Volatile Fatty Acid Profile Research Articles

Kinetic investigations into the effect of inoculum to substrate ratio on batch anaerobic digestion of simulated food waste

This anaerobic digestion (AD) study investigated the effect of inoculum to substrate ratio (ISR 4.00 to 0.25) on viability of methanogenesis using simulated food waste as substrate. Given the complexity of the AD process, this study considered the interdependency of AD parameters and their effect on biogas production, as the digestion progressed. Maximum methane production was between ISR 2.00 (139 ± 10 ml CH4/g VS added) and 1.00 (152 ± 12 ml CH4/g VS added); further decreases in ISR were found to result in system acidification. Under acidogenic conditions (ISR≤0.5) pH and the volatile fatty acid (VFA) profile were found to be strongly dependent on the ISR. In contrast to ISR 0.25, ISR 0.50 showed reverse beta oxidation, which resulted in increased concentrations of medium chain VFAs over the digestion period. Maximum total VFA (TVFA) concentrations that the system could survive with reversible acidification (ISR 1.00) was found to be 17.52 ± 0.02 g/l, whereas the maximum TVFA production was found to be 29.25 ± 0.73 g/l for ISR 0.50. Uniquely, this study also reports up to 55% anaerobic degradation of lignin in acidified reactors with ISR 0.25, which based on existing literature, points towards the involvement of specific bacterial strains.

Nutritional, Physicochemical, and Endogenous Enzyme Assessment of Raw Milk Preserved under Hyperbaric Storage at Variable Room Temperature.

Raw milk (a highly perishable food) was preserved at variable room temperature (RT) under hyperbaric storage (HS) (50-100 MPa) for 60 days and compared with refrigeration (RF) under atmospheric pressure (AP) on quality, nutritional, and endogenous enzyme activity parameters. Overall, a comparable raw milk preservation outcome was observed between storage under AP/RF and 50/RT after 14 days, with similar variations in the parameters studied indicating milk degradation. Differently, even after 60 days (the maximum period studied) under 75-100/RT, a slower milk degradation was achieved, keeping most of the parameters similar to those of milk prior to storage, including pH, titratable acidity, total solid content, density, color, viscosity, and volatile organic and fatty acid profiles, but with higher free amino acid content, signs of an overall better preservation. These results indicate an improved preservation and enhanced shelf life of raw milk by HS/RT versus RF, showing HS potential for milk and highly perishable food preservation in general.

Co-production of Biohydrogen and Biomethane from Chicken Manure and Food Waste in a Two-Stage Anaerobic Fermentation Process.

Batch experiments were performed to evaluate the biohydrogen and biomethane production by co-digestion of chicken manure and food waste in a two-stage mesophilic fermentation process. Results showed that no hydrogen was produced in the first stage of sole chicken manure fermentation, while methane yield was 247.3 mL·g-1-VS. By comparison, the co-digestion process with food waste proportions of 50-85% obtained hydrogen yields of 15.5-57.5 mL·g-1-VS, and the methane yields and maximum specific methane production rates were also improved by 7.0-16.7% and 80%, respectively. Moreover, the highest hydrogen and methane yields were achieved during sole food waste fermentation process. The acetate was the main volatile fatty acid (VFA) produced during sole chicken manure fermentation process in the first stage. Statistical analysis revealed that hydrogen production from co-digestion process and sole food waste fermentation process followed the n-butyrate-type pathway. Meanwhile, it should be noticed that the co-fermentation of chicken manure and food waste had antagonistic effects on the hydrogen fermentation, implying that there might be some inhibition factors existing in chicken manure or produced during the co-fermentation process. At the beginning of methane fermentation, the VFA profiles were similar to those at the end of hydrogen fermentation, and the main VFA compositions changed to acetate and propionate in the latter period of methane production. The volatile solid removal efficiencies were also promoted in co-digestion process compared with sole chicken manure digestion, which were increased by 9.7-14.4% with food waste proportions of 50-80%.

