Analysis Of Volatile Fatty Acids Research Articles

Improving the anaerobic digestion of sewage sludge by adding cobalt nanoparticles

ABSTRACT This work evaluated the effects of cobalt nanoparticles (CoNPs) (0.025–7 mg/gVS) on the intensification of sewage sludge anaerobic digestion (AD) using biochemical methane potential (BMP) tests. This study was motivated by the need to improve the efficiency and stability of anaerobic digestion of sewage sludge, a critical process in waste management and renewable energy production. The effects at doses less than 2 mg/gVS were not substantial, but 3–7 mg/gVS improved the performance. The maximum biogas yield was 232 mL/gVS (at a dose of 7 mg/gVS), whereas it was 132 mL/gVS in the control (zero dose). Similarly, the reductions in the volatile solids and methane contents reached maxima of 16 and 74.3%, respectively. The analyses of volatile fatty acids, redox potential, and electron transfer system activity indicated that the addition of CoNPs stimulated the early stages of AD. Finally, acetate consumption and the increase in CH4 content suggested that CoNPs positively affected system stability and acetoclastic methanogenesis. That is, CoNPs effectively intensified the behaviour and stability of the anaerobic process. The novelty of this research lies in the comprehensive evaluation of the effects of CoNPs across a wide range of doses on sewage sludge AD, providing new insights into the optimisation of this process for increased biogas production and organic matter reduction.

PSXII-29 Effect of tannins level and diet type on in vitro ruminal fermentation and methane production

Abstract The objective of the study was to evaluate the effect of four levels of a commercial product based on quebracho that contains tannins (Table 1) on three types of diets: Feedlot, Dairy Cattle, and Grazing, using the in vitro gas production technique on ruminal fermentation, dry matter digestibility and methane (CH4) production to determine its potential use as a greenhouse gas mitigation strategy in ruminants. An in vitro trial was carried out in a completely randomized block design with a factorial arrangement of 4 [dose: 0, 0.25, 0.50, and 0.75 % of Protein Enhancer (PE)] x 3 [diet types: low (LFD), medium (MFD) and high forage (HFD)]. The fermentation of each treatment was carried out in triplicate in 120 mL amber antibiotic bottles, containing 0.5 g of substrate previously deposited in nylon bags (24 µm pore size) and 60 mL of a mixture of medium and rumen fluid from three Holstein cows. Incubations were replicated in two independent runs (blocks). The gas pressure (PSI) was recorded at 1, 2, 3, 6, 9, 12, 18, 24, 30, 36, 48, 60 and 72 hours of incubation. Gas pressure data were converted to gas volume (y = mL of gas; x = gas pressure PSI). Subsequently, pH was measured, and subsamples for analysis of volatile fatty acids (VFA) by gas chromatography were collected. Methane was analyzed with a Crowcon Gas-Pro detector, while ammoniacal nitrogen with a hybrid multimodal microplate reader. The data were analyzed with the MIXED procedure of SAS, and the comparison of means was analyzed with Tukey and with orthogonal polynomials for doses. An interaction (P < 0.05) was observed between diets and PE levels for CH4 concentration (%), where the diet with a greater level of forage and the greatest level of PE (0.75%), showed the least concentration (30%, P < 0.05) compared with the control diet of dairy cattle. On average, CH4 production [mL CH4/g dry matter (DM)] were 83.3, 63.6, and 35.3 for LFD, MFD, and HFD, respectively (Table 2). As the dose of PE increased, rumen pH and N-NH3decreased (P < 0.05), and the total VFA concentration increased (linear effect, P < 0.05; Table 3). Methane production was less (30%) with the grass-based diet and the greatest level of quebracho-based product with condensed tannins, compared with the dairy cattle diet with 0% condensed tannins. The diet for feedlot cattle was more digestible and, therefore, produced more gas and a greater concentration of CH4, in contrast to the grass-based diet, which produces less CH4. It is necessary to carry out in vivo trials, particularly in grazing cattle, to evaluate the effect of the quebracho-based product on performance and in vivo methane emission. This study was partially funded by PAPIIT-DGAPA-UNAM (grant IN212523).

