Volatile Fatty Acid Concentrations Research Articles

Influence of Mesophilic Bacteria Inoculation with Chicken Manure for Biogas Production Enhancement in Anaerobic Digestion (AD) Process

The objective of this study is to investigate biogas production by anaerobic digestion using mesophilic bacteria mixed with Palm Oil Mill Effluent (POME). This project aims to determine the volume of biogas generation and volatile fatty acid (VFA) production from chicken manure via the anaerobic digestion process. Anaerobic digestion (AD) of chicken manure (CM) often faces obstacles, including high total ammonia nitrogen (TAN) concentration, inorganic soil particles, and wood chips. The digestion process was carried under batch mode conditions in Scott bottles of 1.0 L active volume. The bottles were immersed in a water bath to control their temperature at 37℃. The characteristics of total solid, volatile solid of mass fraction, pH, and temperature on the amount of biogas produced were studied. The investigation showed that biogas production can be enhanced by inoculation of another material. The optimum biogas composition in the AD system was recorded by Inoculum I, which was achieved on Day 2 at 560 mL/L. The highest cumulative methane yield was observed in the leachate with Inoculum (I), which was 8976 mL/gVS, while the CML produced 4 mL/g VS. The anaerobic digestion (AD) process augmented with inoculum demonstrated heightened efficacy in biogas generation and VFA concentration reduction during the acidogenic phase, surpassing the observed performance in chicken manure leachate.

Effect of Adding Fermented Juice of Epiphytic Lactic Acid Bacteria Prepared with Different Sources of Soluble Carbohydrates on Fermentation Characteristics of Wheat Straw Silage, Rumen Fermentation and Nutrients Digestibility by Awassi Lambs

This study was conducted to determine the effect of using different sources of water soluble carbohydrates (WSC) in preparation of fermented juice of epiphytic lactic acid bacteria (FJLB) added at ensiling on fermentation characteristics of wheat straw silages (WSS), rumen fermentation and nutrients digestibility by Awassi lambs. The FJLBs were prepared from wild reed plant with glucose at 2% (w/v, FJLB-G), cane molasses at 5% (w/v, FJLB-M) or date molasses at 5% (w/v, FJLB-D). Wheat straw were ensiled for 45 days with addition of FJLBs at level of 1%, for control WSS, distilled water was added at similar quantity as FJLB (WWS-C). Urea and molasses were added to all WSS at level of 1 and 10% on dry matter (DM) basis. Twelve lambs were used in 4 treatments with 3 lambs per each. Lambs were fed concentrate diet at 3% of their BW with free allowances of WSS. Results revealed that ensiling WS with FJLBs improved silage fermentation as evidenced by lower (P<0.01) pH and ammonia nitrogen (NH3-N) concentration together with higher (P<0.01) lactic acid (LA) and volatile fatty acids (VFA) concentrations. Higher (P<0.01) digestibilities of most nutrients including cell wall components were associated with lambs fed WSS-M and WSS-D as compared with those fed WSS-G and WSS-C. However, higher (P<0.01) organic matter (OM) and crude protein (CP), digestibilities were recorded by lambs fed WSS-M. Moreover, ruminal NH3-N and VFA were positively influenced by feeding WSS prepared with FJLB in general, FJLB-M and FJLB-D in particular.

Solid-State Fermentation with White Rot Fungi (Pleurotus Species) Improves the Chemical Composition of Highland Barley Straw as a Ruminant Feed and Enhances In Vitro Rumen Digestibility.

Lignin degradation is important for enhancing the digestibility and improving the nutritive quality of ruminant feeds. White rot fungi are well known for their bioconversion of lignocellulosic biomass. The objective of this paper was to evaluate whether Lentinus sajor-caju, Pleurotus ostreatus, Phyllotopsis rhodophylla, Pleurotus djamor, Pleurotus eryngii, and Pleurotus citrinopileatus treatments altered the chemical compositions of highland barley straw constituents and enhanced their nutritional value as a ruminant feed. All white rot fungi significantly increased the relative crude protein (CP), ethyl ether extract (EE), starch, soluble protein (SP), and non-protein nitrogen (NPN) contents but decreased the ash, neutral detergent fiber (NDF), acid detergent fiber (ADF), acid detergent lignin (ADL), and acid detergent insoluble protein (ADFIP) contents. In addition, L. sajor-caju treatment increased (p < 0.001) the levels of PA, PB2, PB3, CA, CB1, CB2, and CNSC, but reduced (p < 0.001) the PC and CC in the solid-state fermentation of highland barley straw. Maximum ligninlysis (50.19%) was optimally produced in the presence of 1.53% glucose and 2.29% urea at 22.72 ℃. The in vitro dry matter digestibility and total volatile fatty acid concentrations of fermented highland barley straw, as well as the fermentability, were optimized and improved with L. sajor-caju, which degraded the lignocellulose and improved the nutritional value of highland barley straw as a ruminant feed.

