Ruminal Fermentation

A special issue of Fermentation (ISSN 2311-5637). This special issue belongs to the section "Microbial Metabolism, Physiology & Genetics".

Deadline for manuscript submissions: closed (31 March 2025) | Viewed by 12613

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Guest Editor
Department of Animal Science, Universidade Federal dos Vales do Jequitinhonha e Mucuri, Unaí, Brazil
Interests: alternative additives; antimicrobials; beef and dairy cattle; composition of ruminal microbiota; deamination; nitrogen metabolism
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Dear Colleagues,

The success of ruminant animals is associated with their ability to digest fiber-rich plant material. Although ruminants do not secrete digestive enzymes in the rumen, a number of various microorganisms, including bacteria, methanogenic archaea, anaerobic fungi, and protozoa, which live in symbiosis with the host, are capable of performing ruminal fermentation and hydrolyzing soluble and insoluble carbohydrates, proteins, and lipids from the diet.

Ruminal fermentation is the result of the balance of interactions among the different species of microorganisms present in the rumen. It is the outcome of microbiological activities responsible for converting food components (carbohydrates and nitrogen) into products used in animal metabolism, such as volatile organic acids (VOAs), microbial proteins, and B vitamins. This process also produces substances not utilized by the animal (CH4 and CO2), which are physiologically eliminated and represent energy losses.

The proportion and quantity of by-products resulting from the ruminal fermentation process depend on various factors, such as the type of feed, the manner in which the feed is offered, balanced diets, the use of feed additives, as well as physiological factors related to the ruminal environment, such as temperature, pH, and redox potential.

The aim of this Special Issue is to publish both recent innovative research results and review papers that assess ruminal fermentation both in vitro and in vivo using different strategies aimed not only at improving the health and performance of ruminants but also at playing a role in mitigating climate change by reducing ammonia production and greenhouse gas emissions, such as methane. If you would like to contribute a review paper, please contact one of the editors to discuss the topic's relevance before submitting the manuscript.

Prof. Dr. Cláudia Braga Pereira Bento
Guest Editor

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Keywords

  • ammoniacal nitrogen
  • animal nutrition
  • antimicrobials
  • enteric methane
  • environmental impact
  • feed additives
  • feed efficiency
  • next-generation sequencing
  • rumen parameters
  • ruminal microbiota
  • ruminants

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Related Special Issue

Published Papers (13 papers)

