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Mohammadi M, Alian M, Dale B, Ubanwa B, Balan V. Multifaced application of AFEX-pretreated biomass in producing second-generation biofuels, ruminant animal feed, and value-added bioproducts. Biotechnol Adv 2024; 72:108341. [PMID: 38499256 DOI: 10.1016/j.biotechadv.2024.108341] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2024] [Revised: 03/06/2024] [Accepted: 03/15/2024] [Indexed: 03/20/2024]
Abstract
Lignocellulosic biomass holds a crucial position in the prospective bio-based economy, serving as a sustainable and renewable source for a variety of bio-based products. These products play a vital role in displacing fossil fuels and contributing to environmental well-being. However, the inherent recalcitrance of biomass poses a significant obstacle to the efficient access of sugar polymers. Consequently, the bioconversion of lignocellulosic biomass into fermentable sugars remains a prominent challenge in biorefinery processes to produce biofuels and biochemicals. In addressing these challenges, extensive efforts have been dedicated to mitigating biomass recalcitrance through diverse pretreatment methods. One noteworthy process is Ammonia Fiber Expansion (AFEX) pretreatment, characterized by its dry-to-dry nature and minimal water usage. The volatile ammonia, acting as a catalyst in the process, is recyclable. AFEX contributes to cleaning biomass ester linkages and facilitating the opening of cell wall structures, enhancing enzyme accessibility and leading to a fivefold increase in sugar conversion compared to untreated biomass. Over the last decade, AFEX has demonstrated substantial success in augmenting the efficiency of biomass conversion processes. This success has unlocked the potential for sustainable and economically viable biorefineries. This paper offers a comprehensive review of studies focusing on the utilization of AFEX-pretreated biomass in the production of second-generation biofuels, ruminant feed, and additional value-added bioproducts like enzymes, lipids, proteins, and mushrooms. It delves into the details of the AFEX pretreatment process at both laboratory and pilot scales, elucidates the mechanism of action, and underscores the role of AFEX in the biorefinery for developing biofuels and bioproducts, and nutritious ruminant animal feed production. While highlighting the strides made, the paper also addresses current challenges in the commercialization of AFEX pretreatment within biorefineries. Furthermore, it outlines critical considerations that must be addressed to overcome these challenges, ensuring the continued progress and widespread adoption of AFEX in advancing sustainable and economically viable bio-based industries.
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Affiliation(s)
- Maedeh Mohammadi
- Department of Engineering Technology, Cullen College of Engineering, University of Houston, Sugarland, TX 77479, USA
| | - Mahsa Alian
- Department of Engineering Technology, Cullen College of Engineering, University of Houston, Sugarland, TX 77479, USA
| | - Bruce Dale
- Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing, MI 48824, USA
| | - Bryan Ubanwa
- Department of Engineering Technology, Cullen College of Engineering, University of Houston, Sugarland, TX 77479, USA
| | - Venkatesh Balan
- Department of Engineering Technology, Cullen College of Engineering, University of Houston, Sugarland, TX 77479, USA.
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Bontà V, Battelli M, Rama E, Casanova M, Pasotti L, Galassi G, Colombini S, Calvio C. An In Vitro Study on the Role of Cellulases and Xylanases of Bacillus subtilis in Dairy Cattle Nutrition. Microorganisms 2024; 12:300. [PMID: 38399704 PMCID: PMC10891753 DOI: 10.3390/microorganisms12020300] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2024] [Revised: 01/26/2024] [Accepted: 01/29/2024] [Indexed: 02/25/2024] Open
Abstract
The administration of Bacilli to dairy cows exerts beneficial effects on dry matter intake, lactation performance, and milk composition, but the rationale behind their efficacy is still poorly understood. In this work, we sought to establish whether cellulases and xylanases, among the enzymes secreted by B. subtilis, are involved in the positive effect exerted by Bacilli on ruminal performance. We took advantage of two isogenic B. subtilis strains, only differing in the secretion levels of those two enzymes. A multi-factorial study was conducted in which eight feed ingredients were treated in vitro, using ruminal fluid from cannulated cows, with cultures of the two strains conveniently grown in a growth medium based on inexpensive waste. Feed degradability and gas production were assessed. Fiber degradability was 10% higher (p < 0.001) in feeds treated with the enzyme-overexpressing strain than in the untreated control, while the non-overexpressing strain provided a 5% increase. The benefit of the fibrolytic enzymes was maximal for maize silage, the most recalcitrant feed. Gas production also correlated with the amount of enzymes applied (p < 0.05). Our results revealed that B. subtilis cellulases and xylanases effectively contribute to improving forage quality, justifying the use of Bacilli as direct-fed microbials to increase animal productivity.
