Individual Volatile Fatty Acids Research Articles

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.

Acid-base properties of non-protein nitrogen affect nutrients intake, rumen fermentation and antioxidant capacity of fattening Hu sheep.

This study conducted a comparison of the effects of non-protein nitrogen with different acid-base properties on feed intake, rumen fermentation, nutrient digestion and antioxidant capacity in fattening Hu sheep. Sixteen fattening male sheep (31.43 ± 2.41 kg) with permanent rumen cannulas were randomly assigned to two dietary treatments: 1% urea and 1.78% ammonium chloride (NH4Cl, AC). A 42 days experimental period was conducted, with 14 days for adaptation and 28 days for treatment. Daily feed intake was recorded and various samples including feed, feces, rumen fluid, and blood were collected at different time points during the final week. The results indicated that the urea group had significantly higher dry matter intake, average daily gain, and gain efficiency in comparison to the AC group (p < 0.01). There was no difference in rumen pH and concentration of ammonia nitrogen between different groups (p > 0.05), but the rumen pH of urea group was higher than that of the AC group at 1 and 3 h after feeding (p < 0.05). The urea group exhibited higher concentrations of total volatile fatty acids (VFA) and individual VFAs compared to the AC group at all-time points (p < 0.01). Compared to the urea group, the intake of all nutrients decreased in the AC group (p < 0.01), but the digestibility of dry matter and organic matter increased significantly (p < 0.01), and the digestibility of CP had an increasing trend (p = 0.06) in the AC group. Additionally, the urea group had lower levels of serum glucagon-like peptide-1, peptide YY, Cl, total protein and globulin than the AC group (p < 0.05). The overall levels of HCO3-, superoxide dismutase, glutathione peroxidase, catalase, albumin/globulin, blood urea nitrogen and total cholesterol in the urea group increased significantly compared to the AC group (p < 0.05). It was concluded that adding urea to the high-concentrate diet resulted in increased rumen pH and improved rumen fermentation and growth performance in fattening sheep compared to NH4Cl addition. Furthermore, urea addition improved sheep's antioxidant capacity and maintained their acid-base balance more effectively as compared to NH4Cl.

The effects of including sprouted barley with alfalfa hay in the diet on ruminal health and performance of cow-calf pairs.

The world population is growing exponentially, increasing demand to produce high-quality protein for human consumption. Changes in weather patterns, drought, and decreased land resources due to urbanization have increased thestrain on the agriculture sector to meet world demands. An alternative method to combat these issues and continue to produce high-quality livestock feed would be through a controlled environment vertical farming system. Commonly, cereal grains, such as barley, are used in these systems to produce livestock feed. However, there is little information on the viability of feeding sprouted grains to beef cattle. Two diets of either feeder-quality alfalfa hay (n = 10 pairs; ALF) or the same alfalfa hay and sprouted barley (SB; 12.6% dry matter [DM]; n = 10 pairs) were fed for 90 d to Angus pairs with a steer calf during mid to late lactation. On days 0 and 90, body weight (BW), milk, rumen fluid, and body condition score were collected from cows and hip height and BW were recorded for calves. On day 10, BW was recorded for cows and calves and rumen fluid was collected from cows. Rumen fluid was also collected from cows on day 45. On day 55, BW was collected for both cows and calves and milk from cows. Intake was recorded throughout the trial via bunks with Vytelle technology. The PROC MIXED procedure of SAS was used to analyze all data with the day as a repeated measure to determine the main effect of diet. Individual volatile fatty acids (VFA) were measured as a percent of total VFA. No differences (P ≥ 0.16) were observed in calf BW, hip height, milk protein, fat, lactose, calf DM intake (DMI), or cow DMI. Cows fed SB tended (P = 0.08) to have a decreased somatic cell count compared to ALF. Percent butyrate was impacted by diet × day (P = 0.02), but no difference (P > 0.09) at any time points were detected. Additionally, a diet × day effect (P = 0.001) on rumen pH demonstrated that both groups stayed consistent until day 45 and then SB pH decreased the last 45 d. There was a day effect for total VFA (P = 0.0009), acetate:propionate (Ac:Pr; P < 0.0001), acetate (P < 0.0001), and propionate (P < 0.0001) demonstrating that total VFA, acetate, and Ac:Pr all increased throughout the trial, while propionate decreased. These results indicate that SB can be a potential alternative feed at this stage of production as it does not negatively impact health or production, but does affect the rumen pH and proportion of some VFA.