Effect of Alpha-lipoic Acid on Productive Parameters and Ruminal VFA Profile in Sheep

Aims: The objective of this study was to evaluate the effect of alpha-lipoic acid (ALA) on feed over the productive parameters of sheep, as well as volatile fatty acids (VFA) in the rumen and blood glucose.
 Place and Duration of Study: The experiment was conducted at the Centro de Enseñanza, Investigación y Extensión en Producción Animal del Altiplano (CEIEPAA), located in Tequisquiapan, Querétaro-México.
 Methodology: A total of 64 sheep (Pelibuey x Dorset), two months old (32 males and 32 females with an average weight of 20.7 ± 1.3 kg) were used. Animals were housed in 16 pens, 4 animals per pen, and each pen was assigned to one of the 4 ALA inclusion treatments (0, 40, 80, 120 ppm). ALA was mixed with 50 g of ground corn to ensure its consumption; the animals of treatment 0 also received 50 g of ground corn without ALA.
 Results: Differences in weight gain were observed from day 56 in the animals supplemented with 80 ppm of ALA (P < .0001) and an improvement in daily weight gain (246 g) and feed conversion (P = .05) was shown. Animals treated with 40 ppm of ALA observed lower blood glucose without affecting the productive parameters (P = .05). A lower concentration of VFA was found in the treatment 120 ppm on day 84 (334.2 ± 26.5 vs 260.0 ± 15.7; P = .05).
 Conclusion: The inclusion of 80 ppm of ALA in the diet of sheep could improve the productive parameters.

Simultaneous production of hydrogen-methane and spatial community succession in an anaerobic baffled reactor treating corn starch processing wastewater

Corn starch processing wastewater (CSPW) is a high-strength organic wastewater and biological treatment is considered as the dominant process. The present work investigated the effects of pH on the bioenergy production and spatial succession of microbial community in an anaerobic baffled reactor (ABR) treating CSPW. The results showed that above 90.5% of COD removal and above 16.6 L d−1 of methane were achieved at the influent pHs of 8.0 and 7.0 under organic loading rate of 4.0 kg COD·m−3·L−1 condition. Further decreasing the influent pH to 6.0 resulted in the COD removal decreased to 89.7%. Besides, 9.2 L d−1 of hydrogen and 13.0 L d−1 of methane were obtained. There was significant difference in the volatile fatty acids profiles during the variation of pH. Illumina Miseq sequencing showed that Clostridium, Ethanoligenens, Megasphaera, Prevotella and Trichococcus with relative abundance of 2.1%∼28.1% were the dominant hydrogen-producing bacteria in C1. Methanogens (Methanothrix and Methanobacterium) dominated in the last three compartments. Function predicted analysis revealed that the abundance of metabolic-related gene families containing carbohydrate, amino acids and energy in the last three compartments were higher than that in C1. A deduced biodegradation model of CSPW in ABR revealed that the anaerobic sludge in C1 mainly produced hydrogen. Microbial population in C3 was responsible for COD removal and methane production. The redundancy analysis revealed that hydrogen production was highly correlated with some hydrogen-producing bacteria in C1, whereas methane production was positively correlated with microbial group in C2∼ C4.

Changes in Ileum and Cecum Volatile Fatty Acids and Their Relationship with Microflora and Enteric Methane in Pigs Fed Different Fiber Levels

Mustard and grapeseed meals are low-cost by-products generated by the oil industry. We aimed to investigate the effects of fiber level on the concentration of volatile fatty acids (VFAs) in the ileum and cecum, as well as the microflora and enteric methane (E-CH4) in pigs. A total of 70 Topigs hybrid pigs, 56 ± 3 days old, 20.96 ± 0.26 kg live weight, were randomly allotted to two feeding groups: (i) SM diet based on sunflower meal; (ii) MG diet based on mustard × grapeseed oil meals (MG-mixt). VFA profiles were determined by gas chromatography. E-CH4 was calculated using our trial data along with prediction equations. The MG-mixt slightly decreased growth parameters but improved daily feed efficiency and gain cost. The MG diet increased the concentration of VFAs and the microflora level. The higher VFA level recorded in the cecum (+53.93%) was correlated with a lower pH level (Spearman correlation coefficient, rho = −0.529, p < 0.001). In relation to DM intake and energy retention, E-CH4 recorded a highly significant decline in the MG group (<9.42%). A strong relationship was recorded among VFAs, microflora, predicted E-CH4, and fiber and NDF intake. The VFAs could be predictors for the E-CH4 level (p < 0.001). A significant relationship between E-CH4 and total VFAs was noted (rho = −0.462, p = 0.04). We conclude that MG-mixt has the potential to replace sunflower meal, with the minor drawbacks being balanced by the advantages provided in terms of feed efficiency, E-CH4 mitigation, and VFA levels.