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Affiliation(s)
- Valeria Bontà
- Laboratories of Genetics and Microbiology, Department of Biology and Biotechnology, University of Pavia, Via Ferrata 9, 27100 Pavia, Italy
| | - Marco Battelli
- Department of Agricultural and Environmental Sciences, University of Milan, Via Celoria 2, 20133 Milan, Italy; (M.B.); (G.G.); (S.C.)
| | - Erlinda Rama
- Laboratories of Genetics and Microbiology, Department of Biology and Biotechnology, University of Pavia, Via Ferrata 9, 27100 Pavia, Italy
| | - Michela Casanova
- Department of Electrical, Computer and Biomedical Engineering, University of Pavia, Via Ferrata 5, 27100 Pavia, Italy (L.P.)
| | - Lorenzo Pasotti
- Department of Electrical, Computer and Biomedical Engineering, University of Pavia, Via Ferrata 5, 27100 Pavia, Italy (L.P.)
| | - Gianluca Galassi
- Department of Agricultural and Environmental Sciences, University of Milan, Via Celoria 2, 20133 Milan, Italy; (M.B.); (G.G.); (S.C.)
| | - Stefania Colombini
- Department of Agricultural and Environmental Sciences, University of Milan, Via Celoria 2, 20133 Milan, Italy; (M.B.); (G.G.); (S.C.)
| | - Cinzia Calvio
- Laboratories of Genetics and Microbiology, Department of Biology and Biotechnology, University of Pavia, Via Ferrata 9, 27100 Pavia, Italy
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Dong H, Sousa LDC, Ubanwa B, Jones AD, Balan V. A New Method to Overcome Carboxyamide Formation During AFEX Pretreatment of Lignocellulosic Biomass. Front Chem 2022; 9:826625. [PMID: 35127657 PMCID: PMC8814328 DOI: 10.3389/fchem.2021.826625] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Accepted: 12/28/2021] [Indexed: 12/30/2022] Open
Abstract
Lignin-carbohydrate complexes (LCCs) in the plant cell wall are responsible for providing resistance against biomass-degrading enzymes produced by microorganisms. Four major types of lignin-carbohydrate bonds are reported in the literature, namely, benzyl ethers, benzyl esters, phenyl glycosides, and acetyl ester linkages. Ester’s linkages in the plant cell wall are labile to alkaline pretreatments, such as ammonia fiber expansion (AFEX), which uses liquid or gaseous ammonia to cleave those linkages in the plant cell wall and reduce biomass recalcitrance. Two competing reactions, notably hydrolysis and ammonolysis, take place during AFEX pretreatment process, producing different aliphatic and aromatic acids, as well as their amide counterparts. AFEX pretreated grasses and agricultural residues are known to increase conversion of biomass to sugars by four- to five-fold when subjected to commercial enzyme hydrolysis, yielding a sustainable feedstock for producing biofuels, biomaterials, and animal feed. Animal feed trials on dairy cows have demonstrated a 27% increase in milk production when compared to a control feedstock. However, the presence of carboxamides in feedstocks could promote neurotoxicity in animals if consumed beyond a certain concentration. Thus, there is the need to overcome regulatory hurdles associated with commercializing AFEX pretreated biomass as animal feed in the United States. This manuscript demonstrates a modified pretreatment for increasing the digestibility of industrial byproducts such as Brewer’s spent grains (BSG) and high-fiber meal (HFM) produced from BSG and dry distillers grains with soluble (DDGS), while avoiding the production of carboxamides. The three industrial byproducts were first treated with calculated amounts of alkali such as NaOH, Ca(OH)2, or KOH followed by AFEX pretreatment. We found that 4% alkali was able to de-esterify BSG and DDGS more efficiently than using 2% alkali at both 10 and 20% solids loading. AFEX pretreatment of de-esterified BSG, HFM, and DDGS produced twofold higher glucan conversion than respective untreated biomass. This new discovery can help overcome potential regulatory issues associated with the presence of carboxamides in ammonia-pretreated animal feeds and is expected to benefit several farmers around the world.