Ruminal inocula with distinct fermentation profiles differentially affect the in vitro fermentation pattern of a commercial algal blend.

The in vitro rumen batch technique is widely used for screening novel feed sources; however, it remains unclear to what extent the in vitro fermentability of non-conventional feed sources is affected by non-adapted ruminal inocula. Thus, in this study, we evaluated the effects of distinct ruminal inocula on the in vitro fermentation parameters of a sustainable non-conventional feed, a commercially available algal blend composed of microalgae (Chlorella vulgaris and Nannochloropsis oceanica) and seaweeds (Ulva sp. and Gracilaria gracilis). First, four late-lactation Holstein cows were fed four forage-based diets varying only in the proportions of basal forage (100% corn silage, 70% corn silage and 30% haylage, 30% corn silage and 70% haylage, and 100% haylage) in a 4 × 4 Latin square design with the last square omitted. After 3 weeks of adaptation, haylage-based diets resulted in ruminal fermentation parameters distinct from those promoted by corn silage-based diets, as reflected in increased pH, ammonia-N contents, and acetate proportions. Individual ruminal fluids derived from each of the four diets were further used as inocula in in vitro incubations. Here, a 1:1 mixture of corn silage and haylage was supplemented with 0, 5, 10, or 15% algal blend and incubated with each inoculum for 24 h in a 4 × 4 factorial design. Total gas and methane production decreased with inocula from cows fed haylage-based diets and with increasing algal blend supplementation levels. The fermentation pH increased and the ammonia-N contents decreased with inocula from cows fed haylage-based diets; however, these parameters were not affected by algal blend inclusion levels. The interaction between the ruminal inoculum source and the algal blend supplementation level affected the total volatile fatty acids (VFA) and the proportions of most individual VFA. Total VFA production decreased with increasing algal supplementation levels, particularly with inocula from cows fed 30% corn silage and 70% haylage; the acetate, propionate, and valerate proportions were only affected by algal blend levels under incubation with 100% corn silage inocula. Overall, our findings highlight the importance of the ruminal inoculum source when assessing the fermentability of non-conventional feed as well as the potential of the algal blend as a natural modulator of ruminal fermentation.

91 Mealworm and black soldier fly larvae as protein supplements for beef steers consuming forage

Abstract The global population is projected to increase, indicating 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 environmentally sustainable alternative to conventional protein feeds, such as soybean meal. Further, insect protein does not compete in the human food market as the products of conventional oil crops often do. Mealworm larvae (MWL) has been studied in poultry and swine as an alternative protein feed; however, there is not currently research evaluating MWL for cattle. Black soldier fly larvae (BSFL) has also received attention for its potential use in livestock feed due to its 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. These procedures were approved by IACUC at Texas State University (#7726). Five ruminally cannulated steers were utilized in a 5×5 Latin square experiment to determine how MWL and BSFL supplementation affect forage utilization. Steers consuming low-quality forage (4.2% crude protein) were provided one of five treatments each period: 1) control with no supplement (CON), 2) soybean meal (CONV), 3) BSFL, 4) MWL, and a 5) 50% BSFL and 50% MWL by-weight (MIX). Supplements were provided at 100 mg N/kg BW. Periods included 8-d for treatment adaptation, 5-d for intake and digestion measurements, and 1-d for ruminal fermentation measures. Dry matter (DM), organic matter (OM), CP, neutral detergent fiber (NDF), and acid detergent fiber (ADF) were determined for diet, ort, and feces. Protein supplementation stimulated forage OM intake (P ≤ 0.01) relative to CON. There was a significant difference in FOMI (P ≤ 0.01) between BSFL and CONV. Steers receiving CONV treatment consumed 4.71 kg FOMI/d, which was significantly greater (P ≤ 0.01) than those receiving BSFL (4.30 kg/d). There were not differences in FOMI between other treatment groups. Total digestible OM intake (TDOMI) was stimulated by protein supplementation (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 neutral detergent fiber 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 not a treatment effect (P = 0.96) on total volatile fatty acid (VFA) concentrations, although there were some shifts in molar proportions of individual VFAs across treatments. These data indicate that MWL may be more efficacious than BSFL in stimulating forage utilization in beef cattle, but both are viable protein supplements.