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Research

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11 pages, 797 KiB  
Article
Comparison of In Vitro Fermentation Characteristics Among Five Maize Varieties
by Fabio Zicarelli, Serena Calabrò, Piera Iommelli, Micaela Grossi, Federico Infascelli and Raffaella Tudisco
Fermentation 2025, 11(5), 285; https://doi.org/10.3390/fermentation11050285 - 15 May 2025
Viewed by 243
Abstract
Maize (Zea mays L.) silage in the irrigated and flat areas of Italy represents the most important large ruminant feed crop due to the high dry matter yield and nutritive value per hectare. The aim of the investigation was to evaluate the [...] Read more.
Maize (Zea mays L.) silage in the irrigated and flat areas of Italy represents the most important large ruminant feed crop due to the high dry matter yield and nutritive value per hectare. The aim of the investigation was to evaluate the chemical composition and the in vitro fermentation patterns of five maize varieties (Tiesto, R700 1, MAS 78.T, DKC 7074 and KWS Kantico) freshly chopped and preserved via ensiling. The results indicated that the chemical composition was not significantly different among varieties. The substrates were incubated for 72 h with buffered rumen fluid collected from cow. The ensiling process slightly reduced gas production and fermentation kinetics, likely due to the consumption of soluble sugars during fermentation. Organic matter loss (OM loss) differed significantly (p < 0.01) among varieties in ensiled maize, correlating with their neutral detergent fiber (NDF) content. While total volatile fatty acid (VFA) production showed no significant differences between varieties, the buffer capacity ratio (BCR), an indicator of protein degradation, varied significantly. Ammonia production (NH3) was significantly higher in ensiled samples, supporting previous findings that ensiling increases non-protein nitrogen (NPN) due to microbial proteolysis and plant enzyme activity. The gas production profiles and fermentation rates over time showed minor differences between fresh and ensiled samples, with fresh material exhibiting faster fermentation kinetics due to the presence of soluble sugars. These findings highlight the importance of evaluating maize silage quality to optimize ruminant nutrition and feed efficiency. Full article
(This article belongs to the Special Issue Ruminal Fermentation)
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16 pages, 1903 KiB  
Article
Species and Harvest Time of Fresh Tropical Grasses Affect Rumen Fermentation as Determined by In Sacco and In Vitro Incubations
by Huyen Thi Duong Nguyen, Jill Derix, Wouter Hendrikus Hendriks, Jan Thomas Schonewille, Trach Xuan Nguyen and Wilbert Frans Pellikaan
Fermentation 2025, 11(5), 276; https://doi.org/10.3390/fermentation11050276 - 12 May 2025
Viewed by 257
Abstract
The consumption of forages high in slow-degradable carbohydrates by dairy cattle leads to greater ruminal acetate production, which benefits milk fat content. Although tropical grasses are typically rich in fibrous materials, the milk fat content of dairy cows in Southeast Asia is low. [...] Read more.
The consumption of forages high in slow-degradable carbohydrates by dairy cattle leads to greater ruminal acetate production, which benefits milk fat content. Although tropical grasses are typically rich in fibrous materials, the milk fat content of dairy cows in Southeast Asia is low. Here, we investigate the effects of the species and harvest time of three common tropical grasses (Guinea, King, and Mulato II) harvested at three instances (early, normal, late) on in sacco degradation kinetics and in vitro gas production (IVGP) characteristics. Grass samples were subjected to (1) chemical analysis, (2) a fully automated in vitro gas recording system using rumen fluid to measure fermentation characteristics over 72 h, and (3) in sacco degradation using the nylon bag technique, employing seven incubation times up to 336 h. Forage quality decreased with maturity, as reflected in changes to digestibility and fiber content. Overall, early harvested grasses yielded the highest total gas production (311 ± 12.5 mL/g OM) followed by normal (300 ± 45.7 mL/g OM) and late (273 ± 19.5 mL/g OM) harvested grasses. The in vitro fermentable fraction (A1 + A2) was the highest for early harvested grasses, with the A2 parameter, relevant for milk fat content, being the highest for Guinea (81.6% A2/(A1 + A2)) and the lowest for King grass (71.0% A2/(A1 + A2)). Consequently, early harvested Guinea had the longest incubation times (10.5 h) and lowest fermentation rates (Rmax2 = 12.8 mL/g OM/h). Regression analysis showed relationships between NDF content and degradability. Harvesting tropical grass earlier than customarily practiced enhanced forage quality and ruminal degradability. Of the three grasses studied, each at three levels of maturity, early harvested Guinea grass was the most promising candidate for improving milk fat content in Southeast Asian dairy cows. This grass showed a high fermentable OM content, with a large proportion of slow-degradable carbohydrates. Full article
