Submitted Successfully!
To reward your contribution, here is a gift for you: A free trial for our video production service.
Thank you for your contribution! You can also upload a video entry or images related to this topic.
Version Summary Created by Modification Content Size Created at Operation
1 -- 3193 2023-11-29 23:57:36 |
2 layout Meta information modification 3193 2023-11-30 02:15:41 |

Video Upload Options

Do you have a full video?

Confirm

Are you sure to Delete?
Cite
If you have any further questions, please contact Encyclopedia Editorial Office.
Bhandari, K.B.; Rusch, H.L.; Heuschele, D.J. Alfalfa Stem Cell Wall Digestibility. Encyclopedia. Available online: https://encyclopedia.pub/entry/52212 (accessed on 11 October 2024).
Bhandari KB, Rusch HL, Heuschele DJ. Alfalfa Stem Cell Wall Digestibility. Encyclopedia. Available at: https://encyclopedia.pub/entry/52212. Accessed October 11, 2024.
Bhandari, Krishna B., Hannah L. Rusch, Deborah J. Heuschele. "Alfalfa Stem Cell Wall Digestibility" Encyclopedia, https://encyclopedia.pub/entry/52212 (accessed October 11, 2024).
Bhandari, K.B., Rusch, H.L., & Heuschele, D.J. (2023, November 29). Alfalfa Stem Cell Wall Digestibility. In Encyclopedia. https://encyclopedia.pub/entry/52212
Bhandari, Krishna B., et al. "Alfalfa Stem Cell Wall Digestibility." Encyclopedia. Web. 29 November, 2023.
Alfalfa Stem Cell Wall Digestibility
Edit

Alfalfa (Medicago sativa L.) is considered as the most important forage legume with high biomass yield and nutritional quality for ruminants. The alfalfa leaf cell walls are highly digestible, but stem cell walls of alfalfa are not readily digestible. The cell wall component of alfalfa has a large source of dietary energy, but ruminant animals can digest less than half of this component due to the presence of high lignin content.

alfalfa digestibility forage quality lignification reduced-lignin alfalfa

1. Introduction

Alfalfa (Medicago sativa L.) is the most important perennial forage legume in the temperate regions of the world [1], produced primarily for high-quality hay and silage for cattle [2]. This key forage is grown on more than 30 million hectares in the world [3]. In the United States, alfalfa is the third largest crop in dollar value produced with an estimated value of more than USD 10 billion annually [4]. Besides high-quality diets for cattle, alfalfa provides several environmental benefits such as carbon sequestration and mitigation of nitrogen leaching [5], and improves pasture soil health [6][7]. Alfalfa is the best-adapted perennial cool-season legume for hayfields [8][9] and is one of the most resilient forage legumes that can withstand prolonged drought by undergoing dormancy and resuming growth after receiving adequate amounts of water [10][11][12]. Alfalfa can extract water from deep within the soil profile [10]. Thus, crop water losses from deep percolation and runoff can be abated through planting alfalfa, especially during an extended drought. In higher precipitation regions, replacing perennial warm-season grass pastures by alfalfa can prolong the grazing season by earlier initiation of spring grazing and provide greater rate and total weight of stocker cattle [13].
Alfalfa is generally considered to have the greatest nutritive value among the forage crops, because it contains 15–22% crude protein, essential vitamins and their precursors, and several minerals such as calcium, phosphorus, and magnesium [14]. The alfalfa leaf fraction is relatively rich in protein and the leaf cell walls are highly digestible [15]. These high protein and mineral contents of alfalfa provide nutrients for milk and muscle growth in dairy and beef cattle when complemented with balanced energy diets [16][17]. The productivity of dairy cows can be increased with high-quality alfalfa with high dry matter digestibility [16]. The main limitation to nutritive value in alfalfa is the lignification of cell walls of the stem portion [18][19], which composes 50 to 70% of the total shoot biomass [20].
The fiber (cell wall) fraction of forage provides a potentially large source of dietary energy, but animals often readily digest and utilize less than 50% of this fraction [21]. The fiber concentration in alfalfa increases within stems as plants mature, but the fiber concentration in the leaves remains low and constant [22]. An increase in the dry-weight ratio of high digestibility leaves to low digestibility stems in alfalfa improves nutritive value [23], and an increase in the leaf-to-stem ratio increases forage dry-matter intake [24]. Additionally, alfalfa stem digestibility can be affected by several factors such as harvest time, genotype, year, and location [25]. By increasing the digestibility of alfalfa stems, available energy at later maturity stages may also increase along with the increase in dry matter yield. Alfalfa populations with increased fiber digestibility have been developed [26] indicating the possibility of increased fiber digestibility in alfalfa stems.
Screening germplasm for natural variation in traits that confer improved digestibility is one way of improving cell wall digestibility. Researchers using an NIRS-based screening approach found large genetic diversity among alfalfa cultivars and genotypes for stem cell wall digestibility in which that trait was negatively correlated with total lignin concentration [27]. Conventional breeding efforts have resulted in reduced lignin cultivars [25]. As well as the evaluation of individual gene knockdowns in the lignin biosynthetic pathway, identified alfalfa lines with increased stem fiber digestibility [28] have been commercially available since 2015 as reduced-lignin alfalfa cultivars [29]. Another type of variation that might lead to increased digestibility is through anatomical changes in the stem. Some anatomical changes which would increase stem cell wall digestibility include thickening of secondary cell wall of xylem which would inhibit lignification, reducing lignification of phloem fibers or pith parenchyma, or increasing proportion of nonlignified tissues [30].