22 Effects of trace mineral source and chromium propionate supplementation on rumen fermentation, growth performance, and carcass characteristics in finishing beef steers

Abstract Crossbred beef steers [n = 400; body weight (BW) = 370 ± 8 kg] were used to evaluate the effects of trace mineral (TM) source and chromium propionate (Cr) on rumen fermentation characteristics, plasma glucose and mineral concentrations, performance, and carcass characteristics in feedlot steers fed a steam-flaked corn-based finishing diet. Steers were blocked by initial BW and randomly assigned within block to 1 of 4 treatments (10 steers/pen) with 10 pens per treatment. The experimental design was a randomized complete block design with a 2 x 2 factorial arrangement of treatments. Factors included: 1) TM source [sulfate or hydroxychloride (IntelliBond] Cu, Mn, and Zn TM supplemented at 18, 40, and 90 mg/kg DM, respectively) and 2) with or without supplemental Cr (KemTRACE) at 0.0 or 0.25 mg/kg DM. Steers were individually weighed on d -1 and 0 and every 28 d throughout the experiment. Jugular blood samples and rumen contents were collected from 10 steers per treatment on d 28 and 84 of the experiment for plasma glucose and TM concentration and volatile fatty acid analysis, respectively. On d 154 of the experiment, steers were harvested at a commercial abattoir and carcass data was collected. Data were analyzed on a pen mean basis for a randomized complete block design using PROC MIXED of SAS. There was no TM source by Cr supplementation interactions for any of the response variables measured, therefore only main effects are reported. Overall ADG (P = 0.03) and gain:feed (P = 0.02) were greater in steers receiving supplemental Cr when compared with steers not supplemented with Cr. Hot carcass weight (P = 0.04), dressing percentage (P = 0.01), longissimus muscle area (P = 0.03), and USDA yield grades (P = 0.04) were greater in steers receiving hydroxychloride TM compared with steers receiving sulfate TM. Steers supplemented with Cr had a greater dressing percentage (P = 0.01) and longissimus muscle area (P = 0.04) compared with steers not supplemented with Cr. On d 28 of the experiment, ruminal acetate concentrations were lesser (P = 0.01) and ruminal propionate concentrations tended to be greater (P = 0.12) in steers receiving hydroxychloride TM compared with steers receiving sulfate TM. Steers supplemented with Cr had greater ruminal acetate concentrations (P = 0.04) and plasma glucose concentrations (P = 0.05) on d 28 of the experiment when compared with non-supplemented controls. These data indicate the Cr supplementation and TM source can influence feedlot steer performance, carcass characteristics, and rumen fermentation characteristics.

Liquid–liquid extraction method for the gas chromatography – mass spectrometry analysis of volatile fatty acids in wastewater

ABSTRACT This study addresses the need to transition WWTPs from energy-intensive operations to carbon-neutral and energy-efficient systems by examining VFAs’ concentrations, which vary significantly with different types of wastewater. The analytical performance of the liquid–liquid extraction (LLE) method using two solvents – methyl-tert-butyl ether (MTBE) and dichloromethane (DCM) – followed by injection into a gas chromatography-mass spectrometry (GC-MS) system is evaluated. The limit of quantification (LOQ) and limit of detection (LOD) for VFAs ranged from 3 to 7.41 mg/L and 0.91 to 2.25 mg/L, respectively. Precision for lower VFAs (ethanoic (C2), propanoic (C3), 2-methyl-propanoic (iC4), butanoic (C4), methyl-butanoic (iC5), and pentanoic acids (C5)) using DCM and MTBE ranged from 1.99% to 8.64% and 1.21% to 6.68%, respectively, with accuracies of 90.35% to 107.27% and 81.55% to 105.96%, respectively. For higher VFAs (iC6, C6, and C7) using DCM, precision ranged from 18.44% to 27.06%, and accuracy ranged from 70.1% to 101.4%. In contrast, MTBE failed to detect VFAs iC6, C6, and C7. These findings underscore the importance of solvent selection in VFA analysis and its implications for optimising WWTP operations.

Organic acid preservation of cereal grains improves grain quality, growth performance, and intestinal health of post-weaned pigs

This study investigated the effect of preserving wheat and barley grains with an organic acid liquid surfactant mould inhibitor compared to conventional artificial drying and assessed its effects on the health and performance of pigs post-weaning (PW). A 2 × 2 factorial arrangement was conducted to investigate the interaction between grain preservation method (dried vs. preserved) and zinc oxide (ZnO) inclusion (yes vs. no) on growth performance, diarrhoea scores and incidence, and total tract nutrient digestibility. One hundred and ninety-two pigs (3 pigs/pen; 16 replicates/treatment) were assigned to one of four experimental diets for 35 days: (1) dried grain diet, (2) preserved grain diet, (3) dried grain diet with ZnO and (4) preserved grain diet with ZnO. Diets were formulated to contain similar levels of net energy and standardised ileal digestible lysine. On day 35 PW, 24 pigs (12 replicates/treatment) from the non-ZnO supplemented groups were euthanised and digesta was collected for coefficient of apparent ileal digestibility (CAID), gut microbial population and volatile fatty acid analysis. Stomach tissue was also collected for gene expression analysis, as well as small intestine samples for gut morphology. Notable improvements in grain quality were observed in the preserved grain, including a reduction in grain pH, mould presence, and contamination by mycotoxins, specifically deoxynivalenol in wheat and barley, and ochratoxin A and HT-2 toxin in barley. The preserved grain diet improved average daily gain (ADG; P < 0.01) and body weight (BW; P < 0.01) compared to the dried grain diet. The incorporation of ZnO increased average daily feed intake (ADFI; P < 0.01) and BW (P < 0.05) in the dried grain diet, however, ZnO did not affect ADFI (P > 0.05), and reduced ADG and BW in the preserved grain diet (P < 0.05). Pigs offered the preserved grain diet had reduced faecal scores and diarrhoea incidence compared to those offered the dried grain diet (P < 0.05). Supplementation of ZnO reduced faecal scores and diarrhoea incidence compared to non-supplemented pigs (P < 0.001). On day 35 PW, the preserved grain diet had improved CAID of nitrogen and gross energy (P < 0.05), lower levels of colonic branched-chain volatile fatty acids (P < 0.05), and beneficial shifts in gut microbial populations. Specifically, there was a reduction in ileal Streptococcus (P < 0.001) and an increased abundance of colonic Faecalibacterium (P < 0.05). In conclusion, organic acid preservation improved grain quality, benefiting post-weaned pigs through improved nutrient digestibility and gut health, thus enhancing overall growth performance PW.

