Symposium review: Technologies for improving fiber utilization

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 expansinlike 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 onfarm applicability of technologies for increasing fiber utilization.

The role of homofermentative and heterofermentative lactic acid bacteria for alfalfa silage: a meta-analysis

“…The NDF and ADF of silages are important quality parameters and are expected to be lower in inoculated alfalfa. Certain inoculants contain bacteria that could secrete specific enzymes, mainly cellulases and xylanases, that may contribute to degrade these structures and increased fibre digestion (Adesogan et al ., 2019). The decreased NDF and ADF concentration could be also related to better WSC preservation following inoculation, which could reduce NDF and ADF contents by a ‘dilution effect’.…”

Feeding Fungal-Pretreated Corn Straw Improves Health and Meat Quality of Lambs Infected with Gastrointestinal Nematodes

“…Of the many approaches to the improvement of straw digestibility, biologic fermentation techniques seem to be the best. Compared to physical and/or chemical treatments, biologic treatment has definite advantages in terms of energy consumption and avoidance of toxic chemicals [ 12 ]. The WRF are commonly used for straw pretreatment to increase fiber digestibility, probably due to their secreted oxidative ligninolytic enzymes including laccase, manganese peroxidase and lignin peroxidase to decompose lignin [ 13 ].…”

Strategies to improve the efficiency of beef cattle production

“…Improving dietary fibre degradation is important for improving efficiency as fibre can limit intake and diet digestibility. Mechanical processing including chopping, shredding, and pelleting can increase the surface area for microbial attachment, reduce gut fill, and increase feed intake (Adesogan et al 2019). Alkali treatment is also an effective method for breaking down the fibrous components that restrict microbial degradation.…”