2. Fiber Digestibility

Fiber in forage is a major source of dietary energy and affects intake and digestibility of forages, but less than 50% of the fiber is readily digested and utilized by ruminant animals [31]. Neutral detergent fiber (NDF) describes highly digestible cell fiber material. Forages with high NDF concentrations and lignified cell walls limit feed intake [32] because the animal feels “full”. The NDF concentration increases rapidly during a rapid decrease in dry matter digestibility after alfalfa matures beyond the vegetative stage. Acid detergent fiber (ADF), on the other hand, describes cell wall material that either is hard to digest or never digests. Forage legumes have more rapidly digestible cell wall than grasses of similar maturity, but the potential extent of cell wall degradation in legumes is generally low [33]. Legume cell walls contain more pectin but less cellulose and hemicellulose compared to grasses [34] which accounts for the initial rapid digestion in legumes. Grasses have vascular bundles distributed throughout the parenchyma of stem cross-sections, whereas the vascular tissues in legumes form a discrete and continuous ring around the stem which expands through cambial activity [35] that impedes ruminal microbe access for digestion. Histological staining for pectin and lignin indicated that tissues may differ more dramatically in their cell wall composition in legumes than grasses [22][36]. Within grass, leaf tissue makes up the greatest proportion of the plant. These leaves have thin-walled, non-lignified mesophyll tissue [37], and mesophyll tissue is found to be completely degraded by rumen microbes [38]. In Alfalfa, where the proportion of stem tissues is larger than grass, the fiber has higher lignin content and thus lower digestibility (40–50%) compared to high fiber digestibility (60–70%) in grasses [31]. Alfalfa has been reported to contain greater lignin and lesser cell wall concentration than grass when alfalfa and grass had the same digestibility [39].
A previous study [22] divided alfalfa stem components into four major categories in relation to cell wall development: chlorenchyma, cambium, secondary phloem, and primary xylem parenchyma consisting of thin, non-lignified primary walls. The pith parenchyma with thin-walled tissue undergoes little cell wall thickening and lignification after stoppage of stem elongation while the collenchyma, epidermis and primary phloem tissues form thick primary walls without lignin at the end of stem elongation. The primary phloem and secondary xylem undergo thickening of secondary cell wall and are highly lignified, after stem elongation is ceased. Alfalfa stems contain diverse tissue types that include thin, non-lignified walls; minimal wall thickening with lignification; thick walls that do not lignify; and thick cell wall that lignify [22]. Tissues which are non-lignified and pectin-rich, such as collenchyma, are considered as rapidly and completely degradable compared to tissues which are lignified and xylan-rich, such as secondary xylem fiber [40]. The non-lignified wall are completely degradable regardless of the thickness, but lignified tissues have variable degradable pattern based on the lignin distribution in the cell wall [19]. Less than 10% of the cell wall has been found to be degradable in alfalfa with thick primary and secondary wall of xylem fiber [19]. Non-lignified epidermis, collenchyma, chlorenchyma, cambium, and primary xylem parenchyma were found to rapidly and completely degrade within the first 8 h of fermentation [19]. Non-lignified secondary walls of the primary phloem fiber completely degrades in 24 h, while the lignified pith parenchyma and secondary xylem fiber were 9.1 to 65.5% degradable even after 96 h, and the primary and secondary xylem vessels were completely nondegradable [19]. However, in grasses, the thick and lignified sclerenchyma tissue were found to be extensively degradable when fermented for 48 h with rumen microbes [36].
Grass cell walls are more degradable than legume cell walls during 72 h to 96 h fermentation [33][41]. Cell wall degradability may be negatively affected by the cross-linkage of matrix components far greater than lignin concentration alone [42]. Although non-lignified alfalfa stems degrade two to five times faster than nonlignified mesophyll grass tissues, lignified alfalfa stem tissues degrade less when compared to reported lignified grass stem sclerenchyma [19]. The differences of cell wall degradation between alfalfa and grass tissues could be associated with the cell wall lignification and polysaccharide composition of individual tissues.
Dietary NDF, regardless of plant source, have been identified as predictors of enteric methane (CH4) production. As digestibility of fiber increases, so does intake and ruminal fermentation, resulting in increased methane production [43]. However, the effect of carbohydrate type (structural or non-structural) on methane production is relatively less important at low intake levels [44]. Studies that have tried to explain how the NDF intake affects methane emissions have been inconclusive. Some independent studies have found that changes in NDF impact methane production without changes in intake [45][46], while others have found no difference in methane production for either changes in intake or NDF [47]. A meta-analysis of trials investigating NDF and methane in beef cattle found that NDF content alone does not explain enteric methane emissions. However, the quality and intake of the feed does impact methane emissions [48]. Therefore, by improving digestibility and nutritive value resulting in improved feed efficiencies will result in a reduction of methane emissions.

3. Cell Wall Biochemistry

Cell walls make up 23 to 90% of the plant mass [49] and are composed mainly of cellulose, hemicellulose, lignin, and other components, such as pectin and protein. Cell wall digestibility is variable and is negatively related to lignin concentration which is the primary limiting component of cell wall digestion [42]. Cell wall fibers that have high lignin and are linked to other structural carbohydrates are negatively associated with dry matter intake, dry matter digestibility, and animal performance [50].

3.1. Cellulose

Cellulose constitutes the largest portion of cell wall accounting for 40 to 50% of plant dry matter [51]. The yield of the stem and concentration of cellulose in the cell wall component of forage (fiber fraction) increase as alfalfa matures [40]. Although increases in stem mass and cellulose concentration in the cell wall theoretically increase the potential yield of digestible energy [26], the increase in lignin deposition during stem maturation and tight linkages of lignin with cellulose microfibrils substantially reduce microbial degradation of lignocellulosic biomass [52][53]. Rumen microflora have less than 50% access to plant fiber fractions [21] because of the heteromatrix complex formation between low-digestible lignin and high-energy cellulose [54]. The digestibility of cellulose is reduced when cellulose and lignin form these complex structures [55]. However, cellulose and hemicellulose are completely degraded when they do not have any bound lignin [56].

3.2. Hemicellulose

Hemicellulose is the second largest component of the alfalfa cell wall, constituting 15 to 20% of the forage dry matter [57]. Hemicellulose digestibility is more affected by cellulose digestion than lignin, despite the fact that hemicellulose and lignin being covalently linked [58]. Grass hemicellulose is more digestible by ruminants compared to cellulose, whereas the reverse is true for legumes [59]. Hemicellulose is characterized by complex structures built using monosaccharides such as xylose, galactose, mannose, and arabinose. Xylans have the slowest rate and extent of digestion [19][60] of all the hemicellulose components. A very strong negative relationship between xylose concentration and alfalfa in vitro degradability was reported indicating the vital role of xylan in inhibiting alfalfa digestibility [61]. Although xylans in legume cell walls are slowly degradable, its concentration in legumes is less than that in grasses [40]. A study found that xylan from alfalfa cell walls was the least digestible cell wall carbohydrate by sheep [62] and the same can be assumed for cattle. Low digestibility in mature grasses could be due to the linkage of xylan and lignin [62] that occur during plant maturity. No information is available about the effect of binding between xylan and cellulose on the degradation of these carbohydrates in the rumen [63].