Investigation into the supplementation of a ferric sillen core-linked polymer on the health and physiological performance of broiler chickens

Poultry is a ubiquitous and highly sought-after protein source valued for its accessibility, notable protein content, and lack of religious constraints. However, the demand for poultry has resulted in a surge in intensive production practices. The transition from subsistence agricultural practices to intensive food production resulted in the widespread adoption of antibiotics for both therapeutic and economic purposes. These interventions were intended to enhance meat yield, promote bird health, and enhance cost-effectiveness of production. However, this inadvertently contributed to the rise of antimicrobial resistance (AMR). Therefore, the need to explore alternative approaches to mitigate the problems associated with AMR has become increasingly pressing. In response, metal-based compounds have emerged as a promising substitute to conventional antibiotics. In this study, the effects of a water soluble metallo-antimicrobial supplement, ferric sillen core-linked polymer (FSCLP), on body weight gain, feed conversion, water intake, volatile fatty acid (VFA) production, cecal microbiome and intestinal morphology in broilers was examined. The findings of this study suggested that the addition of the FSCLP resulted in better bird performance, even during a period of heat stress. Volatile fatty acids (VFA) analysis of cecal contents indicated that there were significantly higher levels (p < 0.05) of butyric and valeric acids. Cecal microbiome analysis confirmed significantly lower abundance (p < 0.05) of Proteobacteria (e.g., E. coli) and a significantly greater abundance of VFA-producing bacteria such as Intestinimonas butyriciproducens, Blautia and Lachnospiraceae. The intestinal morphology data showed supplementation with the FSCLP at 80 ppm resulted in a significantly higher (p < 0.05) villus height of the jejunum.This study emphasises the potential of FSCLP as a feasible solution to the issues faced by AMR in chicken production, providing insights into its beneficial impacts on performance, microbial composition, and intestinal health.

15 Effects of post-MSC DDGS inclusion in gestation diets compared with other fiber sources on in vitro gas and volatile fatty acid production

Abstract In vitro fermentation has been used to characterize hindgut fermentation of fibrous ingredients fed to grower pigs. However, there is little to no work investigating hindgut fermentation of fibrous feedtuffs in gestating sows, who have greater fermentative capacity compared with grower pigs. The objective of this study was to characterize hindgut gas production and volatile fatty acids (VFA) following in vitro fermentation using fecal inoculum collected from the sows when fed either post-protein separation dried-distiller’s grains with solubles (post-MSC DDGS), soyhulls, or sugar beet pulp. Pregnant sows (n = 22; parity 0 to 1; body weigh = 190 ± 10 kg) were allocated to 1 of 6 dietary treatments in a crossover design with two collection periods (period 1 from d 40-59 of gestation and period 2 from d 60-79 of gestation) to attain at least 7 observations per treatment. Two of the six diets were practical corn-soybean meal-based gestation diets with either soyhulls (17.5% inclusion) or post-MSC DDGS (15% inclusion). The remaining four diets included a corn-basal diet and the basal diet plus 30% inclusion of post-MSC DDGS, soyhulls, or sugar beet pulp. Sows were fed experimental diets (2.2 kg/d in a single feeding) in two 20 d collection periods. For in vitro fermentation, fresh fecal samples were collected on d 16 of each collection period, prepared as inoculum, and subjected to the gas production measurement technique through in vitro fermentation. Supernatant residue from the in vitro fermentation was subjected to VFA analysis by gas chromatography. Data were analyzed with ANOVA and fixed to a mixed linear model using treatment as the main effect and collection period as a random variable. Total gas production of the practical diet containing post-MSC DDGS diet was 132 ml/g less (P = 0.03) than the practical soyhull diet. While the total concentration of total VFA did not differ between practical diets, the concentration of isovalerate tended to be greater for the post-MSC DDGS diet compared with the soyhull diet (P = 0.09). Total gas production was 140 and 375 mg/L less for the post-MSC DDGS than soyhulls and sugar beet pulp, respectively (P &amp;lt; 0.01). The concentrations of butyrate and isovalerate (relative to total VFA) were approximately 7 and 2%, respectively, greater for the post-MSC DDGS than in the soyhulls or sugar beet pulp fermentation residues (P &amp;lt; 0.05). Concentrations of other VFA relative to total VFA did not differ between fiber sources. In conclusion, post-MSC DDGS can contribute to sustainable swine production when fed to gestating by lowering total gas production and being a source of volatile fatty acids.