(This article belongs to the Special Issue Ruminal Fermentation)
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18 pages, 5172 KiB  
Article
Can Ammonium Nitrate Be a Strategic Tool by Replacing Urea as a Nitrogen Supplementation Source to Beef Cattle in Intensified Grazing Systems?
by Willian Rufino Andrade, Analisa Vasques Bertoloni, Flavio Perna Junior, Althieres José Furtado, Ana Laura Januário Lelis, Murilo Trettel, Alexandre Berndt, Patricia Perondi Anchão Oliveira, Angélica Simone Cravo Pereira and Paulo Henrique Mazza Rodrigues
Fermentation 2025, 11(5), 261; https://doi.org/10.3390/fermentation11050261 - 6 May 2025
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Abstract
For cattle raised on tropical grass pastures, it is essential to explore strategies that circumvent climatic seasonality that affect forage availability and quality. We hypothesize that the intensification of grazing systems, with rotational and deferred methods, combined with ammonium nitrate or urea supplementation, [...] Read more.
For cattle raised on tropical grass pastures, it is essential to explore strategies that circumvent climatic seasonality that affect forage availability and quality. We hypothesize that the intensification of grazing systems, with rotational and deferred methods, combined with ammonium nitrate or urea supplementation, are excellent strategies to increase ruminal efficiency and animal productivity. For this purpose, 8 cattle with cannulas were distributed in rotational and deferred grazing systems, supplemented with urea or ammonium nitrate, and evaluated throughout the four seasons of the year over a period of two years. Dry matter intake and digestibility were measured using indigestible neutral detergent fiber, titanium dioxide and chromium oxide markers. Ruminal kinetics and degradability of DM and nutrients were measured using the nylon bag technique. Urine parameters were used to estimate microbial nitrogen compounds synthesis and efficiency of microbial protein synthesis. The rotational grazing improves NPN intake, NDF and ADF digestibility, and gross energy. Ammonium nitrate supplementation showed improved efficiency in microbial protein synthesis without negatively affecting feed intake, positioning it as a valuable nitrogen source for grazing cattle. Full article
(This article belongs to the Special Issue Ruminal Fermentation)
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11 pages, 1850 KiB  
Article
Effects of Different Levels of Thiamine Diphosphate on In Vitro Methane Reduction and Fermentation Characteristics of Korean Native Cow (Hanwoo)
by Seong-Shin Lee, Seong-Uk Jo, Heoyn-Sang Kim, Ji-Soo Wi, Yoo-Kyung Lee and Seong-Dae Lee
Fermentation 2025, 11(5), 247; https://doi.org/10.3390/fermentation11050247 - 1 May 2025
Viewed by 278
Abstract
This study investigated the effects of different doses of thiamine diphosphate (ThDP) on methane reduction and fermentation characteristics of Korean native cow (Hanwoo). In vitro trials used ThDP powder at 240, 360, 480, 600, and 720 ppm of substrate, with each sample incubated [...] Read more.
This study investigated the effects of different doses of thiamine diphosphate (ThDP) on methane reduction and fermentation characteristics of Korean native cow (Hanwoo). In vitro trials used ThDP powder at 240, 360, 480, 600, and 720 ppm of substrate, with each sample incubated at 39 °C for 24 and 48 h. After incubation, each sample was analyzed for total gas, methane production, dry matter digestibility, and rumen fermentation characteristics. Mean comparisons were performed using Tukey’s test, with significant differences declared at p < 0.05. Total gas production, methane ratio, and methane production per digested dry matter had a quadratic pattern (p < 0.001), and the 480 ppm treatment had the lowest (p < 0.05) at 24 and 48 h of incubation. Total volatile fatty acid concentration showed no significant difference at 24 h but differed significantly at 48 h (p > 0.05). The concentration of propionate had a quadratic pattern (p < 0.001), and the 480 ppm treatment showed the highest levels compared to the other treatments (p < 0.05) after 24 and 48 h of incubation. In conclusion, ThDP supplementation had a methane inhibition effect. In particular, the methane inhibition effect was most pronounced when ThDP was supplemented at 480 ppm. Full article
(This article belongs to the Special Issue Ruminal Fermentation)
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14 pages, 1025 KiB  
Article
Comparison of Effects of Cold and Warm Water Intake in Winter on Growth Performance, Thermoregulation, Rumen Fermentation Parameters, and Microflora of Wandong Bulls (Bos taurus)
by Jing Li, Zhihao Cui, Ming Wei, Chunqing Yin and Peishi Yan
Fermentation 2025, 11(3), 132; https://doi.org/10.3390/fermentation11030132 - 8 Mar 2025