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Affiliation(s)
- Hui Dong
- Department of Chemical Engineering and Material Science, Michigan State University, Lansing, MI, United States
| | - Leonardo da Costa Sousa
- Department of Chemical Engineering and Material Science, Michigan State University, Lansing, MI, United States
| | - Bryan Ubanwa
- Department of Engineering Technology, College of Technology, University of Houston, Sugarland, TX, United States
| | - A. Daniel Jones
- Great Lakes Bioenergy Center, Michigan State University, East Lansing, MI, United States
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, United States
| | - Venkatesh Balan
- Department of Chemical Engineering and Material Science, Michigan State University, Lansing, MI, United States
- Department of Engineering Technology, College of Technology, University of Houston, Sugarland, TX, United States
- *Correspondence: Venkatesh Balan,
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Terry SA, Basarab JA, Guan LL, McAllister TA. Strategies to improve the efficiency of beef cattle production. CANADIAN JOURNAL OF ANIMAL SCIENCE 2021. [DOI: 10.1139/cjas-2020-0022] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Globally, there are approximately one billion beef cattle, and compared with poultry and swine, beef cattle have the poorest conversion efficiency of feed to meat. However, these metrics fail to consider that beef cattle produce high-quality protein from feeds that are unsuitable for other livestock species. Strategies to improve the efficiency of beef cattle are focusing on operational and breeding management, host genetics, functional efficiency of rumen and respiratory microbiomes, and the structure and composition of feed. These strategies must also consider the health and immunity of the herd as well as the need for beef cattle to thrive in a changing environment. Genotyping can identify hybrid vigor with positive consequences for animal health, productivity, and environmental adaptability. The role of microbiome–host interactions is key in efficient nutrient digestion and host health. Microbial markers and gene expression patterns within the rumen microbiome are being used to identify hosts that are efficient at fibre digestion. Plant breeding and processing are optimizing the feed value of both forages and concentrates. Strategies to improve the efficiency of cattle production are a prerequisite for the sustainable intensification needed to satisfy the future demand for beef.
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Affiliation(s)
- Stephanie A. Terry
- Agriculture and Agri-Food Canada, Lethbridge Research and Development Centre, 5403 1st Avenue South, Lethbridge, AB T1J 4B1, Canada
| | - John A. Basarab
- Alberta Agriculture and Forestry, Lacombe Research and Development Centre, 6000 C&E Trail, Lacombe, AB T4L 1W1, Canada
| | - Le Luo Guan
- Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB T6G 2P5, Canada
| | - Tim A. McAllister
- Agriculture and Agri-Food Canada, Lethbridge Research and Development Centre, 5403 1st Avenue South, Lethbridge, AB T1J 4B1, Canada
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Ribeiro GO, Gruninger RJ, Jones DR, Beauchemin KA, Yang WZ, Wang Y, Abbott DW, Tsang A, McAllister TA. Effect of ammonia fiber expansion-treated wheat straw and a recombinant fibrolytic enzyme on rumen microbiota and fermentation parameters, total tract digestibility, and performance of lambs. J Anim Sci 2020; 98:skaa116. [PMID: 32369600 PMCID: PMC7199887 DOI: 10.1093/jas/skaa116] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2019] [Accepted: 04/28/2020] [Indexed: 12/30/2022] Open
Abstract
The objective of this study was to evaluate the effect of ammonia fiber expansion (AFEX)-treated wheat straw pellets and a recombinant fibrolytic enzyme on the rumen microbiome, rumen fermentation parameters, total tract diet digestibility, and performance of lambs. Eight rumen cannulated wethers and 60 lambs (n = 15 per diet, 8 rams and 7 ewes) were used in a replicated 4 × 4 Latin square design digestibility study and a complete randomized growth performance study, respectively. Four treatment diets were arranged in a 2 × 2 factorial structure with AFEX wheat straw (0% or 30% AFEX straw pellets on a dietary DM basis replacing alfalfa hay pellets) and fibrolytic enzyme (with or without XYL10C, a β-1,4-xylanase, from Aspergillus niger) as main factors. Enzyme was applied at 100 mg/kg of diet DM, 22 h before feeding. Rumen bacteria diversity Pielou evenness decreased (P = 0.05) with AFEX