Temporal dynamics of volatile fatty acids profile, methane production, and prokaryotic community in an in vitro rumen fermentation system fed with maize silage.

Anaerobic in vitro fermentation is widely used to simulate rumen kinetics and study the microbiome and metabolite profiling in a controlled lab environment. However, a better understanding of the interplay between the temporal dynamics of fermentation kinetics, metabolic profiles, and microbial composition in in vitro rumen fermentation batch systems is required. To fill that knowledge gap, we conducted three in vitro rumen fermentations with maize silage as the substrate, monitoring total gas production (TGP), dry matter degradability (dDM), and methane (CH4) concentration at 6, 12, 24, 36, and 48 h in each fermentation. At each time point, we collected rumen fluid samples for microbiome analysis and volatile fatty acid (VFA) analysis. Amplicon sequencing of 16S rRNA genes (V4 region) was used to profile the prokaryotic community structure in the rumen during the fermentation process. As the fermentation time increased, dDM, TGP, VFA concentrations, CH4 concentration, and yield (mL CH4 per g DM at standard temperature and pressure (STP)) significantly increased. For the dependent variables, CH4 concentration and yield, as well as the independent variables TGP and dDM, polynomial equations were fitted. These equations explained over 85% of the data variability (R2 > 0.85) and suggest that TGP and dDM can be used as predictors to estimate CH4 production in rumen fermentation systems. Microbiome analysis revealed a dominance of Bacteroidota, Cyanobacteria, Desulfobacterota, Euryarchaeota, Fibrobacterota, Firmicutes, Patescibacteria, Proteobacteria, Spirochaetota, and Verrucomicrobiota. Significant temporal variations in Bacteroidota, Campylobacterota, Firmicutes, Proteobacteria, and Spirochaetota were detected. Estimates of alpha diversity based on species richness and the Shannon index showed no variation between fermentation time points. This study demonstrated that the in vitro fermentation characteristics of a given feed type (e.g., maize silage) can be predicted from a few parameters (CH4 concentration and yield, tVFA, acetic acid, and propionic acid) without running the actual in vitro trial if the rumen fluid is collected from similar donor cows. Although the dynamics of the rumen prokaryotes changed remarkably over time and in accordance with the fermentation kinetics, more time points between 0 and 24 h are required to provide more details about the microbial temporal dynamics at the onset of the fermentation.

Influence of vasoactive intestinal polypeptide on growth performance, nutrient digestibility, nitrogen balance, and digestive enzyme activity in lambs.

This study evaluated if vasoactive intestinal polypeptide (VIP) influences growth performance, nutrient digestibility, nitrogen balance, and digestive enzyme activity. Sixteen wether lambs (69.6 ± 1.9kg) were housed in individual pens, adapted to a corn grain-based diet, and randomly assigned to 2 treatment groups. Lambs were injected intraperitoneally every other day for 28 d with saline (0.9% NaCl) containing no VIP (n = 8; control) or containing VIP (n = 8; 1.3 nmol/kg body weight [BW]). All lambs were transferred to individual metabolic crates for the final 7 d of the experiment to measure nitrogen balance and nutrient digestibility. At the end of the treatment period, lambs were slaughtered, and pancreatic tissue, small intestinal tissue, and rumen fluid were collected for protein, digestive enzymes, ruminal pH, and volatile fatty acid (VFA) analyses. Lambs treated with VIP had greater final BW, average daily gain, and gain:feed (P = 0.01, 0.05, 0.03, respectively). No differences between treatment groups were observed (P ≥ 0.25) for nutrient intake, digestibility, nitrogen retention, ruminal pH, and VFA concentrations. Moreover, VIP treatment did not influence (P ≥ 0.19) plasma glucose, urea N, and insulin concentrations. Treatment with VIP increased (P = 0.03) relative cecum weight (g/kg BW) and decreased (P = 0.05) relative brain weight. Pancreatic and intestinal digestive enzyme activities, except for duodenal maltase (P = 0.02), were not influenced (P ≥ 0.09) by VIP treatment. These data suggest that the administration of VIP may have potential to improve average daily gain and gain:feed in lambs fed grain-based diets.