3.3. Lignin

Lignin composes approximately 15% of the total dry matter of the alfalfa cell wall component, which limits cell wall degradation and forage digestibility by rumen microbes [64][65]. Lignin binds cellulose [66], xylose, arabinose, and mannose of heteroxylans of hemicellulose [67][68], which increase as alfalfa matures [69]. Cell wall digestibility is limited by lignin through the combination with cell wall components [70][71] and through the inhibition of phenolic acids such as p-coumaric acid, ferulic acid, and sinapic acid on rumen microbes [66][72][73]. These acids have inhibitory effects on rumen fungi, which limits the ability of fungi to degrade fibers in alfalfa and bermudagrass (Cynodon dactylon L. Pers.) [74]. Jung and Fahey [73] found that in vitro digestibility of cellulose and starch was depressed when supplied with p-coumaric, ferulic, salicylic, and vanillin acids. Some studies stated that lignin is indigestible [75][76][77][78] owing to the lack of known ruminal anaerobic fermentation [79], whereas others found that lignin is partially digestible in the abomasum with little change in the intestines [80]. During ruminal digestion of lignin, methane (22–29%), and carbon dioxide (65–69%) gases are produced, suggesting that ruminal digestion is relatively efficient compared to anerobic digesters [81]. Some studies have divided lignin into non-core lignin and core lignin monomers or polymers and number of covalent bonds [18][82]. Non-core lignins are monomers [83] and normally have one covalent linkage between a phenolic compound and either core lignin or hemicellulose [84], whereas core lignins are condensed and polymeric [85] and usually have two or more covalent bonds between monomers within its molecule [83]. Depending upon the lignin covalent links with carbohydrates, lignin can protect about 1.4 times its own mass of cell wall carbohydrates from microbial fermentation [86]. Another study found that lignin can protect two times its own mass of cell wall carbohydrates from microbial fermentation [87].
Alfalfa stems contain a variety of tissues with different patterns of cell wall development. The process of lignification varies between plant tissues. Some tissues, such as mesophyll in leaves, never lignify, whereas secondary xylem and other tissues accumulate high concentrations of lignin. About 6–9% of the dry weight of the whole alfalfa plant and 20% of the cell wall is lignin [88]. The lignin pathway was altered in alfalfa through decreasing the expression of two genes involved in the biosynthesis of coniferyl and sinapyl alcohol, which are considered as the main building blocks of lignin [28]. These changes in lignins were able to reduce 20% lignin within the plant which resulted in 2–5% increase in digestibility of the tissue. In contrast, conventional breeding takes more than 15 years of selection, which has resulted in a 2–3% increase in cell wall digestibility [89]. The relationship between in vivo dry matter digestibility and lignin was found to be significantly negative in alfalfa, when measured as acid detergent lignin [90].

3.4. Pectin

Pectin is a non-fibrous carbohydrate that accounts for 10–12% of the cell wall matrix in alfalfa stems. Pectin is completely digestible and is the cell wall polysaccharide most rapidly degradable by rumen microbes [60][91][92][93]. Selectively increasing easily digestible carbohydrates that make up the alfalfa cell wall, such as pectin, is a method to increase carbohydrate availability and hence improve protein utilization and alfalfa digestibility by ruminants [94][95][96]. About 20–35% and 1.0–10% of extractable pectic polysaccharides on a cell wall basis are present in legumes and in grasses, respectively [57]. Alfalfa leaves contain higher pectin concentrations than stems [60][97], and pectin concentration declines as stems mature [32][97]. However, pectin does not lower ruminal pH via lactate production, an intermediate product derived from microbial starch catabolism in the rumen, despite being a readily degradable source of energy in the rumen [98][99].
Neutral detergent soluble fiber (NDSF), in which pectic polysaccharides are the predominant components, can be used to estimate pectin concentration in alfalfa [97]. Variation in NDSF has been found in alfalfa [97][100]. Similarly, significant genetic variability for NDSF was reported in two alfalfa populations [101][102]. In addition, NDSF concentration was found to be negatively correlated with NDF, ADF, and acid detergent lignin (ADL) concentrations, whereas it positively correlated with in vitro dry matter digestibility (IVDMD) in alfalfa [102]. Similar results were found related to genetic improvement for NDSF concentration in five alfalfa populations, in which NDSF was found to be negatively correlated with total cell wall concentration (CW), and proportions of neutral detergent fiber (NDF), cellulose, and lignin in the CW, and positively correlated with crude protein concentration and IVDMD [103].

4. Alfalfa Morphology, Stem Tissue Development, and Lignification

As a perennial plant, alfalfa may proceed from the vegetative stage to seed production multiple times per growing season and over multiple years. The mass and height of alfalfa increases with plant maturity and the latter is associated with an increase in the number of stem internodes [40]. While the diameter of stem internodes continues to increase with plant maturity, the elongation of stem internodes ceases after approximately 21 days according to some reports and remains stable, or decreases in length over time [22][40]. The alfalfa leaf-to-stem ratio declines over time as stems proliferate with branching and defoliation due to leaf shading and foliar diseases. A defoliation event, such as grazing and mechanical harvest, can effectively reset alfalfa growth back to the vegetative stage.
In tandem with plant morphological development, the patterns of cell wall development of the different alfalfa stem tissues have been observed using microscopy. Alfalfa stem tissues follow different developmental pathways as they mature, which have implications for the degradability of stem cell walls. While some tissues, such as thin-walled chlorenchyma and thick-walled collenchyma, remain non-lignified and thus completely degradable in the presence of rumen microbes at all maturity stages; others like primary phloem fibers and pith parenchyma become lignified once stem elongation ceases and cambial activity begins [19][22][40]. Lignification occurs only in tissues with thickened secondary walls, including pith parenchyma, primary phloem fibers, and xylem tissues, with lignin deposition beginning in the primary cell wall and then proceeding into the secondary cell wall [22]. Xylem primary and secondary tissues immediately lignify making them impervious to degradation by rumen microbes [40]. Secondary xylem tissues arising from cambial activity comprise an increasing proportion of the stem as alfalfa matures, which helps to explain why stem lignin content increases with maturity [40]. At the same time, the concentration of pectin decreases while cellulose and hemicellulose concentrations increase in stem tissues contributing to the decline in alfalfa stem digestibility [40].

