Volatile Fatty Acid Concentrations Research Articles

476 Induced hindgut acidosis in sheep affected gut permeability and ruminal fermentation

Abstract Leaky gut may be caused by acidotic conditions in the hindgut and lead to systemic inflammation and negative effects on the gastrointestinal tract. The objective was to determine the effects of induced hindgut acidosis in sheep on cecal pH, ruminal fermentation, and gut permeability. Ruminally and cecally cannulated ewes [n = 11; body weight (BW) = 49 ± 4 kg] were assigned to one of two treatments: control (CON; n = 5) or induced hindgut acidosis (HGA; n = 6). To induce hindgut acidosis, 3 g wheat starch/kg BW per 24 h was continuously infused via the cecal cannula for 4 d. Control ewes received a constant infusion of deionized water. The diet contained 40% grass hay pellets, 35% whole shelled corn, 15% dried distillers grains, and 10% alfalfa cubes. Chromium EDTA was dosed once daily via the cecal cannula as a marker of gut permeability. Rumen, cecal, and fecal samples were collected to determine pH and volatile fatty acids (VFA). Rumen fluid was collected on d 4 for an ex vivo fermentation. Flasks were incubated for 24 h to determine pH, VFA, ammonia and in vitro dry matter digestibility. Tissue samples from the ileum, cecum, and colon were mounted in Ussing chambers to measure transepithelial electrical resistance (TEER). There was a treatment × time effect (P = 0.05) for cecal pH with HGA ewes having lesser cecal pH after d 1. By d 4, cecal pH had declined to 5.07 for HGA ewes compared with CON ewes which remained above 6.40 throughout the experiment. A treatment × time interaction was also observed (P < 0.01) for fecal pH and followed the same trend as cecal pH. Rumen pH was not affected (P = 0.87) by the interaction of treatment and time but was affected (P < 0.01) by treatment as ewes on the HGA treatment had a lesser rumen pH than CON ewes. Control ewes had lesser ruminal VFA and ammonia concentrations than HGA ewes (P < 0.01). Urinary Cr recovery was not affected by the interaction of treatment and time, or treatment (P ≥ 0.13). In vitro dry matter disappearance was not affected by cecal infusion treatment (P = 0.60). There was no effect (P = 0.78) of treatment on ex vivo pH. There were no effects (P ≥ 0.11) of treatment, time, or their interaction on ex vivo ammonia or total VFA concentration. In cecal tissue, TEER tended (P = 0.09) to be greater in CON ewes than HGA ewes. In contrast, TEER was not different (P ≥ 0.83) in ileal or colonic tissues between treatments. Induced hindgut acidosis in sheep altered rumen fermentation and tended to increase ex vivo measures of cecal permeability, but did not affect ex vivo rumen fermentation.

248 Impacts of sprouted barley on the performance and carcass traits in finishing Angus steers

Abstract The growing population, coupled with unpredictable weather patterns, demands that livestock producers think innovatively to improve sustainability. Producers are interested in innovative practices and technology, such as controlled environment farming to sprout cereal grains that can be fed to livestock. However, little research has determined the effects of giving these feeds to finishing beef steers. As such, Angus steers (n = 60) were stratified by body weight (BW; 385 kg ± 10.3) to receive two different diets (n = 30/diet). The control (CON) diet was a traditional finishing ration for the region, whereas the other included 20% (dry matter; DM) sprouted barley (SB) in place of corn silage. Animals were fed for 128 d in pens with Vytelle units to measure intake and feeding behavior. On d 0, 30, 60, 90, and 128 BW, ruminal fluid, and ultrasound measurements were taken. Liver score (LS) and typical carcass data were collected from a commercial harvest facility. Statistical analyses used the MIXED procedure of SAS to assess the main effect of diet for all measurements collected over time. Dry matter intake (DMI), feed efficiency (gain to feed; G:F), ruminal volatile fatty acid (VFA) composition, and feeding behavior were run as repeated measures. No differences (P = 0.37) in BW gain were found between steers receiving different diets, but steers receiving SB had decreased (P < 0.0001) DMI throughout the trial compared with CON. This decrease in DMI drove a diet × day effect (P = 0.004) for G:F such that SB had increased (P ≤ 0.04) G:F on d 0 and 60, but no effect (P ≥ 0.52) was observed at d 90 or 128. Steers receiving the CON diet spent more (P < 0.0001) time at the feed bunk than those receiving the SB diet, which supports the observation that steers receiving the CON had an increased DMI. Ruminal pH, total VFA concentration, acetate:propionate, percent propionate, and percent butyrate were each impacted by diet × day (P ≤ 0.007). The only carcass trait impacted by diet was yield grade (YG), where steers receiving the SB diet had an increased (P < 0.03) YG compared with CON. These results demonstrate that replacing corn silage with SB in the ration of finishing steers has some effect on ruminal VFA composition, DMI, G:F, and USDAYG. Due to decreased DMI, SB steers had increased feed efficiency which could potentially have a positive economic impact for producers. However, additional analysis is needed to further determine if these systems are economically viable in a production setting.