Viewed by 659
Abstract
Efficient farm practices are crucial for livestock health and performance, and cold stress is a major challenge for cattle in winter. This study aimed to preliminarily investigate the effects of cold and warm water intake in winter on the growth performance, thermal stress [...] Read more.
Efficient farm practices are crucial for livestock health and performance, and cold stress is a major challenge for cattle in winter. This study aimed to preliminarily investigate the effects of cold and warm water intake in winter on the growth performance, thermal stress indicators, serum hormones and metabolites, rumen fermentation parameters, rumen fiber degrading enzyme, and rumen microflora of yellow cattle during winter. Eight Wandong Bulls (Bos taurus) were divided into two groups: group C, which received cold water (6.36 ± 1.99 °C), and group E, which received warm water (32.00 ± 3.12 °C) for 30 d. The results showed that warm water intake significantly increased ADG (p = 0.024) and DMI (p = 0.046) and decreased (p = 0.047) the ratio of feed intake to weight gain. Furthermore, the heat production, respiratory rate, surface temperature, and rectal temperature of cattle did not alter with water temperature, but the heat production value of the bulls increased (29.64 vs. 25.76 MJ/W0.75 h−1) with cold water intake compared to warm water. The concentrations of thyroxine (p = 0.021), serum urea nitrogen (p = 0.025), and glucose (p = 0.011) increased for the bulls drinking cold water compared to those drinking warm water. The concentrations of NH3-N (p = 0.048), total VFA (p = 0.010), acetate (p = 0.009), propionate (p = 0.009), cellulase (p < 0.01), and xylanase (p < 0.05) were lower in group C compared to group E. Total bacterial abundance, as well as specific species including Ruminococcus flavus, Ruminococcus albus, and Prevotella ruminicola, were lower (p < 0.05) in group C compared to group E. In conclusion, drinking warm water during winter enhanced growth performance by influencing energy metabolism, regulating serum hormones and metabolites, and modulating ruminal microflora of bulls compared to cold water intake. Full article
(This article belongs to the Special Issue Ruminal Fermentation)
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13 pages, 300 KiB  
Article
Enhancing Rumen-Undegradable Protein via Processing Techniques in a Dual-Flow Continuous Culture System
by K. E. Loregian, M. J. Silva, S. B. Dourado, J. Guimarães, B. R. Amâncio, E. Magnani, T. H. Silva, R. H. Branco, P. Del Bianco Benedeti and E. M. Paula
Fermentation 2025, 11(2), 94; https://doi.org/10.3390/fermentation11020094 - 12 Feb 2025
Viewed by 1066
Abstract
The use of processing techniques to increase the rumen-undegradable protein (RUP) content of protein meals aims to enhance the nutritional performance of high-performance animals. This study evaluated the effects of various processing techniques applied to peanut and cottonseed meals on ruminal parameters using [...] Read more.
The use of processing techniques to increase the rumen-undegradable protein (RUP) content of protein meals aims to enhance the nutritional performance of high-performance animals. This study evaluated the effects of various processing techniques applied to peanut and cottonseed meals on ruminal parameters using a dual-flow continuous culture system. These two feeds were individually analyzed in two experiments, each one using five fermenters (1297 ± 33 mL) in a 5 × 5 Latin square arrangement with five periods of 10 d each, with 7 d for diet adaptation and 3 d for sample collections. Five treatments were evaluated in each experiment: no processed meal (control); meal thermally treated in an autoclave with xylose (autoclave); meal thermally treated in a conventional oven with xylose (oven); meal thermally treated in a microwave with xylose (microwave); and meal treated with tannin (tannin). All diets contained 60% concentrate (corn, minerals, and processed meal). Fermenters were fed 55 g of dry matter per day, divided equally into two meals at 06:00 and 18:00 h. The solid and liquid dilution rates were adjusted daily to 5.5% and 11% per hour, respectively. On days 8, 9, and 10, 500 mL samples of solid and liquid digesta effluent were collected, mixed, homogenized, and stored at −20 °C. Subsamples of 10 mL were preserved with 0.2 mL of a 50% H2SO4 solution for later determination of NH3-N and volatile fatty acids. Microbial biomass was isolated from the fermenters for chemical analysis at the end of each experimental period. Data were analyzed using the MIXED procedure in SAS with a significance level of α = 0.05. Regarding cottonseed meal, the tannin treatment tended to have a lower true digestibility of DM compared to the control, autoclave, and oven treatments (p = 0.09). Additionally, tannin fermenters exhibited a lower apparent digestibility of CP compared to all other treatments (p = 0.04). The tannin and microwave treatments resulted in the