Evaluation of the additive effects of volatile fatty acids and moderate heat treatment for enhancing the inactivation of vegetative cells and spores of Clostridium perfringens by flow cytometry

ObjectivesClostridium perfringens is a well-known spore-forming bacterium that can resist the environment. A mixture of volatile fatty acids or thermal treatments can interact with these bacteria. The aim of this study was to evaluate the effects of different volatile fatty acid concentrations and moderate heat treatment on Clostridium perfringens sporulation. MethodsA pure culture of Clostridium perfringens type A in Duncan Strong medium was treated with a mixture of volatile fatty acids at several concentrations. A thermal treatment was also tested. To evaluate the effects, a double staining method was employed, and treatments on Clostridium perfringens were analysed by flow cytometry. ResultsModerate heat treatment destroyed vegetative forms but had no effect on sporulating forms. Volatile fatty acids combined with moderate heat treatment inhibited Clostridium perfringens sporulation. ConclusionsThe use of flow cytometry as an original method for evaluating the treatment of Clostridium perfringens is of interest because of its simplicity, short time to obtain results, and the level of information provided on the microbial population (impact on metabolism). A combination of mild treatments (moderate heat treatment + volatile fatty acids) to decrease the Clostridium perfringens concentration when these bacteria sporulate is a very promising finding for inhibiting Clostridium perfringens propagation.

Impacts of seasonal variation on volatile fatty acids production of food waste anaerobic fermentation

This study aims to investigate the influence of seasonal variations on Volatile fatty acids (VFAs) production from food waste (FW) and to quantify their impact. Results of batch experiments with external pH control indicated that the properties of FW exhibited significant seasonal variations and were markedly different from kitchen waste (KW). The spring group demonstrated the highest VFA concentration and VFA/SCOD, at 31.24 g COD/L and 92.20 % respectively, which were 1.22 and 1.27 times higher than those observed in the summer season. The combined proportion of acetic acid and butyric acid accounted for 81.10 % of the total VFAs in spring, suggesting the highest applicability to the carbon source. The VFA content of all seasonal groups in descending order was butyric acid, propionic acid and acetic acid. Carbohydrates, along with spicy and citrusy substances, promoted the conversion of total VFA and butyric acid, while proteins and lipids favored the production of acetic acid and propionic acid.

Effect of Supplementing a Bacillus Multi-Strain Probiotic to a Post-Weaning Diet on Nutrient Utilisation and Nitrogen Retention of Piglets

Probiotics are suggested to improve pig health, nutrient utilisation, performance, and they may reduce nitrogen (N) pollution. However, the effectivity of a single strain might be different from that of a multi-strain. The study was conducted to investigate the effect of a novel Bacillus multi-strain on nutrient digestibility, energy utilisation, and N retention in weaned piglets using an European diet. The experiment consisted of a control diet (CD) and a supplemented diet (SD). The probiotic used for SD consisted of B. amyloliquefaciens—516 and B. subtilis—541. A total of eight boars/treatment were weaned (day 0; 8.5 kg body weight). Only boars were used to ease the collection of urine. Until day 10, piglets were fed ad libitum and were housed in pairs; from day 11, piglets were fed semi ad libitum (feeding level 3.2× metabolic body weight) and were housed individually. From day 14, faecal and urine were collected twice daily. Piglets were humanely euthanised at day 19 (15.0 kg bodyweight) after which the jejunum, ileum, and colon content were collected. In faeces, the apparent total tract digestibility (ATTD) of, amongst others, DM, organic matter (OM), crude protein (CP), non-starch polysaccharides (NSP), and subsequently net energy (NE) were calculated using titanium dioxide as an indigestible marker. In the jejunum and ileum, the apparent digestibility of CP was estimated, and in the ileum, the apparent AA digestibility was measured. In urine, the N content was measured to determine N retention. The volatile fatty acid (VFA), branched-chain fatty acid (BCFA), and lactic acid content were analysed in the colon and faeces. The apparent CP digestibility in the jejunum and ileum was not affected by treatment (p &gt; 0.05), and no effect was observed on the apparent ileal digestibility of AA (p &gt; 0.05). Supplementation with the multi-strain probiotic improved the ATTD of DM (p = 0.01; +1.3%) and OM (p = 0.02; +1.2%) and tended to improve the ATTD of CP (p = 0.10; +2.2%) and NSP (p = 0.07; +1.9%). The multi-strain probiotic also improved the NE value (p = 0.02; +0.2 MJ/kg DM) and improved N retention (p = 0.05; +1.6%). Supplementation did not influence the VFA, BCFA, and lactic acid content in the faeces (p &gt; 0.05). However, in the colon, supplementation did influence the lactic acid content (lower; p = 0.01) and tended to influence the valeric acid content (higher; p = 0.09). In conclusion, results from the current study suggest that the multi-strain probiotic has the potential to contribute to improve nutrient efficiency in weaned piglets. More research needs to be conducted to identify the impact of the improved nutrient utilisation on gut health in post-weaned pigs as well as environmental pollution.