191 Awardee Talk: Characterizing biological processes influencing the efficiency of nutrient utilization in growing cattle

Abstract 2Abstract: Residual feed intake (RFI), a metric of feed efficiency, is moderately heritable and minimally associated with body size and productivity, making it an ideal trait for investigation as a selection criterion to improve feed efficiency of growing cattle. The objective of this research was to characterize the inter-animal variation in biological processes of growing cattle selected to be divergent in RFI. Holstein heifers [n = 55; body weight (BW) = 351 ± 64 kg) with low- (n = 29) or high- (n = 26) genomically enhanced RFI (RFIg) were selected from a contemporary group of 453 heifers. Heifers were assigned to 1 of 2 pens, equipped with electronic feed bunks and a GreenFeed gaseous-exchange measurement system. Individual dry matter intake (DMI) and feeding behavior data were collected for 84-d. Body weight was measured weekly, and spot fecal samples collected at weighing. Phenotypic RFI (RFIp) was calculated as the residual from regression of DMI on ADG and mid-test BW0.75. On d 70 of the study a rumen fluid sample was collected via esophageal tubing. Blood samples were collected and analyzed for complete blood count (CBC). A mixed model including the fixed effect of RFIg classification and random effect of pen was used to evaluate the effect of RFIg classification on response variables. There were no differences (P > 0.05) in BW and ADG for heifers with divergent RFIg; however, low RFIg heifers consumed 7.5% less (P < 0.05) feed per day. Consequently, low RFIg heifers exhibited a more favorable (P < 0.05) RFIp (-0.188 vs 0.211 kg/d, respectively). Low RFIg heifers exhibited more favorable feeding behavior, with 8.7% fewer (P < 0.05) bunk visit events per day and an 11.2% slower (P ≤ 0.05) eating rate. Low RFIg heifers had 12.5% greater (P < 0.05) total rumen volatile fatty acid concentrations than high RFIg heifers, indicating potentially enhanced microbial fermentation and improved efficiency of feed utilization. Low RFIg heifers had 8.2% less (P < 0.05) methane emissions (g/d), 6.3% less (P < 0.05) carbon dioxide production (g/d), and 6.1% less (P < 0.05) heat production (Mcal/d) calculated according to Brouwer (1965) than high RFIg heifers. Dry matter digestibility did not differ (P > 0.05) between heifers with divergent RFIg. Overall, heifers selected to be more feed efficient exhibited more favorable energy efficiencies and feed efficiency phenotypes. To quantify the variation in RFIg explained by feeding behavior, gas flux, digestibility and rumen fermentation, and CBC partial least squares regression models were developed. Feeding behavior accounted for the largest proportion of variation in RFIg (28.8%). Upon sequential addition of gas flux, digestibility and rumen fermentation, and CBC to feeding behavior, 56.3% of the variation in RFIg was accounted for. Identifying the magnitude at which metabolic processes influence inter-animal variation in efficiency of nutrient utilization provides opportunities to discover valuable candidate biomarkers for selection of more feed efficient cattle.

Effects of Partial Replacement of Corn Grains With Mango Seed Kernel on Nutrient Digestibility, Blood Metabolites and Rumen Parameters of Growing Calves.

Fruit by-products are a sustainable and cost-effective alternative to traditional grain feed for livestock. One of the most important by-products is mango seed kernel (MSK), which can be used as a valuable energy source for feeding growing calves in the tropical and subtropical productive regions of the world. This study investigated the effect of replacing corn grains (CGs) with MSK on intake, nutrient digestibility, blood metabolites and rumen parameters. Eighteen growing male Friesian calves (200 ± 6.55 kg of body weight and 9-11 months old) were randomly assigned to three treatment groups. Three concentrate feed mixtures were formulated such that MSK replaced CG at 0%, 25% and 50%. Dry matter intake was unaffected, whereas dry matter, organic matter and fibre digestibility increased linearly (p < 0.05) with increased inclusion of MSK. Ruminal pH (p = 0.053) and total volatile fatty acid (VFA) concentration (p = 0.041) increased linearly. There was a linear decrease in cholesterol (p = 0.029) and AST (p = 0.028) levels in the blood of calves. In conclusion, this study demonstrated the positive effect of replacing 50% of CG with MSK on rumen parameters, including a higher ruminal pH and total VFA concentration, alongside higher nutrient digestibility. The dietary inclusion of mango seed can serve as a valuable and sustainable dietary component for growing calves.