5. Methods to Increase Alfalfa Digestibility

Two common ways to increase digestibility of fiber in alfalfa are conventional breeding [31] and genetic engineering as reduced-lignin types [29]. Conventional breeding that used selection traits targeting the stems rather than the total biomass was found to have a greater impact on alfalfa digestibility owing to the presence of highly lignified fiber in stems [104]. Several studies have successfully used traditional breeding methods and genetic techniques to improve the digestibility in alfalfa cultivars. For example, the Hi-Gest alfalfa trait was developed by conventional breeding to improve total forage digestibility through increased leaf to stem ratio [105][106]. Conventional breeding improved fiber digestibility in alfalfa stem cell walls without diminishing dry matter yield, where populations were developed by recurrent phenotypic selection and evaluated by enzyme-released glucose as a proxy trait for fiber digestibility, indicating that selection was effective [107]. Alfalfa plants differed in stem NDF and ADL as a proportion of NDF (ADL/NDF) in another breeding program, in which plants were identified with either low or high rapid and low or high potential IVNDFD [25][30]. In contrast, the HarvXtra alfalfa (reduced lignin) was developed by genetic modification to improve nutritive value mainly through altering ADL and in vitro neutral detergent fiber digestibility (IVNDFD) in the stems [108][109]. Similar leaf-to-stem ratio and biomass yield between HarvXtra and conventional alfalfa cultivars was found through the evaluation of morphological characteristics in a single-location study [109]. One study conducted in multiple locations found higher leaf-to-stem ratio and increased stem digestibility but lower biomass yield in HarvXtra compared to conventional alfalfa [110]. Alfalfa breeding programs should emphasize stems when comparing nutritive value among whole plants, leaves, and stems because of the presence of the larger value of narrow-sense heritability for feeding-value traits in the stems [111], and they are the rate-limiting step for overall forage digestibility [23].