Applying sludge hydrolysate as a carbon source for biological denitrification after composition optimization via red soil filtration

Sludge hydrolysate, the byproduct generated during sludge hydrothermal treatment (HT), is a potential carbon source for biological denitrification. However, the refractory organic matters and the nutrient substances are unfavorable to the nitrogen removal. In this study, effects of HT conditions on the hydrolysate properties, and the hydrolysate compositions optimization via red soil (RS) filtration were investigated. At HT temperature of 160–220 °C and reaction time of 1–4 h, the highest dissolution rate of organics from sludge to hydrolysate achieved 70.1 %, while the acetic acid dominated volatile fatty acids (VFAs) was no more than 5.0 % of the total organic matter content. The NH4+-N and dissolved organic nitrogen (DON) were the main nitrogen species in hydrolysate. When the hydrolysate was filtered by RS, the high molecular weight organic matters, DON, NH4+ and PO43− were effectively retained by RS, while VFAs and polysaccharide favorable for denitrification were kept in the filtrate. When providing same COD as the carbon source, the filtrate group (Fi-Group) introduced lower concentrations of TN and humic substances but higher content of VFAs. This resulted in TN removal rate (57.0 %) and denitrification efficiency (93.6 %) in Fi-Group higher than those in hydrolysate group (Hy-Group), 39.4 % and 83.7 %, respectively. It is noticeable that both Hy- and Fi- Groups up-regulated most of denitrification functional genes, and increased the richness and diversity of denitrifying bacteria. Also, more denitrifying bacteria genera appeared, and their relative abundance increased significantly from 3.31 % in Control to 21.15 % in Hy- Group and 31.31 % in Fi-Group. This indicates that the filtrate is a more suitable carbon source for denitrification than hydrolysate. Moreover, the pH rose from 4.6 ± 0.14 to 6.5 ± 0.05, and the organic carbon, TN, TP and cation exchange capacity (CEC) of RS increased as well after being filtered, implying that the trapped compounds may have the potential to improve soil quality. This study provides a new insight for hydrolysate application according to its composition characteristics, and helps make the most use of wasted sludge.

Effect of different doses of cobalt on rumen digestion in cattle

Optimization of mineral nutrition is a necessary measure to maintain high productivity of beef cattle which often lack minerals in their feed. The innovative base in this case can be ultrafine particles of essential elements characterized by high bioavailability in a small dose. The effect of ultrafine Co3O4 particles on the digestibility of dry matter of feed in the in vitro system (artificial rumen), the amount of volatile fatty acids, nitrogen forms (total, non-protein, ammonia, urea, protein) and on the amino acid composition (arginine, lysine, methionine, alanine, glycine) of animal rumen fluid was studied. The research was conducted in 2023. Cattle of the Kazakh white-headed breed aged 11-12 months with an average weight of 265-275 kg were used as an object of research. It was found that in in vitro studies, dry matter digestibility of feed was 9.0% higher at a concentration of 0.36 g/mL of Co3O4 ultrafine particles. Analysis of volatile fatty acid concentration showed that this dosage increases acetic acid, propionic acid, butyric acid, valerianic acid, and caproic acid. The introduction of ultrafine Co3O4 particles increased the content of protein nitrogen and total nitrogen in the experimental animals, indicating the intensification of rumen microbiocenosis. At introduction of ultrafine Co3O4 particles, shifts in the amino acid composition of the rumen contents were observed, which may be caused by the changes in the nature of nitrogenous substances transformation in the digestive tract. It is concluded that the use of ultrafine Co3O4 particles has a positive effect on the digestive processes in the rumen.

Feasibility Study of Using Excess Sludge Fermentation Broth as a Co-Metabolic Carbon Source for 2,4,6-Trichlorophenol Degradation

Excess sludge fermentation is a commonly employed method for carbon sources in wastewater treatment plants, but its use as a carbon source for chlorophenol removal has been relatively underexplored. In this study, a laboratory-scale sludge fermentation SBR (FSBR) was integrated with a 2,4,6-trichlorophenol (2,4,6-TCP) degradation SBR (DSBR), resulting in a stable removal of 2,4,6-TCP without the need for external carbon sources. In this coupled system, the concentrations of volatile fatty acids in FSBR remained constant, with acetic acid, propionic acid, butyric acid, and valeric acid concentrations reaching 322.04 mg COD/L, 225.98 mg COD/L, 274.76 mg COD/L, and 149.58 mg COD/L, respectively, and the acid production efficiency increased to 88.40%. Throughout the 110-day operational period, the activated sludge concentration in the DSBR was consistently maintained at 3021 ± 110 mg/L, and the sludge SVI remained stable at 70 mL/g. The maximum amount of 2,4,6-TCP removed reached 240.13 mg/L within a 12 h operating cycle. The use of excess sludge fermentation can completely replace commercial carbon sources for 2,4,6-TCP removal, leading to cost savings in chlorophenol treatment and broadening the applicability of this technology.