Effect of dietary supplementation with zinc-methionine on ruminal enzyme activities, fermentation characteristics, methane production, and nutrient digestibility: An in vitro study.

The principal objective of this research was to examine the influence of zinc-methionine (Zn-Met) addition on feed on the in vitro ruminal enzyme activities, fermentation characteristics, methane production, and digestibilities of feed nutrients. The dosage of Zn-Met as a source of organic Zn was added to feed based on dry matter (DM) as follows: 0-without Zn addition (CON), 30 Zn mg/kg-low (LZM), 60 Zn mg/kg-medium (MZM), and 90 Zn mg/kg-high (HZM). The results indicated significant impacts of Zn-Met addition on various parameters. Compared to the CON group, all Zn-Met treatments resulted in increased total volatile fatty acids (VFA) (linear; p < 0.001), carboxymethyl-cellulase activity (linear; p < 0.001), and gas production at 48-h of incubation (linear; p < 0.001, quadratic; p < 0.001). Additionally, the MZM and HZM groups exhibited higher levels of amylase activity (linear; p < 0.001), protease activity (linear; p = 0.006), microbial protein (linear; p = 0.009), DM digestibility (linear; p < 0.001), organic matter (OM) digestibility (linear; p < 0.001), crude protein (CP) digestibility (linear; p = 0.004), and crude fiber (CF) digestibility (linear; p = 0.003) than CON treatment. However, the treatments did not have any noteworthy effects on pH, the individual VFA (acetate, propionate, and butyrate) proportions, NH3-N concentration, and methane production (p > 0.05). It could be summarized that supplementing 60 and 90 Zn mg/kg DM as Zn-Met could improve the in vitro ruminal enzyme activities, fermentation characteristics, and nutrient digestibility without affecting methane production.

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.

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.

361 The Effects of Feeding Sprouted Barley on Cow Calf Pairs Health and Performance

Abstract Currently the world population is growing exponentially, which increases the demand to produce high-quality protein. Changes in weather patterns, such as drought, and decreased land resources due to urbanization, increase the strain on the agriculture sector to meet world demands. An alternative method to remedy these issues and still produce high quality livestock feed is through controlled environment vertical farming systems. Sprouted grains are one feed these systems can produce. However, there is little information on the effects of feeding sprouted grains to cattle. Angus cows with a steer calf were fed either feeder quality alfalfa (n =10 pairs) or the same alfalfa and sprouted barley (12.5% DM; n = 10 pairs) for 90 days. On days 0 and 90, body weight, milk, rumen fluid and BCS were collected from cows and hip height and weight were recorded for calves. On day 10, weight was recorded for cows and calves and rumen fluid and milk were obtained from cows. On day 45, rumen fluid and milk were collected from cows. On day 55, body weights were collected for both cows and calves and milk from cows. Intake was recorded throughout the trial via bunks with Vytelle technology. PROC MIXED procedure of SAS was used to analyze all data with day as a repeated measure to determine the main effect of treatment. Individual volatile fatty acids (VFA) were measured as a percent of total VFA present. No differences (P ≥ 0.16) were observed in calf weight, hip height, milk protein, fat, lactose, calf DM intake, or cow DM intake. Cows fed barley sprouts tended (P = 0.08) to have a decreased somatic cell count compared with alfalfa fed cows. There was a treatmentxday effect (P = 0.004) for isobutyrate, such that the treatment and control decreased over time, but the control remained consistent the last 45 days. A treatmentxday effect (P = 0.02) was also observed for butyrate indicating that both remained consistent over the first 45 days and then treatment increased over the last 45 days. Additionally, treatmentxday effect (P = 0.001) for rumen pH demonstrated that both groups stayed consistent until day 45 and then treatment pH decreased the last 45 days. There was a day affect for total VFA (P = 0.0009), acetate:propionate (P &amp;lt; 0.0001), acetate (P &amp;lt; 0.0001), and propionate (P &amp;lt; 0.0001) demonstrating that total VFA and acetate increased throughout the duration of the trial and acetate:propionate and propionate decreased throughout the trial, while the acetate:propionate ratio increased (P &amp;lt; 0.0001) the duration of the trial. Cows receiving sprouted barley produced more (P = 0.02) capronate than control. These results indicate that sprouted barley can be an alternative feed at this stage in production without having a negative impact on health or production but does change the rumen pH and proportion of some VFA.