References

  1. Undersander, D. Economic Importance, Practical Limitations to Production, Management, and Breeding Targets of Alfalfa. In The Alfalfa Genome. Compendium of Plant Genomes; Yu, L.X., Kole, C., Eds.; Springer: Cham, Switzerland, 2021.
  2. Annicchiarico, P.; Barrett, B.; Brummer, E.C.; Bernadette Julier, B.; Marshall, A.H. Achievements and Challenges in Improving Temperate Perennial Forage Legume. Crit. Rev. Plant Sci. 2015, 34, 327–380.
  3. Tesfaye, M.; Silverstein, K.A.T.; Bucciarelli, B.; Samac, D.A.; Vance, C.P.; Tesfaye, M.; Silverstein, K.A.T.; Bucciarelli, B.; Samac, D.A.; Vance, C.P. The Affymetrix Medicago GeneChip® Array Is Applicable for Transcript Analysis of Alfalfa (Medicago sativa). Funct. Plant Biol. 2006, 33, 783–788.
  4. USDA National Agricultural Statistics Service. Available online: https://www.nass.usda.gov/Statistics_by_Subject/index.php?sector=CROPS (accessed on 1 September 2023).
  5. Fernandez, A.; Sheaffer, C.; Tautges, N.; Putnam, D. Alfalfa, Wildlife & the Environment, 2nd ed.; National Alfalfa and Forage Alliance: St. Paul, MN, USA, 2019.
  6. Barnes, R.; Collins, M. Forages: An Introduction to Grassland Agriculture; Iowa State Press: Ames, IA, USA, 2003.
  7. Bhandari, K.B.; West, C.P.; Acosta-Martinez, V. Assessing the role of interseeding alfalfa into grass on improving pasture soil health in semi-arid Texas High Plains. Appl. Soil Ecol. 2020, 147, 103399.
  8. Lauriault, L.M.; Guldan, S.J.; Martin, C.A. Evaluation of irrigated tall fescue-legume communities in the steppe of the southern Rocky Mountains: Years five to eight. Agron. J. 2003, 95, 1497–1503.
  9. Lauriault, L.M.; Guldan, S.J.; Martin, C.A.; VanLeeuwen, D.M. Performance of Irrigated Tall Fescue-Legume Communities under Two Grazing Frequencies in the Southern Rocky Mountains, USA. Crop Sci. 2006, 46, 330–336.
  10. Sheaffer, C.C.; Tanner, C.B.; Kirkham, M.B. Alfalfa water relations and irrigation. In Alfalfa and Alfalfa Improvement; Agronomy Monograph No. 29; Hanson, A., Barnes, D.K., Hill, R.R., Eds.; ASA-CSSA-SSSA: Madison, WI, USA, 1988; pp. 373–409.
  11. Ottman, M.J.; Tickes, B.R.; Roth, R.L. Alfalfa yield and stand response to irrigation termination in an arid environment. Agron. J. 1996, 88, 44–48.
  12. Lauriault, L.M.; Marsalis, M.A.; Contreras-Govea, F.; Angadi, S. Circular 646, Managing Alfalfa during Drought; Agricultural Experiment Station and Cooperative Extension Service, New Mexico State University: Las Cruces, Mexico, 2009; Available online: https://aces.nmsu.edu/pubs/_circulars/CR646.pdf (accessed on 1 September 2023).
  13. Cassida, K.A.; Stewart, C.B.; Haby, V.A.; Gunter, S.A. Alfalfa as an alternative to bermudagrass for pastured stocker cattle systems in the Southern USA. Agron. J. 2006, 98, 705–713.
  14. Heuschele, D.J.; Gamble, J.; Vetsch, J.A.; Shaeffer, C.C.; Coulter, J.A.; Kaiser, D.E.; Lamb, J.A.; Lamb, J.A.F.; Samac, D.A. Influence of potassium fertilization on alfalfa leaf and stem yield, forage quality, nutrient removal, and plant health. Agrosyst. Geosci. Environ. 2023, 6, e20346.
  15. Wilman, D.; Altimimi, M.A.K. The In-Vitro Digestibility and Chemical Composition of Plant Parts in White Clover, Red Clover and Lucerne during Primary Growth. J. Sci. Food Agric. 1984, 35, 133–138.
  16. de Ondarza, M.; Tricarico, J. Review: Advantages and Limitations of Dairy Efficiency Measures and the Effects of Nutrition and Feeding Management Interventions. Prof. Anim. Sci. 2017, 33, 393–400.
  17. Oba, M.; Allen, M.S. Evaluation of the Importance of the Digestibility of Neutral Detergent Fiber from Forage: Effects on Dry Matter Intake and Milk Yield of Dairy Cows. J. Dairy Sci. 1999, 82, 589–596.
  18. Buxton, D.R.; Russell, J.R. Lignin constituents and cell-wall digestibility of grass and legume stems. Crop Sci. 1988, 28, 553–558.
  19. Jung, H.G.; Engels, F.M. Alfalfa Stem Tissues: Rate and Extent of Cell-Wall Thinning during Ruminal Degradation. Neth. J. Agric. Sci. 2001, 49, 3–13.
  20. Mowat, D.N.; Fulkerson, R.S.; Tossell, W.E.; Winch, J.E. The in vitro digestibility and protein content of leaf and stem portions of foragers. Can. J. Plant Sci. 1965, 45, 321–331.
  21. Hatfield, R.D.; Ralph, J.; Grabber, J.H. Cell Wall Structural Foundations: Molecular Basis for Improving Forage Digestibilities. Crop Sci. 1999, 39, 27–37.
  22. Engels, F.M.; Jung, H.G. Alfalfa Stem Tissues: Cell-Wall Development and Lignification. Ann. Bot. 1998, 82, 561–568.
  23. Sheaffer, C.C.; Martin, N.P.; Lamb, J.A.F.S.; Cuomo, G.R.; Grimsbo Jewett, J.; Quering, S.R. Leaf and Stem Properties of Alfalfa Entries. Agron. J. 2000, 92, 733–739.
  24. Kephart, K.D.; Buxton, D.R.; Hill, R.R. Digestibility and Cell-Wall Components of Alfalfa Following Selection for Divergent Herbage Lignin Concentration. Crop Sci. 1990, 30, 207–212.
  25. Xu, Z.; Heuschele, D.J.; Lamb, J.A.F.S.; Jung, H.J.G.; Samac, D.A. Improved Forage Quality in Alfalfa (Medicago sativa L.) via Selection for Increased Stem Fiber Digestibility. Agronomy 2023, 13, 770.
  26. Lamb, J.A.F.S.; Jung, H.J.G.; Samac, D.A. Environmental Variability and/or Stability of Stem Fiber Content and Digestibility in Alfalfa. Crop Sci. 2014, 54, 2854–2863.
  27. Duceppe, M.O.; Bertrand, A.; Pattathil, S.; Miller, J.; Castonguay, Y.; Hahn, M.G.; Michaud, R.; Dubé, M.P. Assessment of Genetic Variability of Cell Wall Degradability for the Selection of Alfalfa with Improved Saccharification Efficiency. Bioenergy Res. 2012, 5, 904–914.