compared with the control diet and increased (P < 0.01) with enzyme. Enzyme increased (P ≤ 0.02) the relative abundancies of Prevotellaceae UCG-004, Christensenellaceae R-7 group, Saccharofermentans, and uncultured Kiritimatiellaeota. Total protozoa counts were greater (P ≤ 0.04) in the rumen of lambs fed AFEX compared with control, with enzyme reducing (P ≤ 0.05) protozoa counts for both diets. Digestibility of DM did not differ (P > 0.10) among diets, but digestibility of CP was reduced (P = 0.001), and digestibility of NDF and ADF increased (P < 0.05) as AFEX replaced alfalfa. Compared with control, AFEX promoted greater DMI (P = 0.003) and improved ADG up to 42 d on feed (P = 0.03), but not (P = 0.51) over the full ~94-d experiment. Consequently, overall G:F was reduced (P = 0.04) for AFEX when compared with control (0.188 vs. 0.199), but days on feed were lower (P = 0.04) for AFEX (97 vs. 91 d). Enzyme improved DMI of AFEX up to day 70 (P = 0.01), but did not affect DMI of the control diet. Enzyme addition improved ADG of lambs fed both diets in the first 28 d (P = 0.02), but not over the entire feeding period (P ≥ 10). As a result, G:F was improved with enzyme for the first 28 d (P = 0.04), but not overall (P = 0.45). This study shows that AFEX-treated wheat straw can replace alfalfa hay with no loss in lamb growth performance. Additionally, the enzyme XYL10C altered the rumen microbiome and improved G:F in the first month of the feeding.
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Affiliation(s)
- Gabriel O Ribeiro
- Department of Animal and Poultry Science, University of Saskatchewan College of Agriculture Bioresources, University of Saskatchewan, Saskatoon, Canada
| | - Robert J Gruninger
- Lethbridge Research and Development Centre, Agriculture and Agri-Food Canada, Lethbridge, Canada
| | - Darryl R Jones
- Lethbridge Research and Development Centre, Agriculture and Agri-Food Canada, Lethbridge, Canada
| | - Karen A Beauchemin
- Lethbridge Research and Development Centre, Agriculture and Agri-Food Canada, Lethbridge, Canada
| | - Wen Zhu Yang
- Lethbridge Research and Development Centre, Agriculture and Agri-Food Canada, Lethbridge, Canada
| | - Yuxi Wang
- Lethbridge Research and Development Centre, Agriculture and Agri-Food Canada, Lethbridge, Canada
| | - D Wade Abbott
- Lethbridge Research and Development Centre, Agriculture and Agri-Food Canada, Lethbridge, Canada
| | - Adrian Tsang
- Centre for Structural and Functional Genomics, Concordia University, Montreal, Canada
| | - Tim A McAllister
- Lethbridge Research and Development Centre, Agriculture and Agri-Food Canada, Lethbridge, Canada
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6
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Passetti RA, Passetti LC, Gruninger RJ, Ribeiro GO, Marami Milani MR, Prado IN, McAllister TA. Effect of ammonia fibre expansion (AFEX) treatment of rice straw on in situ digestibility, microbial colonization, acetamide levels and growth performance of lambs. Anim Feed Sci Technol 2020. [DOI: 10.1016/j.anifeedsci.2020.114411] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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7
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Campbell T, Bals B, Teymouri F, Glassbrook J, Nielson C, Videto J, Rinard A, Moore J, Julian A, Bringi V. Scale-up and operation of a pilot-scale ammonia fiber expansion reactor. Biotechnol Bioeng 2019; 117:1241-1246. [PMID: 31840804 DOI: 10.1002/bit.27251] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Revised: 12/12/2019] [Accepted: 12/13/2019] [Indexed: 11/10/2022]
Abstract
Pretreatment and densification of agricultural residues at regional depots can simplify feedstock supply logistics for the production of biofuels in commercial biorefineries. We have previously reported the performance of a laboratory-scale (5 L) packed-bed ammonia fiber expansion (AFEX) reactor system, which showed significant promise for biomass pretreatment at distributed depots. In this paper, we describe the performance of a 90-fold larger pilot-scale packed-bed AFEX-reactor system, used to produce over 1,500 batches (~36 tons) of pretreated crop residues over a 5-year period. Virtually all unreacted ammonia was successfully removed from the biomass, and 76% of the ammonia was recycled and reused. Pretreatment performance at pilot scale was comparable to laboratory-scale, averaging 74% glucose and 75% xylose yield in a standard test compared with 71% and 73%, respectively. Other operating and maintenance aspects are also discussed.