highest flow of dietary nitrogen and the lowest supply of RDP-N (p < 0.01). The control treatment had a greater flow of NH3-N compared to other treatments (p < 0.01). Regarding peanut meal, the autoclave and tannin treatments exhibited the highest acetate concentration (p = 0.03) and the lowest apparent digestibility of CP (p < 0.01). The tannin treatment increased the RUP content without impairing ruminal fermentation and exhibited a greater supply of RDP-N compared to all other treatments (p = 0.02). No significant differences were observed for the other digestibility and fermentation parameters (p > 0.20). Our results indicate that tannin inclusion and microwave processing were the most effective methods for reducing the protein fraction available in the rumen for cottonseed meal. Additionally, tannin inclusion increased the RUP in peanut meal without negatively affecting ruminal fermentation. Full article
(This article belongs to the Special Issue Ruminal Fermentation)
18 pages, 1059 KiB  
Article
The Effect of Alpine Herbs on the Microbiota of In Vitro Rumen Fermentation
by Jonas Andersen, Selene Massaro, Giulia Dallavalle, Pavel Solovyev, Luana Bontempo, Franco Tagliapietra and Elena Franciosi
Fermentation 2025, 11(2), 83; https://doi.org/10.3390/fermentation11020083 - 7 Feb 2025
Viewed by 996
Abstract
Milk from cows grazing on alpine pastures has higher quality than milk from indoor-fed cows, likely due to diet-driven differences in rumen microbiota. We assessed the effects of supplementing alpine herbs—each varying in its content of fiber, protein, and polyphenol—on rumen microbiota via [...] Read more.
Milk from cows grazing on alpine pastures has higher quality than milk from indoor-fed cows, likely due to diet-driven differences in rumen microbiota. We assessed the effects of supplementing alpine herbs—each varying in its content of fiber, protein, and polyphenol—on rumen microbiota via in vitro fermentation, comparing these to a grass hay control using metagenomic sequencing. Fermentations with alpine herbs compared to grass hay control had higher content of fibrolytic Prevotella and lower abundances of Butyrivibrio, Ruminococcaceae, Anaerovibrio, Succiniclasticum, and Desulfovibrio. Fermentations with high starch content (Alchemilla vulgaris, Gallium odoratum and Sanguisorba officinalis) had low, microbial diversity, while fermentations with high content of structural fibre (Sisymbrium officinale, Tanacetum vulgare, and Cicerbita alpina) had high microbial diversity. C. alpina, Sa. officinalis, and T. vulgare fermentations that had high lignin content showed a higher abundance of Bacteroidetes and a lower abundance of Firmicutes. Fermentations with high protein content (G. odoratum and T. vulgare) induced higher abundance of fibrolytic Lachnospiraceae. Sa. officinalis and A. vulgaris fermentations with high content of polyphenols were associated with increased abundances of Streptococcus and family RF-16 and lower abundances of family BS11 and Desulfovibrio. Fermentations with C. alpina and Si. Officinale induced higher abundance of fibrolytic Fibrobacter succinogenes. The beta diversity between fermentations corresponded to differences in the contents of protein, lignin, and polyphenols in the plant material. In conclusion, different herbs can promote the abundance of various fibrinolytic bacteria and change the microbial diversity, which has potential to increase the feed efficiency and the robustness of microbiota and reduce methane production. Full article
(This article belongs to the Special Issue Ruminal Fermentation)
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15 pages, 3421 KiB  
Article
Effects of Artemisia argyi Aqueous Extract on Rumen Fermentation Parameters and Microbiota in Lambs
by Ruiheng Gao, Juan Du, Gen Gang, Xiao Jin, Yuanyuan Xing, Yuanqing Xu, Lei Hong, Sumei Yan and Binlin Shi
Fermentation 2025, 11(2), 53; https://doi.org/10.3390/fermentation11020053 - 24 Jan 2025
Viewed by 927
Abstract
This study sought to evaluate the effects of Artemisia argyi aqueous extract (AAE) on rumen fermentation parameters and the microbiota within the rumen of lambs. A total of 32 lambs that are 3 months old and 24.06 ± 0.04 kg in body weight [...] Read more.
This study sought to evaluate the effects of Artemisia argyi aqueous extract (AAE) on rumen fermentation parameters and the microbiota within the rumen of lambs. A total of 32 lambs that are 3 months old and 24.06 ± 0.04 kg in body weight were randomly assigned to four treatment groups, with eight replicates per treatment. The diets for the four groups were formulated with the following adding dose of AAE: 0 mg/kg (CON), 500 mg/kg (AAE-L), 1000 mg/kg (AAE-M), and 1500 mg/kg (AAE-H), respectively. The results showed that, compared to the CON group, three AAE add groups significantly decreased the A/P ratio; AAE-M and AAE-H groups significantly increased MCP and propionic acid contents. Supplementation with AAE had no significant effect on the alpha and beta diversity of the rumen microbiota, but significantly increased the relative abundances of beneficial bacteria, such as Actinobacteriota in the rumen. In conclusion, AAE supplementation improved the rumen fermentation and microbiota of lambs. In the overall consideration, under the conditions of this research, the supplementation of 1000 mg/kg AAE was optimal. Full article