Evaluation of in vitro energy distribution and methanogenic potential of two forages with the addition of condensed tannins

The objective of this work was to analyze the effect of the addition of condensed tannins (CT) in the efficiency of digestion, methanogenic potential and energy distribution between the fermentation products of two forages. An assay was carried out using the in vitro gas production technique in which extracts of Quebracho (Schinopsis balansae) and Lotus corniculatus were evaluated with fermentation patterns of derived products from Ryegrass (RG, Lolium perenne) and a tropical forage, Megathyrsus maximus (MM). Tannins were added to the substrate at a concentration of 30 mg g-1. MM presented higher and delayed gas production (GP), and in vitro dry matter, organic matter and fiber digestibilities (ivDMD, ivOMD and NDFD, respectively) were relatively high but lower than RG. In addition, MM presented higher CH4 production (CH4p) than RG in 24 and 48h. Even though CT of Quebracho induced a decrease in the NDFD, contrary to what was expected, CH4p was greater, although this effect could not be attributed to the presence of CT. The stoichiometric evaluation indicated that while the highest CH4p in Quebracho treatments were associated with acetogenic profiles, CH4p with Lotus did not show any relationship with the volatile fatty acids (VFA) profile, but it did show a relationship with the highest total VFA production and the highest GP.

EFECTO DE DIFERENTES ESTRATEGIAS DE PRETRATAMIENTO FÍSICO EN LA BIODEGRADABILIDAD DE MATERIALES LIGNOCELULÓSICOS

When lignocellulosic biomass is used as a substrate in anaerobic digestion processes, a pretreatment stage is always required to break the hard structure of the material and facilitate the attack of microorganisms and, with it, their degradation. Numerous methods have been developed to pretreat lignocellulosic biomass. Four of them: torrefaction, cavitation, pelletizing and extrusion have been comparatively evaluated in this article as ways to increase methane production through anaerobic digestion of two raw materials with different lignin content: barley straw and vine shoot. In addition, it was examined how these pretreatments and the nature of the feedstock influence the volatile fatty acid profiles that are generated during the digestion process. The cavitation of biomass milled at 0.25 mm was revealed as the most efficient pretreatment among those tested, increasing by 360% and 240%, respectively, the methane production for vine shoots and barley straw.

Feeding System Effects on Dairy Cow Rumen Function and Milk Production.

Simple SummaryIn ruminants, diet has a significant effect on rumen function. Hence, this study was conducted to see if changing the normal grass-based diet of cows could change rumen function and milk production. Therefore, we compared three diets: Grass (cows grazing grass-only), Grass-Clover (cows grazing grass-white clover only) and cows fed a total mixed ration (TMR) diet indoors. We monitored the cows over the course of a full lactation cycle in a spring-calving system. In order to examine rumen function, some of the cows had a cannula placed in their rumen so that we could collect rumen contents samples. After we collected the samples and analysed the data we found that the type of diet the cows were offered did significantly affect milk production; milk yield and milk solids yield were generally highest on the TMR diet. When we looked at the rumen sample data we found that diet also affected rumen function; it altered the rumen volatile fatty acid (VFA), and ammonia and lactic acid profiles significantly but did not effect on rumen pH. Clover inclusion in the diet led to higher total rumen VFA and ammonia concentrations and higher milk urea nitrogen compared to the grass and TMR diets. We suggest this indicates a higher protein intake on that diet. Given these findings, we concluded that a clover-based diet could significantly alter rumen function, milk composition and milk yield in dairy cows.Good rumen function, which is largely influenced by the diet of the cow, is essential to optimise animal performance. This study, conducted over the course of a full lactation in a spring-calving milk production system, compared the rumen function and milk production of cows offered one of three dietary treatments: (1) Cows grazing grass-only swards receiving 250 kg nitrogen (N)/ha/year (Grass), (2) Cows grazing grass-white clover swards receiving 250 kg N/ha/year (Grass-Clover), and (3) Cows offered a total mixed ration diet and housed indoors (TMR). Treatment significantly affected milk production; milk yield and milk solids yield were generally highest on the TMR treatment. There was no effect of treatment on rumen pH. However, treatment significantly altered the rumen volatile fatty acid (VFA), and ammonia and lactic acid profiles. Clover inclusion in the sward led to higher (p < 0.05) total VFA and ammonia concentrations compared to the Grass and TMR treatments. The increased rumen ammonia concentration was associated with a significantly greater milk urea nitrogen (MUN) content in the milk from cows fed on Grass-Clover, indicating a greater excess of dietary protein in that treatment. It was concluded that a clover-based dairy cow feeding system could significantly alter rumen function, milk composition and milk yield.