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Affiliation(s)
- Tim Campbell
- Michigan Biotechnology Institute, Lansing, Michigan
| | - Bryan Bals
- Michigan Biotechnology Institute, Lansing, Michigan
| | | | | | | | - Josh Videto
- Michigan Biotechnology Institute, Lansing, Michigan
| | | | | | - Allen Julian
- Michigan Biotechnology Institute, Lansing, Michigan
| | - Venkataraman Bringi
- Department of Chemical Engineering and Material Science, Michigan State University, East Lansing, Michigan
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Bals B, Teymouri F, Haddad D, Julian WA, Vismeh R, Jones AD, Mor P, Van Soest B, Tyagi A, VandeHaar M, Bringi V. Presence of Acetamide in Milk and Beef from Cattle Consuming AFEX-Treated Crop Residues. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2019; 67:10756-10763. [PMID: 31483626 PMCID: PMC6764021 DOI: 10.1021/acs.jafc.9b04030] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
AFEX treatment of crop residues can greatly increase their nutrient availability for ruminants. This study investigated the concentration of acetamide, an ammoniation byproduct, in AFEX-treated crop residues and in milk and meat from ruminants fed these residues. Acetamide concentrations in four AFEX-treated cereal crop residues were comparable and reproducible (4-7 mg/g dry matter). A transient acetamide peak in milk was detected following introduction of AFEX-treated residues to the diet, but an alternative regimen showed the peak can be effectively mitigated. Milk acetamide concentration following this transition was 6 and 10 ppm for cattle and buffalo, respectively, but also decreased over time for cattle while tending to decrease (p = 0.08) for buffalo. There was no difference in acetamide concentration in the meat of cattle consuming AFEX-treated residues for 160 days compared to controls. Further investigation is necessary to determine the metabolism of acetamide in ruminants and a maximum acceptable daily intake for humans.
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Affiliation(s)
- Bryan Bals
- Michigan
Biotechnology Institute, Lansing Michigan 48910, United States
- E-mail:
| | - Farzaneh Teymouri
- Michigan
Biotechnology Institute, Lansing Michigan 48910, United States
| | - Diane Haddad
- Michigan
Biotechnology Institute, Lansing Michigan 48910, United States
| | - W. Allen Julian
- Michigan
Biotechnology Institute, Lansing Michigan 48910, United States
| | - Ramin Vismeh
- Michigan
Biotechnology Institute, Lansing Michigan 48910, United States
| | - A. Daniel Jones
- Department of Biochemistry
and Molecular Biology, Deptartment of Animal Science, and Department of
Chemical Engineering and Material Science, Michigan State University, East Lansing Michigan 48823, United States
| | - Preeti Mor
- Dairy
Cattle Nutrition Division, National Dairy
Research Institute, Karnal, Haryana 132001, India
| | - Brandon Van Soest
- Department of Biochemistry
and Molecular Biology, Deptartment of Animal Science, and Department of
Chemical Engineering and Material Science, Michigan State University, East Lansing Michigan 48823, United States
| | - Amrish Tyagi
- Dairy
Cattle Nutrition Division, National Dairy
Research Institute, Karnal, Haryana 132001, India
| | - Michael VandeHaar
- Department of Biochemistry
and Molecular Biology, Deptartment of Animal Science, and Department of
Chemical Engineering and Material Science, Michigan State University, East Lansing Michigan 48823, United States
| | - Venkataraman Bringi
- Department of Biochemistry
and Molecular Biology, Deptartment of Animal Science, and Department of
Chemical Engineering and Material Science, Michigan State University, East Lansing Michigan 48823, United States
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Beauchemin KA, Ribeiro GO, Ran T, Marami Milani MR, Yang W, Khanaki H, Gruninger R, Tsang A, McAllister TA. Recombinant fibrolytic feed enzymes and ammonia fibre expansion (AFEX) pretreatment of crop residues to improve fibre degradability in cattle. Anim Feed Sci Technol 2019. [DOI: 10.1016/j.anifeedsci.2019.114260] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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10