Enteric methane emission reduction potential of natural feed supplements in ewe diets.

Research into the potential use of various dietary feed supplements to reduce methane (CH4) production from ruminants has proliferated in recent years. In this study, two 8-wk long experiments were conducted with mature ewes and incorporated the use of a variety of natural dietary feed supplements offered either independently or in combination. Both experiments followed a randomized complete block design. Ewes were offered a basal diet in the form of ad libitum access to grass silage supplemented with 0.5kg concentrates/ewe/d. The entire daily dietary concentrate allocation, incorporating the respective feed supplement, was offered each morning, and this was followed by the daily silage allocation. In experiment 1, the experimental diets contained 1) no supplementation (CON), 2) Ascophyllum nodosum (SW), 3) A. nodosum extract (EX1), 4) a blend of garlic and citrus extracts (GAR), and 5) a blend of essential oils (EO). In experiment 2, the experimental diets contained 1) no supplementation (CON), 2) A. nodosum extract (EX2), 3) soya oil (SO), and 4) a combination of EX2 and SO (EXSO). Twenty ewes per treatment were individually housed during both experiments. Methane was measured using portable accumulation chambers. Rumen fluid was collected at the end of both experiments for subsequent volatile fatty acid (VFA) and ammonia analyses. Data were analyzed using mixed models ANOVA (PROC MIXED, SAS v9.4). Statistically significant differences between treatment means were considered when P < 0.05. Dry matter intake was not affected by diet in either experiment (P > 0.05). Ewes offered EO tended to have an increased feed:gain ratio relative to CON (P < 0.10) and SO tended to increase the average daily gain (P < 0.10) which resulted in animals having a higher final body weight (P < 0.05) than CON. Ewes offered EX1 and SO emitted 9% less CH4 g/d than CON. The only dietary treatment to have an effect on rumen fermentation variables relative to CON was SW, which enhanced total VFA production (P < 0.05). In conclusion, the A. nodosum extract had inconsistent results on CH4 emissions whereby EX1 reduced CH4 g/d while EX2 had no mitigating effect on CH4 production, likely due to the differences in PT content reported for EX1 and EX2. SO was the only dietary feed supplement assessed in the current study that enhanced animal performance whilst mitigating daily CH4 production.

Influence of Fermentation Time and Inoculation of Starter Culture on the Chemical Composition of Fermented Natural Coffee Followed by Depulping.

Fermentation using starter cultures has been considered an alternative and economically viable technology for the production of specialty coffees. This type of technology promotes several benefits, such as increased sensory quality, control over the fermentation process, predictability of the final product and added value. Coffee (Coffea arabica L.) samples for this study were collected in Presidente Olegário - MG (2018/19 crop year) in the Cerrado region of Minas Gerais. The effects of natural fermentation and inoculation of the yeast Torulaspora delbrueckii and duration of fermentation (0, 24, 48, 72 and 96 hours) on the sensory and chemical quality (analysis of bioactive, volatile, and organic compounds and fatty acids) of coffee were evaluated. The objective of this study was to determine the effect of fermentation time and starter culture inoculation on the chemical composition of fermented coffees. Fermentation time significantly influenced the sensory description of the coffee beverage, with notes of honey, brown sugar and almond predominating up to 48 hours, for coffees fermented for 72 and 96 hours the notes described were and fruity, winey notes. The chemical composition was primarily influenced by fermentation time.

Synergistic Impacts of Wheat Straw on Coal Bio‐Methanation: Insights Into Microbial Community Dynamics Toward Nontargeted Metabolomics