Ruminal pH sensing for monitoring volatile fatty acid concentrations in response to short-term dietary disruption

The purpose of this study was to investigate the potential of using ruminal pH measurements to track time-series ruminal volatile fatty acid (VFA) concentrations occurring in response to short-term dietary disruption. Four ruminally cannulated dry Holstein dairy cows were individually housed and assigned to 4 treatments in a Latin square design. Treatments differing in forage-to-concentrate (F:C) ratio (100:0 to 55:45) were used because they were expected to result in large differences in VFA concentration, over which the relationships between pH and VFA could be robustly evaluated. Each sampling period lasted 36 h. Animals were removed from pasture and fasted for 24 h, after which time they were fed their treatment ration for 2 h and sampled for rumen fluid hourly for 12 h. Rumen fluid samples were analyzed immediately for pH, frozen, and subsequently analyzed for VFA concentrations using gas chromatography. Animals were returned to pasture for 7 d between sampling periods. To confirm that the short-term dietary disruptions resulted in expected variation in VFA concentrations, mean VFA concentrations during each animal period (n = 16) were analyzed using a linear mixed effects model with fixed (linear and quadratic) effects for F:C ratio and random effects for animal and period. Results indicated significant changes in VFA concentration across F:C ratio, but no significant shifts in VFA molar proportions, perhaps due to the short-term nature of the feeding protocol. To explore opportunity to use pH measurements to explain variability in VFA concentrations in real time across dietary conditions, a linear mixed-effect model was used to link the time-series measurements (n = 207). The VFA concentrations were analyzed with linear mixed effect models using linear and quadratic terms for pH, and random effects for animal and period. These models had poor accuracy, with residual error variance ranging from 21% to 38%, and residuals patterning significantly with F:C ratio. The data suggest that pH may lack reliability for VFA prediction in short-term feeding scenarios differing considerably in F:C ratio.

Mono-Digestion of 5-Hydroxymethylfurfural Process-Wastewater in Continuously Operated Anaerobic Filters: A Cascade Utilization Approach

A proper remedy for the overexploitation of biomass and biobased materials in the bioeconomy is the valorization of biorefineries’ side streams into meaningful products. Hence, in pursuit of a cascade utilization of renewables, a unique biorefinery byproduct was investigated for its biogas potential, specifically methane, in continuously operated anaerobic filters. For this purpose, 5-Hydroxymethylfurfural process-wastewater, after supplementation of necessary nutrients, was diluted down to 10, 20, 30, 40, and 50 gCOD/L concentrations and thereafter tested individually at 43 °C and 55 °C. Maximum methane conversion efficiency at either temperature was observed for test substrates with 10 gCOD/L and 20 gCOD/L concentrations. At 43 °C, the anaerobic filters exhibited their highest biogas yields when supplied with the 30 gCOD/L feedstock. Further exposure of the mesophilic and thermophilic consortia to the ensuing 5-Hydroxymethylfurfural process-wastewater dilutions compromised the stability of the anaerobic process due to the soaring concentrations of short-chained volatile fatty acids. The supplementation of necessary nutrients to unlock the methane potential of the given recalcitrant substrate appears insufficient. Techniques like micro aeration, photolysis, or the use of activated carbon in the fixed bed might have the ability to enhance the biochemical methane conversion of such feedstock; otherwise, the introduction of trace elements alone may be adequate if aiming for platforms (volatile fatty acids) via anaerobic technologies.

Impact of corn silage substitution for dry alfalfa on milk fatty acid profile, nitrogen utilization, plasma biochemical markers, rumen fermentation, and antioxidant capacity in Mahabadi lactating goats

This study aimed to investigate the effects of substituting conventional dry forage with corn silage, a more cost-effective supplementary feed, on a variety of parameters in lactating Mahabadi goats, native to arid and semi-arid regions. A total of fifty lactating Mahabadi goats, aged between 2 and 5 years and weighing an average of 45.3 ± 7.20 kg, were randomly allocated into two experimental groups. The experimental treatments consisted of a control diet and a diet incorporating corn silage at 20 % of dry matter (DM). Various measurements were conducted to assess milk compositions, fatty acid profiles, rumen fermentation parameters, selected plasma biochemical parameters, nitrogen balance, and antioxidant capacity. The results revealed that the substitution of dry forage with corn silage had no statistically significant impact on milk yield, dry matter intake (DMI), body weight, as well as the proportions of monounsaturated and unsaturated fatty acids, and specifically C18:1C9 in milk, non-esterified fatty acid content in milk, rumen concentration of volatile fatty acids (VFA), microbial nitrogen, and nitrogen balance (p > 0.05). Nonetheless, this substitution led to a reduction in the percentage of milk polyunsaturated fatty acids and plasma urea nitrogen content (p < 0.05). It is noteworthy that goats fed with corn silage exhibited a notably higher antioxidant capacity in rumen liquor (p < 0.05), plasma, and milk (p < 0.01) compared to those receiving the control diet. The substitution of conventional dry forage with corn silage exhibited no adverse effects on the performance of lactating Mahabadi goats. On the contrary, it contributed to an enhancement in the antioxidant status. These findings offer valuable insights for optimizing dietary composition by incorporating corn silage at 20 % of DM, thereby improving milk quality, reducing costs, and promoting overall health in lactating goats, particularly within arid and semi-arid regions.