Prevailing acid determines the efficiency of oleaginous fermentation from volatile fatty acids

Microbial lipids are envisaged as promising alternatives for sustainable production of chemicals and fuels. Although sugar-based substrates are the most conventional carbon sources employed for this purpose, the use of low-cost feedstock, such as organic wastes, is crucial for an economically-viable process. In this study, volatile fatty acids (VFAs) obtained during the anaerobic fermentation of food waste were used as carbon sources to produce lipids in Yarrowia lipolytica ACA DC 50109. Different total VFAs concentrations, acids profiles and carbon:nitrogen (C:N) ratios were used in both real digestates and synthetic media to establish the optimal culture conditions for lipid production. Y. lipolytica was able to grow in all cases despite of using concentrations as high as 15 g/L of total VFAs. The highest obtained lipid contents were 43.4% and 37.3% w/w using 15 g/L VFAs, 6:1 acetic:hexanoic ratio and C:N of 200:1 and 150:1, respectively. These lipids contents implied lipid yields of 0.33 g/g and 0.31 g/g, that were very close or even higher than lipid yields reported from sugars. This fact proves the suitability of using VFA derived from wastes as a low-cost carbon sources for the production of lipids and highlights the importance of paying attention to VFAs profile and C:N in the media for an efficient process.

Effect of Hydrogen Peroxide on Hydrogen Production from Melon Fruit (Cucumis melo L.) Waste by Anaerobic Digestion Microbial Community

Biohydrogen (H2) production has the potential to provide clean, environmentally friendly, and cost-effective energy sources. The effect of increasing oxidative stress on biohydrogen production by acid-treated anaerobic digestion microbial communities was studied. The use of varying amounts of hydrogen peroxide (H2O2; 0.1, 0.2, and 0.4 mM) for enhancing hydrogen production from melon fruit waste was investigated. It was found that H2O2 amendment to the H2-producing mixed culture increased hydrogen production. Treatment with 0.4 mM H2O2 increased cumulative H2 output by 7.7% (954.6 mL/L), whereas treatment with 0.1 mM H2O2 enhanced H2 yield by 23.8% (228.2 mL/gVS) compared to the untreated control. All treatments showed a high H2 production rate when the pH was 4.5 – 7.0. H2O2-treated samples exhibited greater resilience to pH reduction and maintained their H2 production rate as the system became more acidic during H2 fermentation. The application of H2O2 affected the volatile fatty acid (VFA) profile during biohydrogen fermentation, with an increase in acetic and propionic acid and a reduction in formic acid concentration. The H2O2 treatment positively affects H2 production and is proposed as an alternative way of improving H2 fermentation.

In vitro Inoculation of Fresh or Frozen Rumen Fluid Distinguishes Contrasting Microbial Communities and Fermentation Induced by Increasing Forage to Concentrate Ratio.