Short communication: Quantifying postruminal starch fermentation in early-lactation Holstein-Friesian cows.

It has previously been shown that fermentation may contribute substantially to small intestinal carbohydrate disappearance. The fact that the energetic efficiency of starch fermentation is considerably less than that of enzymatic digestion of starch, makes it of nutritional importance to quantify the level of postruminal starch fermentation for dairy cows. Hence, we subjected six rumen-fistulated Holstein-Friesian dairy cows (48±17days in milk) to 5 d of continuous abomasal infusions of 0.0, 2.5, and 5.0mol NH4Cl/d, with and without 3kg ground maize/d, followed by 2d of rest in a 6×6 Latin square design. A total mixed ration (TMR) consisting of (DM basis) 70% grass silage and 30% concentrate was fed at 95% of ad libitum intake. Separation of postruminal starch disappearance into enzymatically digested starch and fermented starch was based on the measurement of natural 13C enrichment of the TMR, abomasally infused ground maize, and resulting 13C enrichment of faeces. Within each cow, 0.0, 2.5, and 5.0mol NH4Cl/d without ground maize served as control for the same levels of NH4Cl with 3kg ground maize/d. Abomasal infusion of ground maize was associated with increased total DM and starch intake, faecal starch excretion, and digestibility of starch, and with decreased digestibility of DM and N. The increased faecal volatile fatty acid (VFA) output and 13C enrichment of the individual VFA indicate increased starch fermentation with abomasally infused ground maize. On average, 1311g starch/d was postruminally fermented, representing 60.8% of total starch intake. Overall, postruminal starch fermentation of early-lactation dairy cows abomasally infused with 3kg ground maize/d is considerable and may result in substantial amounts of VFA rather than glucose production.

Effects of Exogenous Oral Infusion of Volatile Fatty Acids on Ileal Microbiome Profiling and Epithelial Health in Goats

The role of volatile fatty acids (VFAs) in ruminal fermentation is well studied, but their effects on the ileal microbiome and epithelial health remain less explored. In this study, we investigated the impact of the exogenous oral infusion of three VFAs, sodium acetate (NaAc), propionate (NaPr), and butyrate (NaBu), on the VFA concentrations in ileal contents, as well as ileal microbiome profiling and epithelial health parameters (inflammatory cytokine and tight junctions) in goats. The data demonstrated that the oral infusion of three VFAs can enhance VFA production by increasing the proportions of each individual VFA and the total VFAs. Then, the microbiome revealed distinct microbial succession patterns and altered microbial diversities in response to the oral infusion of VFA treatments. Moreover, the oral infusion of each VFA had unique effects on the ileal bacterial community, with potential implications for epithelial health. Notably, the oral infusion of VFAs demonstrated potential anti-inflammatory effects, as evidenced by reduced IL-6 levels in the NaPr group and increased IL-10 levels in the NaAc group. Notably, the oral infusion of VFAs did not directly impact the tight junction concentrations, such as Claudin1, Occludin, and ZO-1. Lastly, the correlation analyses identified specific relationships between the ileal bacteria and epithelial health parameters, and Prevotella was positively correlated with IL-6 and IL-1β, while Bifidobacterium was positively correlated with IL-10. These results highlighted the crosstalk between VFAs, the ileal microbiome, and the health of the small intestine. Our findings had significant implications for optimizing ruminant nutrition, enhancing epithelial health, and promoting sustainable livestock production practices.