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

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

Metagenomic insights into the mechanistic differences of plant polyphenols and nitrocompounds in reducing methane emissions using the rumen simulation technique

Methane (CH4) emissions from ruminants contribute significantly to greenhouse gas levels and also result in considerable feed energy losses. Plant polyphenols and nitrocompounds are two typical types of methane inhibitors. The study investigates the mechanistic differences between 2-nitroethanol (NE) and proanthocyanidins (PAC) in reducing methane emissions from ruminant livestock using the rumen simulation technique (RUSITEC) combined with metagenomic analyses.The experiment was performed as a complete randomized block design with 3 runs. Run was used as a blocking factor. The treatments included a control (CON) with no additive, NE at 0.5 g/kg dry matter (DM), and PAC at 20 g/kg DM, all incubated in vitro for 24 h (h) with eight replicates per treatment. The results showed that NE significantly reduced CH4 production by 94.9 % (P < 0.01) and total volatile fatty acid (TVFA) concentration by 11.1 % (P < 0.05) compared to the control. NE also decreased the acetate-to-propionate ratio (A/P) from 1.93 to 1.60 (P < 0.01), indicating a shift towards more efficient fermentation. In contrast, PAC reduced methane production by 11.7 % (P < 0.05) and decreased the A/P (P < 0.05) while maintaining microbial diversity and fermentation stability, with no significant impact on TVFA concentration (P > 0.05). Metagenomic analysis revealed that NE markedly suppressed the abundance of key genera involved in carbohydrate metabolism, including Prevotella and Bacteroides, leading to reduced acetate and butyrate pathways. NE also selectively inhibited methanogenic archaea, particularly Methanobrevibacter spp., which are integral to the hydrogenotrophic pathway (P < 0.01). On the other hand, PAC showed selective inhibition of Methanosphaera spp., targeting the methylotrophic pathway (P < 0.01). These findings provide valuable insights into the distinct microbial and metabolic pathways modulated by NE and PAC, offering potential strategies for developing effective dietary interventions to mitigate methane emissions in ruminant livestock.

Volatile fatty acids (VFAs) production from sludge and chicken manure anaerobic co-fermentation: Effects of mixing ratio and microbial mechanisms

Aimed at exploring the effects of co-fermentation with different dewatered sludge (DS) and chicken manure (CM) ratios on volatile fatty acid (VFA) production, five experimental groups with different DS/CM ratios were set up, the microbial community and the activity of functional enzymes were discussed in this study. The highest concentration of VFAs reached 153.74 mgCOD/gVSS at the ratio of 1:3, and dominated by acetic and propionic acids, which was 1.37 times higher than the control group. The addition of CM contributed to the accumulation of soluble chemical oxygen demand (sCOD) and promoted the release of NH4+-N and PO43--P. High-throughput sequencing results indicated that co-fermentation enriched hydrolytic and acidogenic bacteria to promote the hydrolysis and acidification processes and facilitated the accumulation of VFAs. Firmicutes were the dominant phylum in all experimental groups, and 1:3 ratio was more satisfied with acidogenic bacteria (such as Bacillus and Clostridium_sensu_stricto_1). Meanwhile, the abundances of glycolysis/gluconeogenesis, amino sugar, and nucleotide sugar metabolisms exceeded other groups. Furthermore, this condition exhibited the highest abundances of acetyltransferase [EC: 2.3.1.8] and acetate kinase [EC: 2.7.2.1], which were 2.71 and 1.66 times higher than that in the control group, respectively.

Effects of Storage Time and Temperature on the Fermentation Characteristics of Rumen Fluid from a High-Forage Diet