Biogenic methane (BM) production from coal is quite limited due to its complex chemical nature, which makes the responsible microbes sensitive to its denaturation. In the current investigation, wheat straw (WS) at different concentrations as a cosubstrate were used with coal to augment methane generation from coal. Results revealed that the codigestion approach significantly enhanced the cumulative methane generation in CS1 (17.25 mmol) (coal:straw, 75:25), which was 59.52%–256.47% higher than the CS2 (coal:straw, 85:15), and WS single digestion, respectively. Moreover, the lowest methane yield (0.295 mmol/g) was achieved from single coal digestion. Particularly, the highest methane content, 68.37% in the collected biogas, was observed in CS1, followed by CS2 (49.53%), WS (44.92%), and coal (3.53%). Microbial community analysis illustrates that Methanobacteriaceae (51.33%) and Methanosarcinaceae (48.66%) were the leading archaeal communities at the peak methanogenic stage in CS1. While the abundant bacteria at this stage were Hungateiclostridiaceae (40.18%), Rhodobacteriaceae (21.40%), and Lentimicrobiaceae (19.20%) in CS1. According to scanning electron microscopy (SEM) analysis, several microbes were seen to be attached to the coal surface in CS1 and CS2. Moreover, the nontargeted metabolomic results showed that aromatics, aliphatic, long‐chain fatty acids, and alkane (C19–C36) compounds were found to be highly expressed in only coal, CS1, and CS2 reactors compared to WS. In addition, volatile fatty acids (VFAs) analysis showed that acetic acids were abundantly present in CS1 (2,190,175 ng/ml), followed by WS (1,543,492.88 ng/ml), CS2 (1,159,050 ng/ml), and coal (50,998.31 ng/ml). These results promote the significance of using WS as a cosubstrate with coal to enhance methane production, which can be used as a fuel in power plants. Further studies are required to investigate the potential cosubstrate with coal to enhance methane production and identify the specific metabolic pathways involved.

Effects of Rumen Fermentation Characteristics on Stress-Related Hormones and Behavior in Sheep

This study investigated the relationship between rumen fermentation, stress-related hormones, and behavior in sheep with the aim of providing insights for improving animal welfare and feed management practices. Eight lambs were assigned to either a high concentration or control group. Blood samples were collected for hormone analysis, and an open field test was conducted to observe behavioral stress responses. The results showed that diet composition may affect the behavior of ruminants in response to stressors and novel situations, as evidenced by the higher number of escape attempts in the high-concentration group. In addition, analyses of individual volatile fatty acids (VFAs) showed a significant positive correlation between the acetic acid/propionic acid ratio and sniffing behavior of the novel object (p &lt; 0.05, ρ = −0.414). These findings have important implications for animal welfare and feed management practices. Overall, this study provides insights into the potential impact of diet composition on the behavior of ruminants in response to stressors and novel situations, highlighting the importance of improving animal welfare through feed management practices. Further research is needed to fully elucidate the mechanisms underlying the complex relationship between rumen fermentation, stress-related hormones, and behavior in ruminant animals.

EXPLORANDO ADITIVOS PARA MEJORAR LA PRODUCCIÓN FERMENTATIVA DE BIOHIDRÓGENO

Dark fermentation appears as a promising strategy in the new energy landscape, as it enables the production of biohydrogen using a wide range of biomass substrates, thus also contributing to waste management. However, this process exhibits lower yields compared to conventional thermochemical processes for H2 production, such as reforming. To overcome this limitation, the use of additives has been explored to enhance microbial activity and increase dark fermentation yields. However, the application of additives remains limited in practice. This study aims to address this gap by examining the effects of three types of additives (zero-valent iron, activated carbon, and hydrochar) on dark fermentation and hydrogen generation. The results reveal that hydrochar shows the most promising outcomes, increasing H2 production by 20.3%, with the highest biohydrogen yield at 92 mLH2/g-glucose. Volatile fatty acid analysis reveals that butyric and acetic pathways are utilized for H2 production in this case. It is also important to consider the alkalinity of the feedstock, as high levels can increase the pH in the medium and promote methane (CH4) production as the main fermentation product instead of H2. When this occurs, Fe(0) NPs appear to be the additive that most favors methane generation, resulting in a 6.1% higher production compared to the control experiment. This confirms the interest in the use of certain additives in fermentative processes. Keywords: Activated carbon, Addition, Dark fermentation, Fe(0) nanoparticles, Green hydrogen, Hydrochar, VFA.

Acceleration of the startup process of an anaerobic baffled reactor utilizing electrolyte regeneration

The objective of this study was to examine the performance of an electrolytic anaerobic baffled reactor (EABR) that contained five rectangular compartments in the treatment of low-strength synthetic wastewater. The effect of integration of electrolysis into an anaerobic baffled reactor (ABR) on the startup process, removal of chemical oxygen demand (COD), production of volatile fatty acids (VFAs), and profile of the pH of the EABR were investigated. With a low-strength influent (COD = 600 mg/L), the results indicated that COD removal was 92 % and that the VFAs were negligible by the third compartment. Also, VFA analysis showed that propionic acid was found in the first two compartments. This finding is aligned with compartment-wise profiles of COD removal, which was the highest in the initial compartments and which decreased longitudinally down the reactor. Monitoring the pH profile elucidated that the largest drop in pH was observed in the first two compartments, which is attributed to acidogenesis and acetogenesis activities. The proposed integration could decrease the startup process time to 12 d or less for low-strength feed of synthetic wastewater. This study demonstrated the significance of maintaining a stable pH for the optimal functioning of a diverse bacterial community by integrating bioelectrochemical processing in anaerobic digestion, as well as the application of the potential strategies to optimize the startup process of ABR. The optimization of the startup process of ABR through the integration of bioelectrochemical processing can contribute to Sustainable Development Goal 9 (Industry, Innovation, and Infrastructure) by promoting sustainable technological advancements and fostering sustainable industrialization.