(This article belongs to the Special Issue Ruminal Fermentation)
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16 pages, 923 KiB  
Article
Preliminary Study on the Impact of Ruminal Ciliate Inoculation in Fauna-Free Conditions on the Ruminal Fermentation and Ciliate–Prokaryote Association In Vitro
by Geonwoo Kim, Woohyung Lee and Tansol Park
Fermentation 2025, 11(1), 28; https://doi.org/10.3390/fermentation11010028 - 11 Jan 2025
Viewed by 726
Abstract
Ruminants rely on the rumen for the anaerobic fermentation of fibrous plant materials, facilitated by a complex microbial community of bacteria, archaea, fungi, and ciliates. Among them, ruminal ciliates significantly influence ruminal fermentation, methane production, nitrogen utilization efficiency, and microbial interactions. This study [...] Read more.
Ruminants rely on the rumen for the anaerobic fermentation of fibrous plant materials, facilitated by a complex microbial community of bacteria, archaea, fungi, and ciliates. Among them, ruminal ciliates significantly influence ruminal fermentation, methane production, nitrogen utilization efficiency, and microbial interactions. This study examined the impact of ciliate inoculation on ruminal fermentation, microbial composition, and functional profiles in fauna-free conditions. Six treatments were tested: control (no ciliates), small entodinia, Epidinium spp., isotrichids, Ophryoscolex spp., and a mixed inoculum. Using QIIME2 to analyze 16S rRNA gene sequences, the study revealed group-specific effects on methane production, volatile fatty acids (VFAs), and microbial diversity. Small entodinia inoculation increased Streptococcus abundance, while isotrichids enriched Megasphaera, enhancing butyrate production. Alpha diversity indices indicated reduced richness in the ciliate-inoculated groups, reflecting predation on prokaryotes. Beta diversity showed distinct microbial and functional profiles among the treatments. Functional analysis highlighted elevated glycerolipid metabolism in isotrichid groups, associated with Bacteroides and Megasphaera, suggesting roles in lipid metabolism and oxidative stress resistance. Despite limited ciliate cell counts, the study emphasizes ciliate-specific interactions and the role of lactic acid-associated bacteria in shaping ruminal fermentation. Full article
(This article belongs to the Special Issue Ruminal Fermentation)
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12 pages, 630 KiB  
Article
Ferulic Acid and Clinoptilolite Affect In Vitro Rumen Fermentation Characteristics and Bacterial Abundance
by Ana Tánori-Lozano, M. Ángeles López-Baca, Adriana Muhlia-Almazán, Maricela Montalvo-Corral, Araceli Pinelli-Saavedra, Thalia Y. Islava-Lagarda, José Luis Dávila-Ramírez, Martín Valenzuela-Melendres and Humberto González-Rios
Fermentation 2024, 10(11), 549; https://doi.org/10.3390/fermentation10110549 - 26 Oct 2024
Cited by 1 | Viewed by 1182
Abstract
This study evaluated the effects of clinoptilolite (CTL) and ferulic acid (FA) supplementation on in vitro ruminal fermentation characteristics, gas production, and bacterial abundance. Treatments were arranged in a 2 × 2 factorial design (FA: 0 or 300 ppm; CTL: 0 or 1%) [...] Read more.
This study evaluated the effects of clinoptilolite (CTL) and ferulic acid (FA) supplementation on in vitro ruminal fermentation characteristics, gas production, and bacterial abundance. Treatments were arranged in a 2 × 2 factorial design (FA: 0 or 300 ppm; CTL: 0 or 1%) with repeated measures over time (2, 4, 8, 12, 24, 36, 48, and 72 h). Throughout the incubation period, the CTL and FAZ treatments recorded the highest pH values (p ≤ 0.05), maintaining levels closest to neutrality after 72 h. After 48 and 72 h, FA and CTL decreased (p ≤ 0.05) the ammonia concentrations while increasing (p ≤ 0.05) acetate and propionate. The methane, butyrate, and iso-VFA concentrations were unaffected (p > 0.05) by any treatment. FA increased the total gas production throughout the experimental period (p ≤ 0.05). Additionally, FA and CTL significantly reduced the relative abundance of Ruminococcus albus and Streptococcus bovis (p ≤ 0.05), while no significant effects were observed for Selenomonas ruminantium (p > 0.05). These findings suggest that both additives can positively modify the rumen fermentation characteristics and microbial composition, which could significantly contribute to animal nutrition by providing a promising strategy for enhancing rumen fermentation. Full article
(This article belongs to the Special Issue Ruminal Fermentation)
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Review