The objective of this experiment was to investigate the effects of storage temperature and preservation time on the fermentation characteristics of rumen fluid collected from six Hu sheep fed a high-forage diet. The storage temperatures were set at −80 °C and −20 °C, and the preservation times were labelled as follows: 0 d (fresh rumen fluid, D0), 7 d (D7), 14 d (D14), 30 d (D30), 60 d (D60), 120 d (D120), and 240 d (D240). A repeated-measures design was applied to analyze the fermentation characteristics of rumen fluid across each preservation time point and storage temperature. The results showed that storage temperature had no significant effects on pH value, ammonia nitrogen (NH3-N), microbial protein (MCP), and volatile fatty acid (VFA) concentration and proportion (p &gt; 0.05). Specifically, the pH value increased on D7, D14, and D60 (p &lt; 0.05), while the MCP concentration decreased on D7, D14, D30, D120, and D240 but increased on D60 (p &lt; 0.05), and the concentration of NH3-N decreased on D14 (p &lt; 0.05). The acetate concentration increased on D30, while the concentrations of propionate, butyrate, valerate, and total VFA increased on D60 (p &lt; 0.05). The concentration of isovalerate decreased on D60, and isobutyrate and branched-chain VFA concentrations decreased on D120 (p &lt; 0.05). The proportion of acetate increased on D30, while the butyrate and valerate proportions increased on D60, and the proportions of isovalerate, isobutyrate, and branched-chain VFA decreased on D60 (p &lt; 0.05). For rumen fluid from a high-forage diet, the storage temperature (−80 °C and −20 °C) did not affect its fermentation characteristics, suggesting that rumen fluid could be preserved at −80 °C or −20 °C without altering its fermentation characteristics. The fermentation parameters of rumen fluid changed significantly after 7 days of preservation; hence, it is recommended to finish determining the fermentation parameters of rumen fluid within 7 days of collection. The concentrations and proportions of most VFA changed after 30 days of preservation; therefore, it is recommended that VFA determination should be completed within 30 days of rumen fluid collection.

Effects of High-Grain Diet on Performance, Ruminal Fermentation, and Rumen Microbial Flora of Lactating Holstein Dairy Cows.

The objectives of the current study were to evaluate the fluctuations in production performance, rumen fermentation, and microbial community in lactating dairy cows fed a high-grain diet (HG). In this study, 16 healthy Holstein lactating dairy cattle with similar milk yields of 16.80 ± 4.30 kg/d, days in milk 171.44 ± 23.25 days, and parity 2.2 ± 1.5 times were selected and randomly allocated into two groups. One group was fed a low-grain diet (LG; 40% concentrate, DM basis; n = 8), and the other group was fed a high-grain diet (HG; 60% concentrate, DM basis; n = 8). The experiment lasted 6 weeks, including 1 week for adaptation. The experimental results showed that the milk fat content in the milk of lactating cows in the HG group was significantly reduced (p < 0.05), and the milk urea nitrogen (MUN) content showed an increasing trend (0.05 < p < 0.10) compared with the LG group. Compared with the LG group, rumen fluid pH was significantly decreased after feeding a high-grain diet, and contents of total volatile fatty acids (TVFA), acetate, propionate, and butyrate were significantly increased (p < 0.05). The acetate/propionate significantly decreased (p < 0.05). HG group significantly increased the abundance of Prevotella and Bacteroides in rumen fluid while significantly reducing the abundance of Methanobrevibacter and Lachnospiraceae ND3007_group (p < 0.05). Microorganisms with LDA scores > 2 were defined as unique, with the bacterial genus Anaerorhabdus_furcosa_group identified as a biomarker for the LG group, and the unique bacterial genus in the HG group were Prevotella, Stenotrophomonas, and Xanthomonadaceae. The prediction results of microbial function showed that a total of 18 KEGG differential pathways were generated between the two treatment groups, mainly manifested in metabolic pathways, signal transduction, and the immune system. In conclusion, the HG group promoted rumen fermentation by altering the microbial composition of lactating cows. Our findings provide a theoretical basis for the rational use of high-grain diets to achieve high yields in intensive dairy farming.

Combination of Phytoactives in the Diet of Lactating Jersey Cows: Effects on Productive Efficiency, Milk Composition and Quality, Ruminal Environment, and Animal Health.

This study's objective was to evaluate whether adding a combination of phytoactive (microencapsulated essential oils, minerals, turmeric extract, tannin, prebiotic, and probiotic) to the feed of lactating Jersey cows positively affects the production, composition, and quality of milk, rumen environment, and animal health. Fourteen Jersey cows were divided into two groups (control and phytogenic) for an experiment with two lactation phases of 45 days each (early lactation and mid-lactation). During the experiment, milk production was higher at various times in cows that consumed phytoactive, and these animals had the best feed efficiency. In mid-lactation, phytoactive intake increased nutrient digestibility. The number of lymphocytes in the blood is reduced when cows consume phytoactive substances. Globulin levels increased in these cows fed with the additive, which may be related to a higher concentration of immunoglobulins, especially IgA. Cows fed phytoactives had lower ceruloplasmin and haptoglobin concentrations. Lower serum lipid peroxidation, associated with greater glutathione S-transferase activity, is a good health indicator in cows that consume phytoactive substances. The higher concentration of volatile fatty acids was due to the higher proportion of acetic acid in the ruminal fluid combined with lower butyric acid. Somatic cell counts in milk were lower in cows that consumed phytoactives during mid-lactation, as well as the effect of the treatment on Streptococcus spp. (lower in cows that consumed the additive). We conclude that consuming the additive benefits cows' health modulates rumen fermentation and nutrient digestibility, and positively affects milk production and quality.