The Effect of a Bacillus Probiotic and Essential Oils Compared to an Ionophore on the Rumen Microbiome Composition of Feedlot Cattle.

The rising concern of antibiotic growth promoter use in livestock has necessitated the investigation into alternative feed additives. The effect of a probiotic and essential oils to an ionophore on the rumen microbiome composition of Bonsmara bulls raised under feedlot conditions was compared. Forty-eight Bonsmara weaners were allocated to four groups: a group with basal diet (CON) and three groups supplemented with monensin (MON), probiotic (PRO), and essential oils (EO). During the 120 days feeding period, rumen content was collected from four animals per group within each phase via a stomach tube for 16S rRNA and internal transcribed spacer (ITS) sequencing as well as volatile fatty acid analysis. In the starter phase, MON had a significantly lower acetate to propionate ratio and a higher Succinivibrionaceae abundance. The abundance of Lachnospiraceae was significantly higher in EO compared to MON. In the finisher phase, PRO had a significantly higher bacterial diversity. The alpha diversity did not differ between the fungal populations of the groups. The abundance of Proteobacteria was the lowest in PRO compared to the other groups. Limited variation was observed between the rumen microbiome composition of monensin compared to the other treatment groups, indicating that these alternatives can be considered.

Changes and correlation analysis of volatile compounds, key enzymes, and fatty acids in lemon flavedo under different drying methods

Lemon flavedo is distinguished by their unique and abundant volatile flavor compounds that can undergo complex changes during drying. In this study, integrated freeze drying (IFD), conventional freeze drying (CFD), and hot-air drying (AD) were employed to dry lemon flavedo to investigate the changes and correlations of volatile compounds, fatty acids, and key enzymatic activities during the drying process. The results showed that IFD retained the most volatile compound types, followed by CFD and AD. Furthermore, after drying, IFD, CFD, and AD had lost 47.92 mg/g, 56.07 mg/g, and 13.22 mg/g of total volatile compounds, respectively, compared with fresh samples, and the content loss rates of total fatty acids were 77.38% in AD > 72.95% in CFD > 56.54% in IFD, respectively. During the three drying processes, IFD retained relatively higher enzyme activity in the samples. Lots of positive and negative correlations (P < 0.05) were observed among the key enzyme activities, fatty acids, and volatile compounds, showing close associations. The current work provides important information for selecting suitable drying techniques of lemon flavedo and shows lights on how to control its flavor during drying process.

Rumen fermentation and forage degradability in dairy cows offered perennial ryegrass, perennial ryegrass and white clover, or a multispecies forage

An experiment was conducted to compare the rumen fermentation and degradability of three forage treatments. A perennial ryegrass (PRG; Lolium perenne), perennial ryegrass and white clover (Trifolium pratense) (PRGWC) and multispecies forage (MULTI), containing two grass species; perennial ryegrass and timothy (Phleum pratense); two clover species; white clover and red clover (Trifolium repens); and two herb species; chicory (Cichorium intybus) and plantain (Plantago lanceolata), were compared. Six rumen fistulated lactating dairy cows were used in a replicated 3 × 3 Latin square experiment consisting of 3 periods lasting 21-days. Cows were allowed ad libitum access to fresh forage and offered 2.71 kg DM concentrate each day. During days 1 – 14 of each period, cows were acclimatized to dietary treatments before entering a 7 – day sampling period. Indwelling rumen pH probes were inserted into the rumen of each cow on day 15 and 16. Rumen fluid samples were taken on day 18 every 2 h for rumen volatile fatty acid and ammonia nitrogen (NH3N) analysis. Forage dry matter (DM) and crude protein (CP) degradability was assessed via in sacco incubation beginning on day 19 of each period. Treatment had no effect on dry matter intake (DMI) or milk yield. There was no difference in mean rumen pH between treatments. The rumen pH of cows offered MULTI was below pH 6.0 for a higher percentage of time than the other treatments, however the concentration of acetic acid in the rumen of cows was similar between treatments. Effective degradability (ED) of DM was higher (P = 0.003) for MULTI (0.77) compared to PRG (0.68) and PRGWC (0.66). The soluble CP fraction of MULTI and PRGWC was significantly lower than that of PRG (P = 0.007), though PRGWC had the highest rumen ammonia concentration of all treatments (P = 0.002). MULTI had the highest ED and rate of DM degradation in the rumen, and lowest soluble CP of all treatments. Multispecies forages can support milk production in lactating dairy cows; however, care must be taken to ensure adequate dietary NDF due to the low fiber concentration and highly degradable nature of the forage.