Effects of Administration of Prebiotics Alone or in Combination with Probiotics on In Vitro Fermentation Kinetics, Malodor Compound Emission and Microbial Community Structure in Swine

The objective of this study was to evaluate the effect of Lactobacillus amylovorus, L. plantarum, galacto-oligosaccharide (GOS) and their synbiotic formulations on pH, volatile fatty acids (VFA), malodor, and microbial ecological profiles through a 24-h in vitro fermentation model. Inclusion of GOS alone and in synbiotic combination with either probiotic resulted in consistently lower pH and higher total gas volumes at 12 and 24 h of incubation. Notably, concentrations of odorous compounds (hydrogen sulfide, H2S and methyl mercaptan, CH3SH) in the total gas produced were significantly lower in these GOS-containing treatments relative to the controls and probiotic-only-treated groups. However, although ammonia showed an initial relative reduction at 12 h, concentrations did not differ among treatments at 24 h. Further, the GOS-containing treatments had remarkably higher total and individual VFAs, including acetate, propionate, and butyrate, relative to controls and the probiotic-only treatments. Analysis of microbial composition and diversity showed clustering of GOS-containing treatments away from the controls and probiotic-only treatments at 12 and 24 h of incubation. Our study suggests that GOS supplementation (alone or in combination with L. amylovorus or L. plantarum probiotic strains) has the potential to increase VFA production in the swine gut while lowering emissions of malodorous compounds, except ammonia, in their manure.

Capric and lauric acid mixture decreased rumen methane production, while combination with nitrate had no further benefit in methane reduction

Abstract This study aimed to evaluate the methane-reducing potential of individual and combined treatments of low levels of nitrate (NIT) and a mixture of capric/lauric acid (CL) in dairy cows. Both in vitro and in vivo experiments were conducted. In the in vitro experiment, the anti-methanogenic effects of NIT (1.825 mmol/l) and CL (250 mg/l; capric acid, 125 mg/l + lauric acid, 125 mg/l) were evaluated in a 2 × 2 factorial design using consecutive batch incubations with rumen fluid. The NIT and CL reduced (P&lt;0.05) methane production by 9.2% and by 21.3%, respectively. However, combining NIT with CL did not show (P&gt;0.05) any benefit in methane reduction compared to the use of CL alone. In the in vivo experiment, eight multiparous dry Holstein cows were fed two diets in a crossover design for two 21-day periods (14 days of adaptation and 7 days of sampling). The treatments were: 1) silage-based basal diet + 100 g stearic acid per cow/d (CON) and 2) silage-based basal diet + 50 g capric acid + 50 g lauric acid per cow/d (CL). Gas emissions were measured using open-circuit respiration chambers. Methane production (g/d) was reduced (by 11.5%; P = 0.012) when the diet was supplemented with CL. However, supplementation with CL increased ruminal ammonia-N concentration (by 28.5%; P = 0.015) and gas ammonia production (g/d; by 37.2%; P = 0.005). Ruminal pH, protozoa count, and total and individual volatile fatty acid concentrations (VFA ) did not differ (P&gt;0.05) between the treatments. Treatment did not affect the intake and apparent total tract digestibility (P&gt;0.05). In conclusion, our results suggest that low CL levels have anti-methanogenic potential. However, low levels of CL may compromise nitrogen use efficiency.

Evaluation of Rumen Fermentation and Microbial Adaptation to Three Red Seaweeds Using the Rumen Simulation Technique.