Statistical modeling and optimization of volatile fatty acids production by anaerobic digestion of municipal wastewater sludge.

Obtaining value-added products from renewable resources is limited by the lack of specific operating conditions optimized for the physico-chemical characteristics of the biomass and the desired end product. A mathematical model and statistical optimization were developed for the production of volatile fatty acids (VFAs) by anaerobic digestion of municipal sewage sludge. The experimental tests were carried out in triplicate and investigated a wide range of conditions: pH 9.5, 10.5, and 11.5; temperatures 25°C, 35°C, 45°C, and 55°C; primary sludge with organic loading (OL) of 10 and 14g VS (volatile solids); and digested sludge with 4 and 6g VS. Subsequently, a statistical search was performed to obtain optimal production conditions, then a statistical model of VFA production was developed and the optimal conditions were validated at pilot plant scale. The maximum VFA concentration predicted was 6975mg COD (chemical oxygen demand)/L using primary sludge at 25°C, initial OL of 14g VS, and pH 10.5. The obtained third-degree model (r2 = 0.83) is a powerful tool for bioprocess scale-up, offering a promising avenue for sustainable waste management and biorefinery development.

Assessing the effects of high-carvacrol oregano oil on rumen microbial fermentation, gas production, and methane production in vitro

The objective of this in vitro study was to assess the effects of high-carvacrol oregano oil (ORE; 50 g/kg oregano oil, 800-802 g/kg carvacrol), on microbial fermentation and CH4 production. In the experiment (a complete randomized block design), treatments included a negative control (CTL, no additive), a positive control (monensin, MON, 10 mg/L), and ORE (20, 40, 80, 120, 200, 160, and 1000 mg/L). Compared with CTL, MON shifted (p &lt; 0.05) volatile fatty acid (VFA) profile from acetate and butyrate to propionate production, thereby reducing (p &lt; 0.05) CH4 production (-26%). Monensin decreased (p &lt; 0.05) NH3 and branched-chain VFA concentrations. Of the doses evaluated, only the highest dose (1000 mg/L) affected ruminal microbial fermentation and CH4 production. At this dose, ORE reduced (p &lt; 0.05) gas production, total VFA, acetate, propionate and NH3 concentrations, and CH4 production (-22%). The reduced gas production and total VFA is an indication of feed digestion inhibition. These results suggest that ORE may decrease CH4 production and improve ruminal N utilization. However, these findings need to be validated in vivo to determine the optimal dose to benefit from the positive effects while avoiding the negative impact of ORE on feed digestion.

Effect of exogenous cellulase pretreatment of straw-type fermented total mixed ration on digestibility and ruminal fermentation in growing beef cattle.

This study aimed to assess the impact of corn straw-based unfermented and fermented total mixed rations (TMR) supplemented with exogenous cellulase on the in vitro fermentation characteristics, growth performance, feeding behavior, apparent digestibility, rumen fermentation and digestive enzyme activities of Chinese Simmental bulls. Unfermented (direct spraying of exogenous cellulase onto TMR, TMR) and fermented (exogenous cellulase fermentation for more than 7 d, fermented total mixed rations [FTMR]) TMR were collected, dried, powdered and used as fermentation substrates. The fermentation liquid was ruminal fluid collected from Chinese Simmental bulls. The artificial rumen culture fluid were continuously cultured in vitro for 48 h. Based on the diets they were fed, 24 healthy Chinese Simmental bulls (average weight of 495.93 ±10.89 kg) were randomly divided into two groups, with 12 bulls in each group, which were fed TMR or FTMR. The study lasted 56 d. In in vitro experiments, the neutral detergent fiber degradability and total volatile fatty acid, propionate, iso-butyrate, iso-valerate and valerate concentrations were greater in the FTMR group (p<0.05) than in the TMR group. However, the methane production, pH and A/P of the FTMR group tended to be lower (p<0.05) than those of the TMR group. In the in vivo experiments, the average daily gain, eating rate, and feed efficiency of the FTMR groups were greater (p<0.05) than those of the TMR group. Similarly, the NDF degradability of the FTMR group was greater (p<0.05) than that of the TMR group. Compared to those in the TMR group, the concentrations of total volatile fatty acids, iso-butyrate, propionate and butyrate were greater in the FTMR group (p<0.05), and the A/P ratio was lower (p<0.05). Similarly, cellulase, xylanase, and β-glucosidase activities were greater (p<0.05) in the FTMR group than in the TMR group. Corn straw-based fermented total mixed rations supplemented with exogenous cellulase play a vital role in decreasing the structural carbohydrate content of TMR and ruminal methane production in vitro, improving nutrient digestion and absorption, optimizing rumen fermentation, and improving the growth performance of beef cattle.