In vitro rumen batch culture is a technology to simulate rumen fermentation by inoculating microorganisms from rumen fluids. Although inocula (INO) are commonly derived from fresh rumen fluids, frozen rumen fluids are also employed for the advantages of storing, transporting, and preserving rumen microorganisms. The effects of frozen INO on microbial fermentation and community may be interfered with by substrate type, which has not been reported. This study was designed to test whether rumen fluid treatments (i.e., fresh and frozen) could interact with incubated substrates. A complete block design with fractional arrangement treatment was used to investigate the effects of INO (fresh or frozen rumen fluids) and concentrate-to-forage ratios (C/F, 1:4 or 1:1) on rumen fermentation and microbial community. The effects of increasing C/F were typical, including increased dry matter (DM) degradation and total volatile fatty acids (VFA) concentration (P < 0.001), and decreased acetate to propionate ratio (P = 0.01) and bacterial diversity of richness and evenness (P ≤ 0.005) with especially higher fermentative bacteria such as genus Rikenellaceae_RC, F082, Prevotella, Bacteroidales_BS11, Muribaculaceaege, and Christensenellaceae_R-7 (P ≤ 0.04). Although frozen INO decreased (P < 0.001) DM degradation and altered rumen fermentation with lower (P ≤ 0.01) acetate to propionate ratio and molar proportion of butyrate than fresh INO, typical effects of C/F were independent of INO, as indicated by insignificant INO × C/F interaction on substrate degradation, VFA profile and bacterial community (P ≥ 0.20). In summary, the effect of C/F on fermentation and bacterial diversity is not interfered with by INO type, and frozen INO can be used to distinguish the effect of starch content.

The capture technology matters: Composition of municipal wastewater solids drives complexity of microbial community structure and volatile fatty acid profile during anaerobic fermentation

The production of volatile fatty acids (VFAs) represents a relevant option to valorize municipal wastewater (MWW). In this context, different capture technologies can be used to recover organic carbon from wastewater in form of solids, while pre-treatment of those solids has the potential to increase VFA production during subsequent fermentation. Our study investigates how VFA composition produced by fermentation is influenced (i) by the choice of the capture technology, as well as (ii) by the use of thermal alkaline pre-treatment (TAP). Therefore, the fermentation of solids originating from a primary settler, a micro-sieve, and a high-rate activated sludge (HRAS) system was investigated in continuous lab-scale fermenters, with and without TAP. Our study demonstrates that the capture technology strongly influences the composition of the produced solids, which in turn drives the complexity of the fermenter's microbial community and ultimately, of the VFA composition. Solids captured with the primary settler or micro-sieve consisted primarily of polysaccharides, and led to the establishment of a microbial community specialized in the degradation of complex carbohydrates. The produced VFA composition was relatively simple, with acetate and propionate accounting for >90% of the VFAs. In contrast, the HRAS system produced biomass-rich solids associated with higher protein contents. The microbial community which then developed in the fermenter was therefore more diversified and capable of converting a wider range of substrates (polysaccharides, proteins, amino acids). Ultimately, the produced VFA composition was more complex, with equal fractions of isoacids and propionate (both ~20%), while acetate remained the dominant acid (~50%). Finally, TAP did not significantly modify the VFA composition while increasing VFA yields on HRAS and sieved material by 35% and 20%, respectively. Overall, we demonstrated that the selection of the technology used to capture organic substrates from MWW governs the composition of the VFA cocktail, ultimately with implications for their further utilization.

Ruminal profile of completed feed as influenced by myristic and tannins addition

The study aimed to determine the effect of adding tannin and myristic acid in complete feed on nutrient content and the Profile of volatile fatty acids (VFA) in vitro. The materials used for this research were corn straw, condensed tannins, myristic acid, coffee waste, rice bran, tapioca byproduct, soybean meal, copra meal, and palm kernel meal. The method was used in this experiment was laboratory experiment with four treatments and three replications. The treatment consisted of T1 complete feed (40% corn straw + 60% concentrate (be based DM)), T2 (complete feed + condensed tannins 3%/kg DM and myristic acid 2%/kg DM), T3 (complete feed + condensed tannins 3%/kg DM and myristic acid 3%/kg DM), and T4 (complete feed + condensed tannins 3%/kg DM and myristic acid 4%/kg DM). Every treatment was repeated three times and analysed statistically using Randomized Block Design (RBD). The adding of 4% myristic acid to the complete feed (T4) gives the best results, it increased nutrition and propionic acid, but decreased acetic acid, butyric acid, total VFA and C2/C3 ratio.