  28. Guo, D.; Chen, F.; Wheeler, J.; Winder, J.; Selman, S.; Peterson, M.; Dixon, R.A. Improvement of In-Rumen Digestibility of Alfalfa Forage by Genetic Manipulation of Lignin O-Methyltransferases. Transgenic Res. 2001, 10, 457–464.
  29. Mertens, D.R.; McCaslin, M. Evaluation of alfalfa hays with down-regulated lignin 270 biosynthesis. J. Dairy Sci. 2008, 91, 170.
  30. Jung, H.G.; Lamb, J.F.S. Stem Morphological and Cell Wall Traits Associated with Divergent In Vitro Neutral Detergent Fiber Digestibility in Alfalfa Clones. Crop Sci. 2006, 46, 2054–2061.
  31. Buxton, D.R.; Redfearn, D.D. Plant limitations to fiber digestion and utilization. J. Nutr. 1997, 127, 814S–818S.
  32. Jung, H.; Allen, M. Characteristics of plant cell walls affecting intake and digestibility of forages by ruminants. J. Anim. Sci. 1995, 73, 2774–2790.
  33. Smith, L.W.; Goering, H.K.; Gordon, C.H. Relationships of Forage Compositions with Rates of Cell Wall Digestion and Indigestibility of Cell Walls. J. Dairy Sci. 1972, 55, 1140–1147.
  34. Morrison, I.M. Carbohydrate Chemistry and Rumen Digestion. Proc. Nutr. Soc. 1979, 38, 269–274.
  35. Wilson, J.R. Organization of Forage Plant Tissues. In Forage Cell Wall Structure and Digestibility; Jung, H.G., Buxton, D.R., Hatfield, R.D., Ralph, J., Eds.; ASA-CSSA-SSSA: Madison, WI, USA, 1993; pp. 1–32.
  36. Engels, F.M.; Schuurmans, J.L.L. Relationship between Structural Development of Cell Walls and Degradation of Tissues in Maize Stems. J. Sci. Food Agric. 1992, 59, 45–51.
  37. Wilson, J.R. Influence of Plant Anatomy on Digestion and Fibre Breakdown. In Microbial and Plant Opportunities to Improve Lignocellulose Utilization by Ruminants; Akin, D.E., Ljungdahl, L.G., Wilson, J.R., Hams, P.J., Eds.; Elsevier: New York, NY, USA, 1990; pp. 99–117.
  38. Chesson, A.; Stewart, C.S.; Dalgarno, K.; King, T.P. Degradation of isolated grass mesophyll, epidermis and fibre cell walls in the rumen and by cellulolytic rumen bacteria in axenic culture. J. Appl. Bacteriol. 1986, 60, 327–336.
  39. Van Soest, P.J. The Detergent System for Analysis of Foods and Feeds; Cornell University: Ithaca, NY, USA, 2015; p. 176.
  40. Jung, H.G.; Engels, F.M. Alfalfa Stem Tissues: Cell Wall Deposition, Composition, and Degradability. Crop Sci. 2002, 42, 524–534.
  41. Jung, H.J.; Samac, D.A.; Sarath, G. Modifying crops to increase cell wall digestibility. Plant Sci. 2012, 185–186, 65–77.
  42. Jung, H.G.; Casler, M.D. Relationship of Lignin and Esterified Phenolics to Fermentation of Smooth Bromegrass Fibre. Anim. Feed Sci. Technol. 1991, 32, 63–68.
  43. Moraes, L.E.; Strathe, A.B.; Fadel, J.G.; Casper, D.P.; Kebreab, E. Prediction of enteric methane emissions from cattle. Glob. Chang. Biol. 2014, 20, 2140–2148.
  44. Moe, P.W.; Tyrrell, H.F. Methane production in dairy cows. J. Dairy Sci. 1979, 62, 1583–1586.
  45. Primavesi, O.; Frighetto, R.T.S.; Pedreira, M.S.; Lima, M.A.; Berchielli, T.T.; Rodrigues, A.A. Low-fiber sugarcane to improve meat production with less methane emission in tropical dry season. In Proceedings of the 3rd International Methane and Nitrous Oxide Mitigation Conference, Beijing, China, 14–19 September 2003; pp. 185–189.
  46. Aguerre, M.J.; Wattiaux, M.A.; Powell, J.M.; Broderick, G.A.; Arndt, C. Effect of forage-to-concentrate ratio in dairy cow diets on emission of methane, carbon dioxide, and ammonia, lactation performance, and manure excretion. J. Dairy Sci. 2011, 94, 3081–3093.
  47. Hammond, K.J.; Crompton, L.A.; Bannink, A.; Dijkstra, J.; Yáñez-Ruiz, D.R.; O’Kiely, P.; Kebreab, E.; Eugène, M.A.; Yu, Z.; Shingfield, K.J.; et al. Review of current in vivo measurement techniques for quantifying enteric methane emission from ruminants. Anim. Feed Sci. Technol. 2016, 219, 13–30.
  48. Santander, D.; Clariget, J.; Banchero, G.; Alecrim, F.; Simon Zinno, C.; Mariotta, J.; Gere, J.; Ciganda, V.S. Beef Steers and Enteric Methane: Reducing Emissions by Managing Forage Diet Fiber Content. Animals 2023, 13, 1177.
  49. Lee, Y.; Yoon, T.H.; Lee, J.; Jeon, S.J.; Lee, J.H.; Lee, M.K.; Chen, H.; Yun, J.; Oh, S.Y.; Wen, X.; et al. A Lignin Molecular Brace Controls Precision Processing of Cell Walls Critical for Surface Integrity in Arabidopsis. Cell 2018, 173, 1468–1480.
  50. Dehority, B.A.; Johnson, R.R. Effect of Particle Size upon the in Vitro Cellulose Digestibility of Forages by Rumen Bacteria. J. Dairy Sci. 1961, 44, 2242–2249.
  51. Delmer, D.P.; Amor, Y. Cellulose biosynthesis. Plant Cell 1995, 7, 987–1000.
  52. Avgerinos, G.C.; Wang, D.I. Selective solvent delignification for fermentation enhancement. Biotechnol. Bioeng. 1983, 25, 67–83.
  53. Jung, H.G.; Jorgensen, M.A.; Linn, J.G.; Engels, F.M. Impact of Accessibility and Chemical Composition on Cell Wall Polysaccharide Degradability of Maize and Lucerne Stems. J. Sci. Food Agric. 2000, 80, 419–427.
  54. Bajpai, P. Pretreatment of lignocellulosic biomass for biofuel production. In Green Chemistry for Sustainability; Sharma, S.K., Ed.; Springer briefs in molecular science; Springer: Jaipur, India, 2016; pp. 7–12.
  55. Lodish, H.; Berk, A.; Zipursky, S.L.; Matsudaira, P.; Baltimore, D.; Darnell, J. Photosynthetic Stages and Light-Absorbing Pigments. In Molecular Cell Biology, 4th ed.; Freeman, W.H., Ed.; References-Scientific Research Publishing: New York, NY, USA, 2000; Available online: https://scirp.org/reference/referencespapers.aspx?referenceid=2396444 (accessed on 14 September 2023).