Volatile Fatty Acids from Household Food Waste: Production and Kinetics

Household food waste (HFW), which is rich in organic matter, is a good candidate for producing added-value bio-based chemicals, such as volatile fatty acids (VFAs), by acidogenic fermentation processes. However, the lack of design tools, such as appropriate kinetic models, hinders the implementation of this technology because the results of these processes are affected by operational factors. In this work, VFA production by the acidogenic fermentation of HFW under uncontrolled pH levels (4–5) was studied at thermophilic (55 °C) and mesophilic (35 °C) temperature conditions. Batch reactors were used to digest HFW, and VFA production and the individual acid distributions were measured at different fermentation times from 0 to 624 h. The results showed higher individual and total VFA production at 35 °C and 120 h of fermentation time as a consequence of the competition between the VFA production and decomposition reactions. Acetic and valeric acids were VFAs mainly produced as a result of a high content of proteins in the initial substrate, and a small amount of propionic and butyric acids were present. A simplified kinetic model was successfully developed to represent the complex process of VFA formation from the acidogenic fermentation of HFW. A simple mechanism for the production–decomposition of VFAs, corresponding to a zero-order reaction for the first 48 h and a single consecutive reaction from that time on, was proposed. For both mesophilic and thermophilic conditions, the suggested kinetic model was able to predict the individual and total concentrations of VFAs along the fermentation time.

Feeding almond hulls to light lambs: Effects on growth performance, digestive utilization and blood metabolites

The effects of including almond hulls (AH) in the concentrate fed to light lambs on animal performance, diet utilization, and blood metabolites. Three isonitrogenous and isoenergetic concentrates were formulated with either 0 (control), 6 (AH6) or 12 (AH12) g of AH per 100 g (fresh matter basis). Thirty Manchega breed lambs (15 males and 15 females; 12.3 ± 0.18 kg body weight (BW)) were distributed into six homogeneous groups according to BW (3 groups of each sex), which were randomly assigned within sex to each experimental concentrate. Lambs were fed concentrate and barley straw ad libitum until reaching about 23.0 kg BW. There were no differences (P ≥ 0.182) between groups in final BW, intake of concentrate and straw, and feed conversion rate. Average daily gain and digestibility of dry matter and crude protein tended (P < 0.10) to decrease by the AH inclusion in the concentrate. Lambs fed AH12 showed greater (P < 0.05) urinary losses than those fed the control concentrate (15.4 and 11.5 g per 100 g of N intake, respectively), despite the similar N intake in all groups. Feeding AH did not affect (P ≥ 0.213) blood concentrations of albumin, globulins, urea, creatinine, glucose, total bilirubin and cholesterol or blood activities of hepatic enzymes. The post-mortem analysis revealed no differences among groups in pH and total volatile fatty acids (VFA) concentrations in the rumen of lambs, but NH3-N concentrations were lower (P < 0.05) in the lambs fed the concentrates with AH. In addition, lambs fed AH12 diet had lower (P < 0.05) molar proportions of propionate and greater (P < 0.05) proportions of butyrate compared with lambs fed control and AH6 concentrate. In general, no concentrate x sex interactions were observed, and sex had no effect on the measured parameters except for some differences in ruminal VFA profile. In conclusion, AH can be included at in light lambs’ concentrate up to 12 g per 100 g of concentrate without impairing animal growth.

A dual-chamber Microbial Electrolysis Cell for electromethanosynthesis from the effluent of cheese whey dark fermentation