Exhalomics as a noninvasive method for assessing rumen fermentation in dairy cows: Can exhaled-breath metabolomics replace rumen sampling?

Previously, we used secondary electrospray ionization-mass spectrometry (SESI-MS) to investigate the diurnal patterns and signal intensities of exhaled (EX) volatile fatty acids (VFA) of dairy cows. The current study aimed to validate the potential of an exhalomics approach for evaluating rumen fermentation. The experiment was conducted in a switchback design, with 3 periods of 9 d each, including 7 d for adaptation and 2 d for sampling. Four rumen-cannulated original Swiss Brown (Braunvieh) cows were randomly assigned to 1 of 2 diet sequences (ABA or BAB): (A) low starch (LS; 6.31% starch on a dry matter basis) and (B) high starch (HS; 16.2% starch on a dry matter basis). Feeding was once per day at 0830 h. Exhalome (with the GreenFeed System), and rumen samples were collected 8 times to represent every 3 h of a day, and EX-VFA and ruminal (RM)-VFA were analyzed using SESI-MS and HPLC, respectively. Furthermore, the VFA concentration in the gas phase (HR-VFA) was predicted based on RM-VFA and Henry's Law (HR) constants. No interactions were identified between the types of diets (HS vs. LS) and the measurement methods on daily average VFA profiles (RM vs. EX or HR vs. EX), suggesting a consistent performance among the methods. Additionally, when the 3-h interval VFA data from HS and LS diets were analyzed separately, no interactions were observed between methods and time of day, indicating that the relative daily pattern of VFA molar proportions was similar regardless of the VFA measurement method used. The results revealed that the levels of acetate sharply increased immediately after feeding, trailed by an increase in the acetate:propionate ratio and a steady increase for propionate (2 h after feeding the HS diet, 4 h for LS), and butyrate. This change was more pronounced for the HS diet than the LS diet. However, there was no overall diet effect on the VFA molar proportions, although the measurement methods affected the molar proportions. Furthermore, we observed a strong positive correlation between the levels of RM and EX acetate for both diets (HS: r = 0.84; LS: r = 0.85), RM and EX propionate (r = 0.74), and RM and EX acetate:propionate ratio (r = 0.80). Both EX-VFA and RM-VFA exhibited similar responses to feeding and dietary treatments, suggesting that EX-VFA could serve as a useful proxy for characterizing RM-VFA molar proportions to evaluate rumen fermentation. Similar relationships were observed between RM-VFA and HR-VFA. In conclusion, this study underscores the potential of exhalomics as a reliable approach for assessing rumen fermentation. Moving forward, research should further explore the depth of exhalomics in ruminant studies to provide a comprehensive insight into rumen fermentation metabolites, especially across diverse dietary conditions.

Essential Oil Blends with or without Fumaric Acid Influenced In Vitro Rumen Fermentation, Greenhouse Gas Emission, and Volatile Fatty Acids Production of a Total Mixed Ration

The growing interest in improving rumen fermentation and mitigating methane emissions necessitates the use of essential oil blends (EOB) and fumaric acid (FA). This study evaluated the synergistic effect of four EOB with or without FA supplementation on in vitro dry matter digestibility, greenhouse gas emission, and total volatile fatty acid production using inoculum from three rumen-cannulated Black Angus beef cows. The study was arranged in a 4 × 2 + 1 factorial design to evaluate the effects of the four EOB and two FA levels on a total mixed ration (TMR). The EOB dosage was 100 µL while FA was added at 3% of total mixed ration. The EOB × FA interaction (p &lt; 0.05) influenced the dry matter, neutral detergent fiber, and hemicellulose degradabilities. All the EOB and FA (EFA) treatments decreased (p &lt; 0.001) the dry matter degradability compared to the control (TMR substrate only). The EFA4 treatment reduced the neutral detergent fiber and hemicellulose degradabilities compared to the control. The ruminal pH was influenced (p &lt; 0.001) by both the EOB and FA inclusion, and the EOB × FA interaction was significant. The microbial mass was higher (p &lt; 0.001) in the EFA1, EFA4, and EOB4 compared to the control and the EOB3 treatments. The EFA1 and EOB1 produced less (p &lt; 0.001) gas than the control by 29.1 and 32.1%, respectively. Compared with the control, the EFA1 and EOB1 treatments decreased (p &lt; 0.001) methane gas by 90.8% and 86.4%, respectively, while the carbon dioxide was reduced (p = 0.004) by 65.7 and 57.9%, respectively. The EOB × FA interaction was significant (p &lt; 0.001) for the total and individual volatile fatty acid concentrations. The inclusion of FA increased the propionate concentration by 9.5% and decreased (p = 0.02) the acetate concentration by 4%. In summary, the synergistic effect of the EOB and FA offers an effective way to reduce greenhouse gas emission and enhance total volatile fatty acids.