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16 pages, 313 KiB  
Review
Ferulic Acid Esterase-Producing Lactobacilli as Silage Inoculants: A Review on the Efficacy of Improving Fiber Composition and Digestibility of Forages
by Estefanía Andrada, María Claudia Abeijón-Mukdsi, Gabriel Vinderola and Roxana Beatriz Medina
Fermentation 2024, 10(12), 614; https://doi.org/10.3390/fermentation10120614 - 30 Nov 2024
Cited by 1 | Viewed by 988
Abstract
Environmental-, animal-, and plant-associated factors are involved in the intake and digestibility of forages. Ferulated crosslinks are key targets for increasing the extent of fiber digestion in forages, for which ferulic acid esterase-producing lactic acid bacteria (FAE+ LAB) arise as silage inoculants that [...] Read more.
Environmental-, animal-, and plant-associated factors are involved in the intake and digestibility of forages. Ferulated crosslinks are key targets for increasing the extent of fiber digestion in forages, for which ferulic acid esterase-producing lactic acid bacteria (FAE+ LAB) arise as silage inoculants that could beneficially impact animal husbandry. In this review article, we analyze the published effects of these inoculants on silage fiber composition, digestibility measures, ferulic acid content, and animal performance. To date, 17 FAE+ LAB strains have been evaluated in ensiling trials, obtaining variable results. When significant effects were detected, reductions in the content of neutral or acid detergent fiber (1.3–6.6% DM, compared with uninoculated silages) and increased digestibility measures (1.4–9.6% DM) were the most frequent outcomes. FAE+ LAB increased the free FA content of silages in several reports. Factors involved in the variability of responses have been scarcely evaluated but include inoculant strain, strain–forage combination, forage characteristics, and ensiling conditions. Two studies indicate that productive and health improvements were obtained when FAE+ LAB-inoculated silages were predominant in the diet of growing steers or dairy goats. Additional research is needed to understand the factors associated with the performance of FAE+ inoculants and the extent of their potential benefits for animal nutrition. Full article
(This article belongs to the Special Issue Ruminal Fermentation)

