotus pulmonarius and Pleurotus ostreatus (HK35) incubated for 0, 30 and 60 days. Methodology and Results: 25g of each milled substrates were weighed into thoroughly washed jam bottles and 70ml-distilled water was added. The bottle was immediately covered with aluminium foil, fresh weights of the bottles determined and the bottles were sterilized in the autoclave at 121oC for 15 min. The substrate bottles were left to cool and each was inoculated with 5g of pure mushroom spawn at the centre and incubated at 28±20C for 30 and 60 days incubation periods while the control (0 days) was left un-inoculated. The samples were prepared in triplicates. The dry matter, lignin, cellulose, hemicellulose, pH, digestibility and organic matter content were determined using standard techniques. The lowest lignin level of 54.86% was observed in peels treated with P. ostreatus after 30 days incubation period while 19.20% and 8.60% were the lowest cellulose and hemicelluloses levels recorded for peels treated with L. squarrosulus after 60days and 30 days respectively. The pH level increased as the incubation period increased with the highest increment of 6.82 recorded for plantain peels treated P.pulmonarius and the lowest organic matter content of 8.79% observed in plantain peels treated with L. squarrosulus. The dry matter content increased as the incubation period increased. The greatest digestibility (26.50%) was observed in plantain peels treated with L.squarrosulus. Conclusion and Applications of Results: The ability of the fungi to improve these components of the peels varied among the species as increased digestibility, reduced lignin and pH contents were recorded. Hence, making these wastes better sources of feed for ruminants’ production. Keywords: Biological treatment, Pleurotus ostreatus, P. pulmonarius, Lentinus squarrosulus, Plantain peels, Orange peels.

Inhibition of volatile fatty acids on methane production kinetics during dry co-digestion of food waste and pig manure

Compared with wet digestion, dry digestion of organic wastes reduces reactor volume and requires less energy for heating, but it is easily inhibited by high volatile fatty acid (VFA) or ammonia concentration. The inhibition on methane production kinetics during dry co-digestion of food waste and pig manure is rarely reported. The aim of this study was to explore the inhibition mechanisms and the microbial interactions in food waste and pig manure dry co-digestion systems at different inoculum rates (25% and 50% based on volatile solids) and food waste/pig manure ratios (0:100, 25:75, 50:50, 75:25 and 100:0 based on volatile solids). The results showed that the preferable operation conditions were obtained at the inoculum rate of 50% and food waste/pig manure ratio of 50:50, with a specific methane yield of 263 mL/g VSadded. High VFA concentration was the main inhibition factor on methane production, and the threshold VFA inhibition concentrations ranged 16.5–18.0 g/L. Syntrophic oxidation with hydrogenotrophic methanogenesis might be the main methane production pathway in dry co-digestion systems due to the dominance of hydrogenotrophic methanogens in the archaeal community. In conclusion, dry co-digestion of food waste and pig manure is feasible for methane production without pH adjustment and can be operated stably by choosing proper operation conditions.