Dark fermentation of cheese whey (CW) for the production of biohydrogen generates an acidic effluent, containing high concentrations of volatile fatty acids, which needs to be further treated before disposal and possibly further valorised. This study develops a dual-chamber Microbial Electrolysis Cell (MEC) that achieves simultaneously the reduction of the organic content of this effluent to environmentally acceptable levels, along with bio-electrochemical reduction of CO2 to CH4. The MEC was operated for 140 days and the effect of the following conditions on the MEC performance was examined: (a) the feed concentration of the acidic fermentate (in the range 6–81 gCOD/L), (b) the conductivity of the feed modified via KCl addition (range 2–22 mS/cm), (c) the MEC operation mode (with or without catholyte renewal) and (d) the solids content (modified via CW filtration prior to its use). The results showed that high COD removal (>95 %) was achieved in all cases, along with a CH4 production of up to 1.1 mmol/gCODconsumed. The best performance of the cell was obtained for a feed COD concentration of ∼30 gCOD/L and a feed conductivity of ∼15 mS/cm; these conditions resulted in a COD removal exceeding 99 %, a CH4 production of 1.1 mmolCH4/gCODconsumed and a net energy production of 15.8 % compared to the energy demand of the system. The electrochemical study of the system revealed that higher and lower feed COD concentrations were characterized by higher internal resistances. The results indicate that the MEC can be exploited for further treatment and valorization of a high-strength effluent along with the production of CH4 with an energy surplus, as an efficient waste-to-energy technology.

High value-added chemical production through anaerobic codigestion of corn straw with a microbial consortium, cow manure and cow digestion solution

ObjectivesThis study investigated the codigestion of corn straw (CS) with cow manure (CM), cow digestion solution (CD), and a strain consortium (SC) for enhanced volatile fatty acid (VFA) production. The aims of this study were to develop a sustainable technique to increase VFA yields, examine how combining microbial reagents with CS affects VFA production by functional microorganisms, and assess the feasibility of improving microbial diversity through codigestion. MethodsBatch experiments evaluated VFA production dynamics and microbial community changes with different combinations of CS substrates with CM, CD, and SC. Analytical methods included measuring VFAs by GC, ammonia and chemical oxygen demand (COD) by standard methods and microbial community analysis by 16S rRNA gene sequencing. ResultsCodigesting CS with the strain consortium yielded initial VFA concentrations ranging from 0.6 to 1.0 g/L, which were greater than those of the other combinations (0.05–0.3 g/L). Including CM, and CD further increased VFA production to 1.0–2.0 g/L, with the highest value of 2.0 g/L occurring when all four substrates were codigested. Significant ammonium reduction (194–241 mg/L to 29–37 mg/L) and COD reduction (3310–5250 mg/L to 730–1210 mg/L) were observed. Codigestion with CM and CD had greater Shannon diversity indices (3.19–3.24) than did codigestion with the other consortia (2.26). Bacillota dominated (96.5–99.6 %), with Clostridiales playing key roles in organic matter breakdown. ConclusionsThis study demonstrated the feasibility of improving VFA yields and harnessing microbial diversity through anaerobic codigestion of lignocellulosic and animal waste streams. Codigestion substantially enhanced VFA production, which was dominated by butyrate, reduced ammonium and COD, and enriched fiber-degrading and fermentative bacteria. These findings can help optimize codigestion for sustainable waste management and high-value chemical production.

Modulations in gastrointestinal microbiota during postpartum period fulfill energy requirements and maintain health of lactating Tibetan cattle.

Postpartum period of dairy cattle is an important phase of their life mainly associated with the changes in physiology, rumen function, and energy metabolism. Studies have shown that gut microbial composition undergoes drastic changes during the postpartum period. However, little is known about the temporal variations in digestive tract microbiota in postpartum Tibetan cattle. The aim of this study was to investigate the temporal variations in blood metabolites, ruminal fermentation, and microbial community of oral, rumen, and gut in lactating Tibetan cattle during postpartum. We collected blood, saliva, rumen fluid, and fecal samples from lactating Tibetan cattle during 1st week (1 W), the 2nd week (2 W), the 1st month (1 M), and the 2nd month (2 M) of the postpartum period. The microbiota of saliva, rumen fluid, and fecal samples were assessed using 16S rRNA sequencing. The rumen volatile fatty acid and blood parameters were also quantified. The content of volatile fatty acids (VFAs) and blood parameters showed opposite tendency to each other and reached to stability at 2 M. Rumen microbiota showed the highest alpha diversity compared to other two sites. At phylum level, the oral cavity was dominated by Proteobacteria, while most dominant phylum in rumen and feces were Firmicutes and Bacteroidetes, respectively. The dominant genera in oral cavity were Moraxella and Bibersteinia, while genera Prevotella 1 and Ruminococcaceae UCG-005 were dominant in rumen and fecal samples, respectively. Microbial network analysis revealed that most of the active genera in all networks belonged to phylum Firmicutes, indicating the importance of this phyla during postpartum period of lactating cattle. The functional analysis revealed distinct division of labor among three gastrointestinal sites associated with defense, fatty acid synthesis, and maintaining health of host. All in all, our findings provide insights into the metabolic and microbial changes of lactating Tibetan cattle and help to the improvement of the management strategies.