Dried distiller´s grains plus solubles supplementation improves low-quality tropical grass utilization on beef steers

ABSTRACT: This study was designed to evaluate the effect of corn dried distiller´s grains (DDGS) supplementation on feed intake, total tract digestibility, and ruminal fermentation of beef steers fed low-quality Guinea grass (Megathyrsus maximus, cv. Gatton panic). Twelve Braford crossbred steers were housed in individual pens (n = 4 steers/treatment), provided with three levels of DDGS supplement: 0%, 0.6%, or 1.2% BW. Steers were blocked by live weight and randomly assigned to treatments within the block. Corn DDGS supplementation increased total OM intake (21.55, 40.23, and 56.69 g/kg BW0.75) and tract OM digestibility (46.33, 49.03, and 72.39 % DM). Total tract digestible OM, CP, NDF and EE intake also increase in response to DDGS supplementation. Forage OM intake decreased when supplementation level reached 1.2 % BW. Also, ruminal pH decreased with DDGS supplementation level (6.88, 6.47, and 6.27). No differences were observed in total volatile fatty acids (VFA) concentration; however, the molar proportion of acetate decreased (77.98, 73.90, and 67.29 % Total VFA) as well as acetate: propionate ratio (4.38, 3.48, and 2.74). On the contrary, propionate proportions increased (18.32, 21.86, and 24.81 % Total VFA). Levels of ammonia and lactate were within suggested values for optimal fermentation and bacterial growth. Low-quality grass supplementation with corn DDGS increased total OM intake and digestibility. Also, DDGS inclusion favorably altered volatile fatty acids profile by reducing the acetate to propionate ratio regarding forage-only diets.

Influence of the total concentration and the profile of volatile fatty acids on polyhydroxyalkanoates (PHA) production by mixed microbial cultures

Polyhydroxyalkanoates (PHAs) production from lignocellulosic biomass using mixed microbial cultures (MMC) is a potential cheap alternative for reducing the use of petroleum-based plastics. In this study, an MMC adapted to acidogenic effluent from dark fermentation (DF) of exhausted sugar beet cossettes (ESBC) has been tested in order to determine its capability to produce PHAs from nine different synthetic mixtures of volatile fatty acids (VFAs). The tests consisted of mixtures of acetic, propionic, butyric, and valeric acids in the range of 1.5–9.0 g/L of total acidity and with three different valeric:butyric ratios (10:1, 1:1, and 1:10). Experimental results have shown a consistent preference of the MMC for the butyric and valeric acids as carbon source instead other shorter acids (propionic or acetic) in terms of PHA production yield (estimated in dry cell weight basis), with a maximum value of 23% w/w. Additionally, valeric-rich mixtures have demonstrated to carry out a fast degradation process but with poor final PHA production compared with high butyric mixtures. Finally, high initial butyric and valeric concentrations (1.1 g/L and 4.1 g/L) have demonstrated to be counterproductive to PHA production.

The effect of refining process on the volatile compounds, oxidation stability and fatty acids profile of soybean oil using an electrostatic field

The effect of refining process on the volatile compounds, oxidation stability and fatty acids profile of soybean oil using an electrostatic field

Influence of feedstock mix ratio on microbial dynamics during acidogenic fermentation for polyhydroxyalkanoates production

The nature of microbial populations plays an essential role in the production of volatile fatty acids (VFA) during acidogenesis, the first stage in polyhydroxyalkanoates (PHA) production using mixed cultures. However, the composition of microbial communities is generally affected by substrate alterations. This work aimed to unravel the microbial dynamics in response to a gradual change in the feedstock composition in an acidogenic reactor, with subsequent PHA production. To achieve this, co-digestion of cheese whey and brewery wastewater (BW) was carried out for the production of VFA, in which the ratio of these feedstocks was varied by gradually increasing the proportion of BW from 0 up to 50% of the organic content. Bacteria such as Megasphaera, Bifidobacterium or Caproiciproducens were the most abundant in the first stages of the co-digestion. However, when BW reached 25% of the organic load, new taxa emerged and displaced the former ones; like Selenomonas, Ethanoligenens or an undefined member of the Bacteroidales order. Accordingly, the production of butyric acid dropped from 52 down to 27%, while the production of acetic acid increased from 36 up to 52%. Furthermore, the gradual increase of the BW ratio led to a progressive drop in the degree of acidification, from 72 down to 57%. In a subsequent approach, the VFA-rich streams, obtained from the co-digestion, were used as substrates in PHA accumulation tests. All the tests yielded similar PHA contents, but with slightly different monomeric composition. The overall results confirmed that the microbiome was altered by a gradual change in the feedstock composition and, consequently, the VFA profile and the monomeric composition of the biopolymer also did.