Metagenomics-Based Analysis of the Effect of Rice Straw Substitution for a Proportion of Whole-Plant Corn Silage on the Rumen Flora Structure and Carbohydrate-Active Enzymes (CAZymes)

The purpose of this study was to investigate the effects of replacing a portion of whole-plant corn silage with straw on the rumen microbial community structure and carbohydrate-active enzyme activity. The experiment employed a single-factor randomized trial design, with eight late-lactation Chinese Holstein dairy cows being randomly divided into two groups of four replicates each. The control group (CS group) was fed a diet consisting of alfalfa silage and a mixture of alfalfa and whole-plant corn silage, while the experimental group (RS group) received a diet in which one-third of the corn silage was replaced with straw while keeping the other components unchanged. The experiment lasted for a total of 21 days, with a pre-feeding period of 14 days and a formal period of 7 days. The rumen fluid collected on day 21 was used for the rumen fermentation parameters and metagenomic analysis. The concentrations of acetic acid, propionic acid, butyric acid, and total volatile fatty acids (TVFA) in the rumen of RS group cows were significantly lower than those in the CS group (p &lt; 0.01). The ratio of acetic acid to propionic acid was significantly higher in the RS group compared to the CS group (p &lt; 0.01). Metagenomic sequencing revealed that at the genus level, compared to the CS group, the abundance of unclassified bacteria, Bacteroides, Alistipes, Butyrivibrio, Chlamydia, Fibrobacter, unclassified Ruminococcaceae, and unclassified Bacteroidetes in the rumen of RS group cows increased, while the abundance of Eubacterium decreased ([LDA &gt; 3.6], p &lt; 0.05). Compared to the CS group, the enzymatic activities of α-L-arabinofuranosidase (EC3.2.1.55), β-xylosidase (EC3.2.1.37), β-glucosidase (EC3.2.1.21), β-glucosylceramidase (EC3.2.1.45), xylanase (EC3.2.1.8), and arabinanase (EC3.2.1.99) in the rumen of RS group cows increased (p &lt; 0.05). According to the correlation analysis, Alistipes, Bacteroides, and Butyrivibrio showed a significant negative correlation with propionic acid (p &lt; 0.05) and a significant positive correlation with the acetic acid-to-propionic acid ratio (p &lt; 0.05). They also showed a significant positive correlation with GH2, GH3, GH20, GH29, GH43, GH78, GH92, CE1, GT4, β-glucosidase (EC3.2.1.21), α-L-arabinofuranosidase (EC 3.2.1.55), β-xylosidase (EC 3.2.1.37), β-glucosylceramidase (EC 3.2.1.45), xylanase (EC 3.2.1.8), and arabinanase (EC 3.2.1.99) (p &lt; 0.05). In summary, straw can not only alter the composition and structure of the rumen microbiota in cows but also affect the relative abundance of CAZymes at different levels within the rumen. Cows may, thus, potentially improve the degradation efficiency of straw diets by increasing the abundance of certain rumen microbiota and enzymes.

223 Impacts of Active Dry Yeast (Saccharomyces cerevisiae) on Gut Permeability in Finishing Beef Cattle

Abstract The objectives of this study were to examine the impacts of active live yeast (Saccharomyces cerevisiae) as a dietary feed additive on dry matter intake, feed sorting, gut permeability, ruminal pH and volatile fatty acids (VFA) concentration, as well as fecal pH and VFA concentration in cattle fed a high-grain finishing diet and subjected to a ruminal acidotic challenge. Fifteen Hereford X Charolais heifers were blocked by BW into three blocks. Heifers were randomly assigned within block to one of two dietary treatments; CON (no additive), or YST (3 g· animal-1· day-1 of active live S. cerevisiae) added to a steam-flaked corn diet (83% steam-flaked corn, 8% wheat straw, 5% soybean meal protein mix, 4% vitamin and minerals on a DM basis). The experimental timeline was as follows: 30 d adaptation (ADPT), 5 d baseline (BASE), 5 d ruminal acidosis challenge (CHAL), and three subsequent 5 d recovery phases (REC1, REC2, and REC3). On day 2 of each phase and days 2 and 4 of CHAL, 179 mM Cr-EDTA and 360 mM Co-EDTA were infused into the omasum and rumen, respectively, as gut permeability markers. Within each phase, in-dwelling pH probes were used to capture reticulo-ruminal pH every 5min for 96 consecutive hours, rumen fluid and fecal grab samples were collected once for every 3 h in a 24 h period, and blood was collected at 2, 4, 12, and 24 h after each Co and Cr infusion. Dry matter intake and feed sorting were measured daily for each animal. Statistical analysis was conducted using PROC GLIMMIX in SAS as a randomized complete block design with block, treatment, and phase as fixed effects and animal as a random effect. Ruminal acidosis was successfully induced using this method, as suggested by the statistically significant reduction in minimum pH and increase in pH range in the CHAL phase compared with other phases of the experiment (P ≤ 0.02). Recovery from the ruminal acidosis challenge was detected within the REC1 phase when comparing minimum pH (CHAL 5.25 vs. REC1 5.54; P = 0.001). Additionally, the sorting behavior of some particle sizes was significantly impacted by phase (P ≤ 0.01). Overall, the addition of yeast to the diet did not impact feed intake, sorting behavior, spot ruminal and fecal pH, volatile fatty acid concentrations in ruminal fluid or feces, or the uptake of Cr-EDTA and Co-EDTA. These results suggest that adding live S. cerevisiae yeast at this dose in a high-grain finishing diet does not impact feed intake, gut permeability, or the production of VFA when ruminal acidosis is induced.