  56. McLeod, M.N.; Minson, D.J. Predicting dry matter digestibility from acid detergent fibre levels in grasses as affected by a pretreatment with neutral detergent. J. Sci. Food Agric. 1974, 25, 913–917.
  57. Mohnen, D.; Keegstra, K.; Pauly, M. Pectin Structure and Biosynthesis This Review Comes from a Themed Issue on Physiology and Metabolism Edited. Curr. Opin. Plant Biol. 2008, 11, 266–277.
  58. Jung, H.G.; Vogel, K.P. Influence of Lignin on Digestibility of Forage Cell Wall Material. J. Anim. Sci. 1986, 62, 1703–1712.
  59. Wedig, C.L.; Jaster, E.H.; Moore, K.J. Hemicellulose Monosaccharide Composition and in Vitro Disappearance of Orchard Grass and Alfalfa Hay. J. Agric. Food Chem. 1987, 35, 214–218.
  60. Hatfield, R.D.; Weimer, P.J. Degradation Characteristics of Isolated and in Situ Cell Wall Lucerne Pectic Polysaccharides by Mixed Ruminal Microbes. J. Sci. Food Agric. 1995, 69, 185–196.
  61. Nordkvist, E.; Åman, P. Changes during Growth in Anatomical and Chemical Composition and In-Vitro Degradability of Lucerne. J. Sci. Food Agric. 1986, 37, 1–7.
  62. Ben-Ghedalia, D.; Miron, J. The digestion of total and cell wall monosaccharides of alfalfa by sheep. J. Nutr. 1984, 114, 880–887.
  63. Albrecht, K.A.; Wedin, W.F.; Buxton, D.R. Cell-wall composition and digestibility of lucerne stems and leaves. Crop Sci. 1987, 27, 735–741.
  64. Fukushima, R.S.; Kerley, M.S.; Ramos, M.H.; Porter, J.H.; Kallenbach, R.L. Comparison of Acetyl Bromide Lignin with Acid Detergent Lignin and Klason Lignin and Correlation with in Vitro Forage Degradability. Anim. Feed Sci. Technol. 2015, 201, 25–37.
  65. Jung, H.G.; Deetz, D.A. Chapter 13 Cell Wall Lignification and Degradability. In Forage Cell Wall Structure and Digestibility; ASA-CSSA-SSSA: Madison, WI, USA, 1993.
  66. Jung, H.G.; Fahey, G.C. Nutritional Implications of Phenolic Monomers and Lignin: A Review. J. Anim. Sci. 1983, 57, 206–219.
  67. Lawoko, M.; Henriksson, G.; Gellerstedt, G. Structural Differences between the Lignin-Carbohydrate Complexes Present in Wood and in Chemical Pulps. Biomacromolecules 2005, 6, 3467–3473.
  68. Mueller-Harvey, I.; Hartley, R.D.; Harris, P.J.; Curzon, E.H. Linkage of p-coumaroyl and feruloy groups to cell-wall polysaccharides of barley straw. Carbohydr. Res. 1986, 148, 71–85.
  69. Bailey, R.W. Structural carbohydrates. In Chemistry and Biochemistry of Herbage; Butler, G.W., Bailey, R.W., Eds.; Academic Press: New York, NY, USA, 1973; Volume 1, pp. 157–211.
  70. Jung, H.G. Forage Lignins and Their Effects on Fiber Digestibility. Agron. J. 1989, 81, 33–38.
  71. Morrison, I.M. Structural Investigations on the Lignin–Carbohydrate Complexes of Lolium perenne. Biochem. J. 1974, 139, 197.
  72. Grabber, J.H.; Ralph, J.; Hatfield, R.D.; Quideau, S. P-Hydroxyphenyl, Guaiacyl, and Syringyl Lignins Have Similar Inhibitory Effects on Wall Degradability. J. Agric. Food Chem. 1997, 45, 2530–2532.
  73. Jung, H.-J.G.; Fahey, G.C. Interactions Among Phenolic Monomers and In Vitro Fermentation. J. Dairy Sci. 1983, 66, 1255–1263.
  74. Akin, D.E.; Rigsby, L.L. Influence of phenolic acids on rumen fungi. Agron. J. 1985, 77, 180–182.
  75. Arora, D.S.; Sharma, R.K. Enhancement in in vitro digestibility of wheat straw obtained from different geographical regions during solid state fermentation by white rot fungi. Bioresources 2009, 4, 909–920.
  76. Falcón, M.A.; Rodríguez, A.; Carnicero, A.; Regalado, V.; Perestelo, F.; Milstein, O.; De la Fuente, G. Isolation of Microorganisms with Lignin Transformation Potential from Soil of Tenerife Island. Soil Biol. Biochem. 1995, 27, 121–126.
  77. Kara, E.; Sürmen, M. The Effects of Secondary Metabolites of Rangeland and Pasture Plants on the Animal Health in Mediterranean Ecological Conditions. J. US China Med. Sci. 2019, 16, 63–72.
  78. Li, X.; Kellaway, R.C.; Ison, R.L.; Annison, G. Chemical composition and nutritive value of mature annual legumes for sheep. Anim. Feed Sci. Technol. 1992, 37, 221–231.
  79. van Kuijk, S.J.A.; Sonnenberg, A.S.M.; Baars, J.J.P.; Hendriks, W.H.; Cone, J.W. Fungal Treatment of Lignocellulosic Biomass: Importance of Fungal Species, Colonization and Time on Chemical Composition and in Vitro Rumen Degradability. Anim. Feed Sci. Technol. 2015, 209, 40–50.
  80. Fahey, G.C.; McLaren, G.A.; Williams, J.E. Lignin Digestibility by Lambs Fed Both Low Quality and High Quality Roughages. J. Anim. Sci. 1979, 48, 941–946.
  81. Bayané, A.; Guiot, S.R. Animal digestive strategies versus anaerobic digestion bioprocesses for biogas production from lignocellulosic biomass. Rev. Environ. Sci. Bio/Technol. 2011, 10, 43–62.
  82. Lapierre, C. Application of New Methods for the Investigation of Lignin Structure. In ASA, CSSA, and SSSA Books; Wiley Online Library: Hoboken, NJ, USA, 1993; Available online: https://acsess.onlinelibrary.wiley.com/doi/abs/10.2134/1993.foragecellwall.c6 (accessed on 14 September 2023).
  83. Theander, O.; Aman, P. Anatomical and chemical characteristics. In Straw and Other Fibrous By-Products as Feed; Sundstol, F., Owen, E., Eds.; Elsevier: Amsterdam, The Netherlands, 1984; pp. 45–78.
  84. Ralph, J.; Helm, R.F. Lignin/Hydroxycinnamic Acid/Polysaccharide Complexes: Synthetic Models for Regiochemical Characterization. In Forage Cell Wall Structure and Digestibility; ASA-CSSA-SSSA: Madison, WI, USA, 2015; pp. 201–246.