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Adesogan AT, Arriola KG, Jiang Y, Oyebade A, Paula EM, Pech-Cervantes AA, Romero JJ, Ferraretto LF, Vyas D. Symposium review: Technologies for improving fiber utilization. J Dairy Sci 2019; 102:5726-5755. [PMID: 30928262 DOI: 10.3168/jds.2018-15334] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Accepted: 01/14/2019] [Indexed: 12/20/2022]
Abstract
The forage lignocellulosic complex is one of the greatest limitations to utilization of the nutrients and energy in fiber. Consequently, several technologies have been developed to increase forage fiber utilization by dairy cows. Physical or mechanical processing techniques reduce forage particle size and gut fill and thereby increase intake. Such techniques increase the surface area for microbial colonization and may increase fiber utilization. Genetic technologies such as brown midrib mutants (BMR) with less lignin have been among the most repeatable and practical strategies to increase fiber utilization. Newer BMR corn hybrids are better yielding than the early hybrids and recent brachytic dwarf BMR sorghum hybrids avoid lodging problems of early hybrids. Several alkalis have been effective at increasing fiber digestibility. Among these, ammoniation has the added benefit of increasing the nitrogen concentration of the forage. However, few of these have been widely adopted due to the cost and the caustic nature of the chemicals. Urea treatment is more benign but requires sufficient urease and moisture for efficacy. Ammonia-fiber expansion technology uses high temperature, moisture, and pressure to degrade lignocellulose to a greater extent than ammoniation alone, but it occurs in reactors and is therefore not currently usable on farms. Biological technologies for increasing fiber utilization such as application of exogenous fibrolytic enzymes, live yeasts, and yeast culture have had equivocal effects on forage fiber digestion in individual studies, but recent meta-analyses indicate that their overall effects are positive. Nonhydrolytic expansin-like proteins act in synergy with fibrolytic enzymes to increase fiber digestion beyond that achieved by the enzyme alone due to their ability to expand cellulose microfibrils allowing greater enzyme penetration of the cell wall matrix. White-rot fungi are perhaps the biological agents with the greatest potential for lignocellulose deconstruction, but they require aerobic conditions and several strains degrade easily digestible carbohydrates. Less ruminant nutrition research has been conducted on brown rot fungi that deconstruct lignocellulose by generating highly destructive hydroxyl radicals via the Fenton reaction. More research is needed to increase the repeatability, efficacy, cost effectiveness, and on-farm applicability of technologies for increasing fiber utilization.
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Affiliation(s)
- A T Adesogan
- Department of Animal Sciences, Institute of Food and Agricultural Sciences, University of Florida, Gainesville 32611.
| | - K G Arriola
- Department of Animal Sciences, Institute of Food and Agricultural Sciences, University of Florida, Gainesville 32611
| | - Y Jiang
- Department of Animal Sciences, Institute of Food and Agricultural Sciences, University of Florida, Gainesville 32611
| | - A Oyebade
- Department of Animal Sciences, Institute of Food and Agricultural Sciences, University of Florida, Gainesville 32611
| | - E M Paula
- Department of Animal Sciences, Institute of Food and Agricultural Sciences, University of Florida, Gainesville 32611
| | - A A Pech-Cervantes
- Department of Animal Sciences, Institute of Food and Agricultural Sciences, University of Florida, Gainesville 32611
| | - J J Romero
- Animal and Veterinary Sciences Program, School of Food and Agriculture, University of Maine, Orono 04469
| | - L F Ferraretto
- Department of Animal Sciences, Institute of Food and Agricultural Sciences, University of Florida, Gainesville 32611
| | - D Vyas
- Department of Animal Sciences, Institute of Food and Agricultural Sciences, University of Florida, Gainesville 32611
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