Dose- and substrate-dependent reduction of enteric methane and ammonia by natural additives in vitro.

Ruminants contribute to global warming by emitting greenhouse gasses, particularly methane (CH4) which is a product of rumen fermentation. The use of feed additives able to modulate rumen fermentation is a promising strategy to reduce enteric CH4 and ammonia (NH3) emissions. Among the various strategies investigated, plant secondary metabolites (PSMs) have attracted attention due to their apparent potential to reduce enteric CH4 and NH3 emissions, and it would be possible to use such compounds as feed additives in organic production systems. In an in vitro system simulating rumen fermentation, we have tested the impact of different classes of naturally occurring PSMs; catechin and quercetin (flavonoids), salicylic acid (phenolic acid) and tannic acid (hydrolysable tannin). The PSMs were added to two different basal feeds (maize and grass silages) at three inclusion doses 1.5, 3 and 6% of the feed dry matter (DM). CH4 production was significantly lowered upon addition of quercetin to two basal feeds at doses of 3 and 6%, and this without changes in concentrations of total volatile fatty acid (VFA) produced during fermentation. Quercetin, as the only tested additive, reduced CH4 production, and when added to maize silage and grass silage, the reduction increased linearly with increasing dose, ie., by 51 and 43%, respectively, at a dose of 3% of feed DM and by 86 and 58%, respectively, at a dose of 6% of feed DM. Moreover, quercetin significantly reduced NH3 concentration by >12% at doses of 3 and 6% in feed DM irrespective of the basal feed used as compared to when the basal feeds were incubated alone. Although none of the other additives affected CH4 formation, several additives had significant impacts on concentrations of NH3 and VFAs in the incubated fluid after fermentation. This study demonstrated a dose-dependent ability of quercetin to reduce CH4 emission from rumen fermentation, however, the magnitude of the suppression of CH4 depended on the basal feed. Furthermore, quercetin reduced NH3 concentration irrespective of the basal feed type. These findings encourage to in vivo studies to verify whether quercetin can reduce CH4 emission also in cows.

200 The Effects of Whole Hemp Seed Supplementation on Health Status, Voluntary Physical Activity, Fecal Quality, and Fermentative End-Products in Healthy Adult Dogs

Abstract The cultivation and utilization of hemp and hemp-derived products have increased at a rapid pace since the enactment of the 2018 farm bill which provided changes in regulation related to cannabis. Although there are three hemp-derived ingredients that have been generally recognized as safe status for human consumption by the FDA, no ingredients have been approved by the FDA for consumption by companion animals or defined by AAFCO. Hemp seeds have the potential to act as a rich source of plant protein, polyunsaturated fatty-acids, and dietary fiber in companion animal nutrition. The objective of this study was to evaluate the effects of supplementing ground whole hemp seed in a baked chew on voluntary physical activity, fecal characteristics, fermentative-end products, and overall health status in healthy adult dogs. All animal procedures were approved by the University of Illinois Institutional Animal Care and Use Committee and were in accordance with the United States Public Health Service Policy on Humane Care and Use of Laboratory Animals. Thirty adult beagle dogs were used in a complete randomized design, with ten dogs assigned to each treatment. The dogs were fed the same commercially available, complete and balanced diet and were supplemented with one of three baked chews containing either a high inclusion of ground hemp seed (50%), a low inclusion of ground hemp seed (25%), or cellulose. The baked chews were fed at a level of 10% of the daily intake for 28 d and were formulated to be similar in macronutrient composition, approximately 25% fat, 20% protein, and 25% total dietary fiber. Duration and intensity of voluntary physical activity was measured using activity monitors for 4 d before supplementation and at the end of the supplementation period (d 24 to 27). Fasted blood and a fresh fecal sample were taken on d 0, 14, and 28 to monitor health status, blood variables, fecal characteristics and fermentative-end product concentrations. The baked chews were well accepted by the dogs with minimal intake refusals, and all dogs remained clinically healthy for the duration of the experimental period. No differences in fecal score or fecal pH were observed among the treatment groups (P &amp;gt; 0.05). The treatment did not have an effect on fecal concentrations of volatile fatty acids including acetate, propionate, butyrate, valerate, isovalerate, and isobutyrate (P &amp;gt; 0.05). Concentrations of fecal ammonia, phenols, and indoles were also similar among the groups (P &amp;gt; 0.05). No adverse effects were observed, and the data suggest that in a baked chew the whole ground hemp seed was comparable to the cellulose control.