Evaluation of microwave-dried black soldier fly (Hermetia illucens) larvae meal as a dietary protein source in broiler chicken diets

Here, the effect of microwave-dried black soldier fly (Hermetia illucens) larvae meal (HILM) as a dietary protein source on the growth performance and health of broilers was evaluated. A total of 126 male broilers were randomly allocated to three treatments (six replicates of seven birds per group): control diet (CON) of corn and soybean meal and two experimental diets in which soybean meal was replaced with 25% (25HILM) or 50% (50HILM) HILM. The broilers were slaughtered at 35 d to determine the apparent ileal digestibility (AID), volatile fatty acid (VFA) profiles, and length and weight of the small intestine. Blood samples were collected from 36 randomly selected birds (12 broilers per treatment) to determine serum parameters and haematological traits. Average daily gain, feed intake, and AID of protein were decreased (P&lt;0.05) in the 50HILM group compared with those in the CON group. Dietary HILM increased (P&lt;0.05) the relative length of the entire digestive tract and total VFAs in the caecal digesta. Serum low-density lipoprotein cholesterol was the lowest (P&lt;0.01), but the triglyceride levels were the highest (P&lt;0.05) in the 50HILM group. The serum phosphorus level was lower in both HILM diet-fed groups (P&lt;0.01), whereas the creatine phosphokinase level was lower in the 50HILM group than in the CON group. In contrast, the 50HILM group showed higher (P&lt;0.05) monocyte and red blood cell distribution width-standard deviation. In conclusion, dietary microwave-dried HILM positively influenced the VFA and cholesterol levels; however, growth performance was negatively affected by malnutrition caused by low protein digestibility in the 50HILM group. Microwave-dried HILM is a valuable ingredient for broiler diets, with up to 25% substitution showing no detrimental effects on growth performance and health. Further studies are needed to improve HILM digestibility.

328 The Potential Role of Two Red Seaweeds That Promote Anti-methanogenic Activity and Rumen Fermentation Profiles Under Laboratory Conditions

Abstract Ruminal methane (CH4) production results from carbohydrate fermentation by ruminal microbiota (methanogens) to produce CH4, volatile fatty acids (VFA), carbon dioxide (CO2), nitrous oxide (N2O), and hydrogen (H2) in a reduction pathway. The aims of this study were to assess the effects of two red seaweed (RSW) species (Asparagopsis taxiformis and A. armata; collected from Messina, Italy). The two RSW were identified by DNA barcoding and genetic data were deposited in BOLD Systems (REAPP006-21, REAPP004-21, respectively). The two RSW were used at dietary inclusion levels (0, 2, and 4% as-fed basis) in an anaerobic in vitro study (39°C for 48-h) to examine greenhouse gas (GHG) production and VFA profiles. Gases were collected using an ANKOM Gas Production system and analyzed for CH4 and N2O by gas chromatography. Asparagopsis taxiformis contained higher levels of bromoform (201 vs. 7.0 mg/kg DM), iodine (4820 vs. 3260 ppm), and crude protein (16 vs. 15.6% DM), than A. armata, which contained higher levels of acid detergent fiber (ADF; 7.7 vs. 19.0%) and neutral detergent fiber (NDF; 13.2 vs. 19.2%), respectively. RSW supplementation increased total gas, butyrate and valerate production (P &amp;lt; 0.01), while production of CH4 (mg/g DM), acetate (A), propionate (P), A/P ratios and in vitro dry matter digestibility (IVDMD; % DM) were reduced (P &amp;lt; 0.01) as RSW supplementation increased. In the presence of A. taxiformis, production of N2O (µg/g DM), tended to be less (P = 0.1) at 2% DM, but increased (P &amp;lt; 0.01) N2O production with A. armata at the 2 and 4% DM. Therefore, it may be possible to suppress methanogenesis both directly and indirectly by addition of RSW. To efficiently use seaweeds as feed ingredients with nutritional and environmental benefits, more research is required to determine the mechanisms underlying seaweed and dietary substrate interactions.