Several red seaweeds have been shown to inhibit enteric CH4 production; however, the adaptation of fermentation parameters to their presence is not well understood. The objective of this study was to examine the effect of three red seaweeds (Asparargopsis taxiformis, Mazzaella japonica, and Palmaria mollis) on in vitro fermentation, CH4 production, and adaptation using the rumen simulation technique (RUSITEC). The experiment was conducted as a completely randomized design with four treatments, duplicated in two identical RUSITEC apparatus equipped with eight fermenter vessels each. The four treatments included the control and the three red seaweeds added to the control diet at 2% diet DM. The experimental period was divided into four phases including a baseline phase (d 0-7; no seaweed included), an adaptation phase (d 8-11; seaweed included in treatment vessels), an intermediate phase (d 12-16), and a stable phase (d 17-21). The degradability of organic matter (p = 0.04) and neutral detergent fibre (p = 0.05) was decreased by A. taxiformis during the adaptation phase, but returned to control levels in the stable phase. A. taxiformis supplementation resulted in a decrease (p < 0.001) in the molar proportions of acetate, propionate, and total volatile fatty acid (VFA) production, with an increase in the molar proportions of butyrate, caproate, and valerate; the other seaweeds had no effect (p > 0.05) on the molar proportions or production of individual VFA. A. taxiformis was the only seaweed to suppress CH4 production (p < 0.001), with the suppressive effect increasing (p < 0.001) across phases. Similarly, A. taxiformis increased (p < 0.001) the production of hydrogen (H2, %, mL/d) across the adaptation, intermediate, and stable phases, with the intermediate and stable phases having greater H2 production than the adaptation phase. In conclusion, M. japonica and P. mollis did not impact rumen fermentation or inhibit CH4 production within the RUSITEC. In contrast, we conclude that A. taxiformis is an effective CH4 inhibitor and its introduction to the ruminal environment requires a period of adaptation; however, the large magnitude of CH4 suppression by A. taxiformis inhibits VFA synthesis, which may restrict the production performance in vivo.

Effects of Cashew Nut Shell Extract on Ruminal Fermentation and Nutrient Digestibility under Continuous Culture

The overall objective of this study was to determine the dose response to four levels of cashew nut shell extract in a granulated form (CNSE, containing 59% anacardic acid and 18% cardol) on culture pH, rumen fermentation metabolites, and apparent nutrient digestibility in continuous culture fermenters. The study was conducted as a generalized randomized complete block design with four treatments and four replications per treatment. The four treatments were randomly assigned to eight fermenters for two incubation runs of 10 d. Treatments consisted of (1) Control (CO, no CNSE), (2) Control plus 100 ppm of CNSE, (3) Control plus 200 ppm of CNSE, and (4) Control plus 300 ppm of CNSE. Fermenters were fed 52 g/d (DM basis) of a total mixed ration (TMR; 17.0% crude protein (CP), 29.7% NDF, and 29.9% starch), divided between two feedings at 0800 and 2000 h. The apparent digestibility of dry matter (DM), organic matter (OM), and neutral detergent fiber (NDF) were not affected by CNSE supplementation. Similarly, CNSE had no effect on culture pH, total volatile fatty acids (VFA) or individual VFA molar proportions. These results suggest that at the dosages evaluated in this study, CNSE has no impact on the rumen fermentation profile and the apparent nutrient digestibility under continuous culture conditions.