PSXI-27 Live Yeasts Enhance Ruminal Fermentation of Fibrous Feedstuffs

Abstract Since the beginning of the present century, research results have shown that ruminant researchers have explored the idea of manipulate ruminal fermentation, trying to improve a much better metabolism of nutrients in the rumen, all of this with the aim to increase the productivity of ruminants. The main goal of this experiment was to evaluate the potential use of a savage yeast strain (Pichia guilliermondii) on the ruminal fermentation of maize stover. To accomplish the objective two in vitro treatments were examined: a) filtered rumen liquid + powdered maize stover + yeast-free culture medium, and b) filtered rumen liquid + powdered maize stover + culture medium inoculated with yeast. Samples were collected at different time, 0, 6, 12, and 24 h and examined for effects on culture pH, ammonia nitrogen (NH3-N), the fiber digestibility percentages of neutral detergent fiber (NDFD) and acid detergent fiber (ADFD), as well the digestibility of dry matter (DMD), and the concentration of volatile fatty acids (VFAs). The results showed that the addition of Levica 27 had no effect on the ruminal pH, NH3-N or the digestibility indicators (P &amp;gt; 0.05). However, at 12 h, the inclusion of Levica 27 increased (P &amp;lt; 0.05) the molar total of VFAs, and acetic and propionic acids in ruminal fluid and decreased (P &amp;lt; 0.05) the C2:C3 ratio. Our conclusion was that Pichia guilliermondii had a stimulating effect on the in vitro ruminal fermentation over a range within 6 and 12 h, a result that should be taken into account when in vivo studies are replicated with this yeast strain.

220 Assessment of the Rumen Bacterial Community in Beef Cows Differing in Feed Efficiency Across Four Feeding and Grazing Scenarios

Abstract In Alberta Canada, the mature cow-herd consumes a variety of forage-based diets; whether that be grazing pastures in spring, summer, and into the fall and winter, or preserved forage during late winter and very early spring. Residual feed intake (RFI) is a measure of the feed efficiency of individual cattle and is typically measured in a feedlot setting. We sought to evaluate how rumen bacterial communities fluctuate when animals progressed through several forage and grazing scenarios throughout the year and whether cattle with different feed efficiency have varied shift patterns of rumen bacteria. Rumen fluid samples were collected from thirty-seven Kinsella composite hybrid beef cows at the end of different feeding or grazing regimes (March: silage fed in the feedlot, June: grazing on seeded pasture, August: grazing on native grassland, and November: grazing on stockpiled native grassland). RFI values of the beef cows were measured during the feedlot period and cows were divided into three groups: high-RFI (inefficient; RFI &amp;gt; 0.33), medium-RFI (0.33 &amp;gt; RFI &amp;gt; -0.33), and low-RFI (efficient; RFI &amp;lt; -0.33). Volatile fatty acid (VFA) profiles and total bacterial populations were analyzed using gas chromatography and qPCR with universal bacteria primers, respectively. Bacterial communities were assessed using 16S rRNA gene amplicon sequencing, and the data were analyzed using QIIME2 (version 2022.11) with the SILVA 138.1 database. Rumen samples collected in June (seeded pasture) had greater (P &amp;lt; 0.05) concentrations of total VFAs, acetate, propionate, butyrate, isobutyrate, valerate, and isovalerate, compared with those collected at later dates while grazing native grassland. Rumen samples collected in March (feedlot) and June (seeded pasture) had greater (P &amp;lt; 0.05) total bacterial populations compared with samples collected in August (native grassland) and November (stockpiled native grassland). Higher microbial species richness (P &amp;lt; 0.05) was observed for rumen samples collected in March (feedlot) than those under other feeding regimens. Beta-diversity analysis revealed the rumen bacterial community of cows during the feedlot period was clearly separated (P &amp;lt; 0.05) from those grazed on pasture. A total of 22 phyla and 279 genera were identified from the rumen bacteriome. The relative abundances of five genera: Anaerosporobacter, Oribacterium, Pirellula, Robinsoniella, and uncultured taxa in Absconditabacteriales_SR1 were significantly different (P &amp;lt; 0.05) in the rumen during the different feeding or grazing periods. There were no differences in the rumen bacterial diversity and composition between RFI groups. The findings imply that feeding a homogenous diet in seeded pasture may enhance rumen fermentation and bacterial proliferation, and different grazing regimens could affect rumen bacterial diversity and abundance. Further studies are needed to identify major factors that drive the changes between different feeding and grazing regimes and to find ecological indicators of the rumen bacterial community related to feed efficiency.