Other

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16 pages, 2790 KiB  
Systematic Review
The Use of Mesquite Pods (Prosopis spp.) as an Alternative to Improve the Productive Performance and Methane Mitigation in Small Ruminants: A Meta-Analysis
by Juan Carlos Angeles-Hernandez, Ever del Jesús Flores Santiago, Eduardo Cardoso-Gutiérrez, Sara S. Valencia-Salazar, Oscar Enrique del Razo Rodriguez, Erwin A. Paz, Juan C. Ku-Vera, Ermias Kebreab, Mohammed Benaouda and Ángel Garduño García
Fermentation 2024, 10(12), 625; https://doi.org/10.3390/fermentation10120625 - 7 Dec 2024
Cited by 1 | Viewed by 1183
Abstract
Mesquite (Prosopis spp.), a highly nutritious legume from arid regions characterized by its secondary metabolites, offers a cost-effective resource to provide energy and protein for small ruminant farmers in harsh environments. In addition, the high concentrations of secondary metabolites found in mesquite [...] Read more.
Mesquite (Prosopis spp.), a highly nutritious legume from arid regions characterized by its secondary metabolites, offers a cost-effective resource to provide energy and protein for small ruminant farmers in harsh environments. In addition, the high concentrations of secondary metabolites found in mesquite pods could be an option to mitigate methane (CH4) emissions. Thus, the aim of this study was to conduct an analytical review to assess the impact of adding mesquite pods on small ruminant productivity and enteric CH4 emissions. A comprehensive and structured search of scientific articles resulted in a database of 38 trials. The response variables were evaluated through raw mean differences (RMDs) and standardized mean differences (SMDs), followed by a meta-regression, used to investigate the heterogeneity of the explanatory variables. Supplementation with mesquite pods significantly increased the dry matter intake (DMI) and average daily gain (ADG) and reduced the feed conversion ratio (FCR), with sheep showing the highest effect. The meta-regression demonstrated that the mesquite pod effect was influenced mainly by the species, level of incorporation and processing of the pods. Studies employing in silico CH4 estimation reported increased emissions when the diets included mesquite pods. In contrast, in vivo studies demonstrated promising results, showing a significant reduction in CH4 emissions when mesquite pods were included in small ruminant diets. Therefore, future research should focus on evaluating mesquite pod supplementation using precise methods to assess CH4 emissions. Full article
(This article belongs to the Special Issue Ruminal Fermentation)
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7 pages, 223 KiB  
Opinion
Impacts of Slow-Release Urea in Ruminant Diets: A Review
by Szu-Wei Ma and Antonio P. Faciola
Fermentation 2024, 10(10), 527; https://doi.org/10.3390/fermentation10100527 - 17 Oct 2024
Cited by 4 | Viewed by 2974
Abstract
The increasing costs of traditional protein sources, such as soybean meal (SBM), have prompted interest in alternative feeds for ruminants. Non-protein nitrogen (NPN) sources, like urea, offer a cost-effective alternative by enabling rumen microorganisms to convert NPN into microbial protein, which is crucial [...] Read more.
The increasing costs of traditional protein sources, such as soybean meal (SBM), have prompted interest in alternative feeds for ruminants. Non-protein nitrogen (NPN) sources, like urea, offer a cost-effective alternative by enabling rumen microorganisms to convert NPN into microbial protein, which is crucial for ruminant nutrition. However, the rapid hydrolysis of urea in the rumen can result in excessive ammonia (NH3) production and potential toxicity. Slow-release urea (SRU) has been developed to mitigate these issues by gradually releasing nitrogen, thereby improving nutrient utilization and reducing NH3 toxicity risks. This review explores SRU’s development, types, mechanisms, and benefits, highlighting its potential to enhance ruminal fermentation, microbial protein synthesis, and overall feed efficiency. SRU formulations include polymer-coated urea, lipid-coated urea, calcium-urea, starea, and zeolite-impregnated urea, each designed to control nitrogen release and minimize adverse effects. Studies have demonstrated that SRU can improve microbial nitrogen efficiency and reduce nitrogen losses, although results regarding feed intake, digestibility, and milk yield are mixed. These discrepancies indicate that factors such as SRU type, diet formulation, and animal breed may influence outcomes. Continued research is essential to optimize SRU applications, aiming to enhance ruminant production, economic viability, and environmental stewardship. Full article
(This article belongs to the Special Issue Ruminal Fermentation)
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