Characterizing ruminal acidosis risk: A multiherd, multicountry study

A multicenter observational study was conducted on early lactation Holstein cows (n = 261) from 32 herds from 3 regions (Australia, AU; California, CA; and Canada, CAN) to characterize their risk of acidosis into 3 groups (high, medium, or low) using a discriminant analysis model previously developed. Diets ranged from pasture supplemented with concentrates to total mixed ration (nonfiber carbohydrates = 17 to 47 and neutral detergent fiber = 27 to 58% of dry matter). Rumen fluid samples were collected <3 h after feeding and analyzed for pH, and ammonia, d- and l-lactate, and volatile fatty acid (VFA) concentrations. Eigenvectors were produced using cluster and discriminant analysis from a combination of rumen pH, and ammonia, d-lactate, and individual VFA concentrations and were used to calculate the probability of the risk of ruminal acidosis based on proximity to the centroid of 3 clusters. Bacterial 16S ribosomal DNA sequence data were analyzed to characterize bacteria. Individual cow milk volume, fat, protein, and somatic cell count values were obtained from the closest herd test to the rumen sampling date (median = 1 d before rumen sampling). Mixed model analyses were performed on the markers of rumen fermentation, production characteristics, and the probability of acidosis. A total of 26.1% of the cows were classified as high risk for acidosis, 26.8% as medium risk, and 47.1% as low risk. Acidosis risk differed among regions with AU (37.2%) and CA (39.2%) having similar prevalence of high-risk cows and CAN only 5.2%. The high-risk group had rumen phyla, fermentation, and production characteristics consistent with a model of acidosis that reflected a rapid rate of carbohydrate fermentation. Namely, acetate to propionate ratio (1.98 ± 0.11), concentrations of valerate (2.93 ± 0.14 mM), milk fat to protein ratio (1.11 ± 0.047), and a positive association with abundance of phylum Firmicutes. The medium-risk group contains cows that may be inappetant or that had not eaten recently or were in recovery from acidosis. The low-risk group may represent cattle that are well fed with a stable rumen and a slower rumen fermentation of carbohydrates. The high risk for acidosis group had lower diversity of bacteria than the other groups, whereas CAN had a greater diversity than AU and CA. Rumen fermentation profile, abundance of ruminal bacterial phyla, and production characteristics of early lactation dairy cattle from 3 regions were successfully categorized in 3 different acidosis risk states, with characteristics differing between acidosis risk groups. The prevalence of acidosis risk also differed between regions.

Network analysis to evaluate complexities in relationships among fermentation variables measured within continuous culture experiments.

The objective of this study was to leverage a frequentist (ELN) and Bayesian learning (BLN) network analyses to summarize quantitative associations among variables measured in 4 previously published dual-flow continuous culture fermentation experiments. Experiments were originally designed to evaluate effects of nitrate, defaunation, yeast, and/or physiological shifts associated with pH or solids passage rates on rumen conditions. Measurements from these experiments that were used as nodes within the networks included concentrations of individual volatile fatty acids, mM and nitrate, NO3-,%; outflows of non-ammonia nitrogen (NAN, g/d), bacterial N (BN, g/d), residual N (RN, g/d), and ammonia N (NH3-N, mg/dL); degradability of neutral detergent fiber (NDFd, %) and degradability of organic matter (OMd, %); dry matter intake (DMI, kg/d); urea in buffer (%); fluid passage rate (FF, L/d); total protozoa count (PZ, cells/mL); and methane production (CH4, mmol/d). A frequentist network (ELN) derived using a graphical LASSO (least absolute shrinkage and selection operator) technique with tuning parameters selected by Extended Bayesian Information Criteria (EBIC) and a BLN were constructed from these data. The illustrated associations in the ELN were unidirectional yet assisted in identifying prominent relationships within the rumen that were largely consistent with current understanding of fermentation mechanisms. Another advantage of the ELN approach was that it focused on understanding the role of individual nodes within the network. Such understanding may be critical in exploring candidates for biomarkers, indicator variables, model targets, or other measurement-focused explorations. As an example, acetate was highly central in the network suggesting it may be a strong candidate as a rumen biomarker. Alternatively, the major advantage of the BLN was its unique ability to imply causal directionality in relationships. Because the BLN identified directional, cascading relationships, this analytics approach was uniquely suited to exploring the edges within the network as a strategy to direct future work researching mechanisms of fermentation. For example, in the BLN acetate responded to treatment conditions such as the source of N used and the quantity of substrate provided, while acetate drove changes in the protozoal populations, non-NH3-N and residual N flows. In conclusion, the analyses exhibit complementary strengths in supporting inference on the connectedness and directionality of quantitative associations among fermentation variables that may be useful in driving future studies.