  85. Ganewatta, M.S.; Lokupitiya, H.N.; Tang, C. Lignin Biopolymers in the Age of Controlled Polymerization. Polymers 2019, 11, 1176.
  86. Van Soest, P.J. Limiting Factors in Plant Residues of Low Biodegradability. Agric. Environ. 1981, 6, 135–143.
  87. Grabber, J.H. How Do Lignin Composition, Structure, and Cross-Linking Affect Degradability? A Review of Cell Wall Model Studies. Crop Sci. 2005, 45, 820–831.
  88. Hatfield, R.D.; Jung, H.J.; Broderick, G.; Jenkins, T. Nutritional Chemistry of Forages. In Forages, the Science of Grassland Agriculture; Barnes, R.F., Ed.; Blackwell Pub.: Ames, IA, USA, 2007.
  89. Martin, N.P.; Mertens, D.R. Reinventing alfalfa for dairy cattle and novel uses. In Proceedings of the California Alfalfa and Forage Symposium, Visalia, CA, USA, 12–14 December 2005.
  90. Kondo, T.; Mizuno, K.; Kato, T. Some Characteristics of Forage Plant Lignin. Jpn. Agric. Res. Q. 1987, 21, 47–52.
  91. Hatfield, R.D. Cell wall polysaccharide interactions and degradability. In Forage Cell Wall Structure and Digestibility; Jung, H.G., Buxton, D.R., Hatfield, R.D., Ralph, J., Eds.; ASA-CSSA-SSSA: Madison, WI, USA, 1993; pp. 286–313.
  92. Jung, H.J.G. Analysis of Forage Fiber and Cell Walls in Ruminant Nutrition. J. Nutr. 1997, 127, 810S–813S.
  93. Sniffen, C.J.; O’Connor, J.D.; Van Soest, P.J.; Fox, D.G.; Russell, J.B. A Net Carbohydrate and Protein System for Evaluating Cattle Diets: II. Carbohydrate and Protein Availability. J. Anim. Sci. 1992, 70, 3562–3577.
  94. Van Soest, P.J. What constitutes alfalfa quality: New considerations. In Proceedings of the 25th National Alfalfa Symposium, Liverpool, NY, USA, 27–28 February 1995; pp. 1–15.
  95. Viands, D.R. What breeding objectives really will improve forage quality of alfalfa? In Proceedings of the 25th National Alfalfa Symposium, Liverpool, NY, USA, 27–28 February 1995; pp. 24–28.
  96. McCormick, M.E.; Redfearn, D.D.; Ward, J.D.; Blouin, D.C. Effect of Protein Source and Soluble Carbohydrate Addition on Rumen Fermentation and Lactation Performance of Holstein Cows. J. Dairy Sci. 2001, 84, 1686–1697.
  97. Hall, M.; Lewis, B.; Soest, P.V.; Chase, L. A Simple Method for Estimation of Neutral Detergent-Soluble Fibre. J. Sci. Food Agric. 1997, 74, 441–449.
  98. Ben-Ghedalia, D.; Yosef, E.; Miron, J.; Est, Y. The effects of starch- and pectin-rich diets on quantitative aspects of digestion in sheep. Anim. Feed Sci. Technol. 1989, 24, 289–298.
  99. Strobel, H.J.; Russell, J.B. Effect of pH and Energy Spilling on Bacterial Protein Synthesis by Carbohydrate-Limited Cultures of Mixed Rumen Bacteria. J. Dairy Sci. 1986, 69, 2941–2947.
  100. Hall, M.B.; Hoover, W.H.; Jennings, J.P.; Webster, T.K.M. A method for partitioning neutral detergent soluble carbohydrates. J. Sci. Food Agric. 1999, 79, 2079–2086.
  101. Fonseca, C.E.L.; Viands, D.R.; Hansen, J.L.; Pell, A.N. Associations among Forage Quality Traits, Vigor, and Disease Resistance in Alfalfa. Crop Sci. 1999, 39, 1271–1276.
  102. Fonseca, C.E.L.; Hansen, J.L.; Thomas, E.M.; Pell, A.N.; Viands, D.R. Near Infrared Reflectance Spectroscopy Prediction and Heritability of Neutral Detergent-Soluble Fiber in Alfalfa. Crop Sci. 1999, 39, 1265–1270.
  103. Tecle, I.Y.; Viands, D.R.; Hansen, J.L.; Pell, A.N. Response from Selection for Pectin Concentration and Indirect Response in Digestibility of Alfalfa. Crop Sci. 2006, 46, 1081–1087.
  104. Buxton, D.R.; Marten, G.C.; Hornstein, J.S. Genetic variation for forage quality of alfalfa stems. Can. J. Plant Sci. 1987, 67, 057–1067.
  105. Damiran, D.; Biligetu, B.; Pearce, L.; Lardner, H. PSXI-15 Evaluation of low-lignin alfalfa Hi-Gest® 3600 on the Canadian prairies: Productivity, nutrient profile, and rumen degradation kinetics. J. Anim. Sci. 2021, 99, 348.
  106. Jungers, J.; Cherney, J.; Martinson, K.; Jaqueth, A.; Sheaffer, C. Forage Nutritive Value of Modern Alfalfa Cultivars. Crop Forage Turfgrass Manag. 2020, 6, e20076.
  107. Bertrand, A.; Claessens, A.; Thivierge, M.; Rocher, S.; Lajeunesse, J.; Castonguay, Y.; Seguin, P. Field Assessment of Alfalfa Populations Recurrently Selected for Stem Cell Wall Digestibility. Crop Sci. 2018, 58, 1632–1643.
  108. Grev, A.M.; Scott Wells, M.; Samac, D.A.; Martinson, K.L.; Sheaffer, C.C. Forage Accumulation and Nutritive Value of Reduced Lignin and Reference Alfalfa Cultivars. Agron. J. 2017, 109, 2749–2761.
  109. Grev, A.M.; Wells, M.S.; Catalano, D.N.; Martinson, K.L.; Jungers, J.M.; Sheaffer, C.C. Stem and leaf forage nutritive value and morphology of reduced lignin alfalfa. Agron. J. 2020, 112, 406–417.
  110. Arnold, A.M.; Cassida, K.A.; Albrecht, K.A.; Hall, M.H.; Min, D.; Xu, X.; Orloff, S.; Undersander, D.J.; Santen, E.; Sulc, R.M. Multistate Evaluation of Reduced-Lignin Alfalfa Harvested at Different Intervals. Crop Sci. 2019, 59, 1799–1807.
  111. Milić, D.; Karagić, D.; Vasiljević, S.; Mikić, A.; Milošević, B.; Katić, S. Breeding and Improvement of Quality Traits in Alfalfa (Medicago sativa ssp Sativa L.). Genet.-Belgrade 2014, 46, 11–18.
More
Information
Contributors MDPI registered users' name will be linked to their SciProfiles pages. To register with us, please refer to https://encyclopedia.pub/register : , ,
View Times: 199
Revisions: 2 times (View History)
Update Date: 30 Nov 2023
1000/1000
ScholarVision Creations