3-Nitrooxypropanol supplementation of a forage diet decreased enteric methane emissions from beef cattle without affecting feed intake and apparent total-tract digestibility.

Supplementation of ruminant diets with the methane (CH4) inhibitor 3-nitrooxypropanol (3-NOP; DSM Nutritional Products, Switzerland) is a promising greenhouse gas mitigation strategy. However, most studies have used high grain or mixed forage-concentrate diets. The objective of this study was to evaluate the effects of supplementing a high-forage diet (90% forage DM basis) with 3-NOP on dry matter (DM) intake, rumen fermentation and microbial community, salivary secretion, enteric gas emissions, and apparent total-tract nutrient digestibility. Eight ruminally cannulated beef heifers (average initial body weight (BW) ± SD, 515 ± 40.5 kg) were randomly allocated to two treatments in a crossover design with 49-d periods. Dietary treatments were: 1) control (no 3-NOP supplementation); and 2) 3-NOP (control + 150 mg 3-NOP/kg DM). After a 16-d diet adaption, DM intake was recorded daily. Rumen contents were collected on days 17 and 28 for volatile fatty acid (VFA) analysis, whereas ruminal pH was continuously monitored from days 20 to 28. Eating and resting saliva production were measured on days 20 and 31, respectively. Diet digestibility was measured on days 38-42 by the total collection of feces, while enteric gas emissions were measured in chambers on days 46-49. Data were analyzed using the mixed procedure of SAS. Dry matter intake and apparent total-tract digestibility of nutrients (DM, neutral and acid detergent fiber, starch, and crude protein) were similar between treatments (P ≥ 0.15). No effect was observed on eating and resting saliva production. Relative abundance of the predominant bacterial taxa and rumen methanogen community was not affected by 3-NOP supplementation but rather by rumen digesta phase and sampling hour (P ≤ 0.01). Total VFA concentration was lower (P = 0.004) following 3-NOP supplementation. Furthermore, the reduction in acetate and increase in propionate molar proportions for 3-NOP lowered (P < 0.001) the acetate to propionate ratio by 18.9% as compared with control (4.1). Mean pH was 0.21 units lower (P < 0.001) for control than 3-NOP (6.43). Furthermore, CH4 emission (g/d) and yield (g/kg DMI) were 22.4 and 22.0% smaller (P < 0.001), respectively, for 3-NOP relative to control. Overall, the results indicate that enteric CH4 emissions were decreased by more than 20% with 3-NOP supplementation of a forage diet without affecting DM intake, predominant rumen microbial community, and apparent total-tract nutrients digestibility.

Evaluation of growth, meat quality, and sensory characteristics of wool, hair, and composite lambs.

The objectives of this study were to evaluate the growth rates, carcass quality, shelf-life, tenderness, sensory characteristics, volatile compounds, and fatty acid composition of wool, hair, and composite (wool × hair) lambs. Twenty-one wether lambs [wool (Suffolk × Polypay/Targhee; n = 7), hair (Dorper × Dorper; n = 7), and composite (Dorper × Polypay/Targhee; n = 7)] were fed from weaning to finishing at the University of Idaho Sheep Center and subsequently harvested under United States Department of Agriculture inspection at the University of Idaho Meat Lab. At 48 h postmortem, carcass measurements were taken to determine the percent boneless closely trimmed retail cuts, yield grade, and quality grade. Loins were fabricated from each carcass and wet-aged at 0°C until 10-d postmortem. Following aging, 2.54-cm bone-in loin chops were cut and randomly assigned to 4 d of retail display, Warner-Bratzler Shear Force (WBSF), or sensory analyses. Thiobarbituric acid reactive substances were analyzed on days 0 and 4 of retail display while subjective and objective color measurements were observed once daily. Samples (24 g) were also collected for volatile compound and fatty acid analysis. A mixed model analysis of variance was used to assess breed differences. Discernable effects were considered at P < 0.05. Wool lambs had heavier hot carcass weights (P < 0.001), larger rib-eye area (P = 0.015), and higher dressing percent (P < 0.001) than the other breeds. There was an interaction observed between breed and days of retail display for browning (P = 0.006). On day 1 chops from the composite breed had more browning than chops from the wool breed. No differences were observed between groups for lean muscle L* values (P = 0.432), a* values (P = 0.757), and b* values (P = 0.615). Differences were not observed in lipid oxidation (P = 0.159), WBSF (P = 0.540), or consumer acceptability (P = 0.295). There were differences found for 7 of the 45 fatty acids detected and in 3 of the 67 volatile compounds detected. In conclusion, wool lambs were heavier and had a greater carcass yield than the hair lamb carcasses. Regardless of breed, consumers did not detect sensory traits that would impact their eating experience.