A newly developed bacteriocin like substance to replace monensin in diets of lactating ewes.

The aim of the present experiment was to evaluate the effect of feeding a newly produced bacteriocin-like substance (BLS) as a replacement formonensin in the diets of lactating ewes. In Experiment 1, the effects of BLS or monensin at 0.5, 1, 1.5, and 2g/kg diet on in vitro ruminal fermentation were compared. In Experiment 2, 30 multiparous Barki ewes were divided into three treatments in a complete randomized design for 90 days. The ewes were fed a basal diet without supplementation or supplemented with monensin or BLS at 0.5g/kg DM diet. In Experiment 1, the highest levels of BLS and monensin decreased gas production, while all levels of additives linearly decreased methane production. In Experiment 2, BLS increased nutrient digestibility. Additives increased ruminal total and individual volatile fatty acids and decreased ruminal ammonia-N. The BLS increased serum albumin and decreased the concentrations of serum liver enzymes, while both additives increased serum glucose and decreased urea-N. Additives increased daily production of milk, while the BLS treatment increased the feed efficiency. It is concluded that dietary inclusion of BLS at 0.5g/kg DM for lactating ewes is recommended to replace monensin.

Accumulation of Volatile Fatty Acids from Hydrothermally Treated Strawberry Extrudate through Anaerobic Fermentation at Different pH Values

The accumulation of volatile fatty acids (VFAs) through the anaerobic fermentation of organic waste, such as strawberry extrudate, is proposed for this work. A hydrothermal treatment was carried out, and it was proposed to break the complex matrix of the strawberry extrudate to favour the hydrolysis stage of the anaerobic digestion process. The production of volatile fatty acids from treated and untreated strawberry was evaluated by adjusting the pH to 5 and 9. After the hydrothermal treatment of the strawberry extrudate, an increase in the solubilisation of organic matter, such as sugars and phenols, was observed. In the production of VFAs by means of anaerobic digestion of the pretreated strawberry extrudate, a significant increase in the accumulation of volatile fatty acids was demonstrated at a pH of 9 with respect to the untreated strawberry extrudate. In addition, the operational pH also had a strong effect on the individual VFA profile. A stream enriched in acetic acid was obtained at a pH of 9 (around 65% of the VFAs), whereas the operation at a pH of 5 resulted in a more complex composition with a high percentage of propionic acid (29% of the VFAs).

Partial replacement of canola meal with dried dairy waste as a protein source in the diet of dairy cow: Effects on lactation performance, ruminal measurements, nutrient digestibility, and nitrogen balance

The potential nutritive values and in vivo responses of dried dairy waste (DDW) as a protein substitution for canola meal (CM) in the diet of early lactating Holstein dairy cows were evaluated. Twenty-four dairy cows were assigned to three treatments in a complete randomized design with eight replicates for 35 days. The treatments consisted of a control (without DDW), a low level of DDW (50% of dietary CM content was replaced by DDW), and a high level of DDW (100%). Dry matter intakes averaged 26.9 and 24.9 kg per day for control and DDW supplemented diets. Cows showed similar total-tract digestibility values for dry matter, organic matter, neutral detergent fiber, and ether extract. Ruminal pH and individual volatile fatty acids were not affected by the inclusion of DDW. There were no significant differences among the treatments for raw milk, fat, or energy corrected milk, as well as milk fat and protein yield by dietary replacement of CM with DDW. When compared to the control, feeding DDW enhanced feed efficiencies determined using raw milk and milk that has had its fat or calorie content adjusted. As the quantity of dietary DDW increased, urinary urea-N (g/d) decreased. Reduced urinary urea and manure nitrogen excretion are based on reduced dry matter intake, and 0.42 kg less crude protein intake when DDW replaced CM. DDW, as an alternative available protein source, could replace 50% of dietary CM. If milk production is maintained, DDW may be an eco-friendly supplement in lactating dairy cows by reducing feed and crude protein intake.