Dynamic Changes in the Nutrient Digestibility, Rumen Fermentation, Serum Parameters of Perinatal Ewes and Their Relationship with Rumen Microbiota.

Changes in physiological and biochemical parameters are crucial for the reproductive performance and health of perinatal ewes. This study investigated the temporal variations in feed intake, nutrient digestibility, serum parameters, and ruminal fermentation on days 21, 14, and 7 before lambing (Q21, Q14, and Q7) and days 3, 7, and 14 after lambing (H3, H7, and H14). The results showed that dry matter intake (DMI) and glucose (Glu) gradually decreased (p < 0.05) before lambing and increased (p < 0.05) after lambing. The digestibility of dry matter (DMD), crude protein (CPD), and acid detergent fiber (ADFD) increased (p < 0.05) before lambing, then decreased (p < 0.05) on day H3, and then increased (p < 0.05) on day H14. The rumen pH, NH3-N, and triglycerides (TG) gradually increased (p < 0.05) before lambing and were higher (p < 0.05) on day Q7 than after lambing. The concentrations of acetate, butyrate, and total volatile fatty acids (T-VFA) were lower (p < 0.05) on day Q7 than those on days Q21 and Q14, then increased (p < 0.05) after lambing. Total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C) concentrations gradually decreased (p < 0.05) in perinatal ewes. BHBA and NEFA concentrations were lower (p < 0.05) on day Q21 than those from days Q14 to H14. The rumen microbiota compositions were different (p < 0.05) in perinatal ewes, and g_Anaerovibrio, g_Lachnobacterium, and g_Schwartzia were positively correlated (p < 0.05) with DMI, Glu, acetate, propionate, and T-VFA, and negatively correlated (p < 0.05) with LDL-C. g_Bacillus was negatively correlated (p < 0.05) with DMI, Glu, acetate, propionate, butyrate, and T-VFA, but positively correlated (p < 0.05) with rumen pH and LDL-C. In summary, the DMI, nutrient digestibility, rumen fermentation, and serum parameters changed during the perinatal period of ewes, and the changes in DMI, serum glucose, acetate, propionate, and T-VFA were related to the rumen bacteria.

Mealworm larvae and black soldier fly larvae as novel protein supplements for cattle consuming low-quality forage.

The global population is projected to increase, indicating that there will be greater demand for animal protein to meet the associated food needs. This demand will place additional pressure on livestock systems to increase output while also minimizing natural resource inputs. Insect protein has emerged as a potential alternative to conventional protein feeds, such as soybean meal. Mealworm larvae (MWL; Tenebrio molitor) have been studied in poultry and swine as an alternative protein source; however, there is no research currently evaluating MWL for cattle. Black soldier fly larvae (BSFL; Hermetia illucens) have also received attention for their potential use in livestock feed due to their scalability and nutritional value, but research in cattle is limited. The objective of this study was to evaluate the effects of whole-dried MWL and defatted BSFL as protein supplements for cattle consuming forage. Five ruminally cannulated steers were utilized in a 5 × 5 Latin square experiment to determine how MWL and BSFL supplementations affect forage utilization. Steers consuming ad libitum low-quality forage (76.5% neutral detergent fiber [NDF], 4.2% crude protein) were provided one of the five treatments each period: 1) control with no supplement (CON), 2) soybean meal (CONV), 3) BSFL, 4) MWL, or 5) 50/50 by-weight blend of BSFL and MWL (MIX). All treatments were provided at 100 mg N/kg BW and periods included 8 d for treatment adaptation, 5 d for intake and digestion, and 1 d for ruminal fermentation measures. Protein supplementation stimulated forage organic matter intake (FOMI; P ≤ 0.01) relative to CON (3.28 kg/d). There was a significant difference in FOMI (P ≤ 0.01) between BSFL (4.30 kg/d) and CONV (4.71 kg/d), but not between CONV and MWL (P = 0.06, 4.43 kg/d). Total digestible OM intake (TDOMI) was also stimulated by the provision of protein (P ≤ 0.01), from 1.94 kg/d for CON to an average of 3.24 kg/d across protein supplements. Organic matter digestibility (OMD) and NDF digestibility (NDFD) were not affected by treatment (P ≥ 0.37), for an average OMD of 66.5% and NDFD of 62.7%. There was also no treatment effect on ruminal volatile fatty acid (P = 0.96) or ammonia-N (P = 0.22) concentrations. These data indicate that MWL may stimulate forage utilization by beef cattle to a greater extent than BSFL, but both are viable protein supplements.