Improvement of Ruminal Neutral Detergent Fiber Degradability by Obtaining and Using Exogenous Fibrolytic Enzymes from White-Rot Fungi

Abstract

The present review examines the factors and variables that should be considered to obtain, design, and evaluate EFEs that might enhance ruminal NDF degradability. Different combinations of words were introduced in Google Scholar, then scientific articles were examined and included if the reported factors and variables addressed the objective of this review. One-hundred-and-sixteen articles were included. The fungal strains and culture media used to grow white-rot fungi induced the production of specific isoforms of cellulases and xylanases; therefore, EFE products for ruminant feed applications should be obtained in cultures that include the high-fibrous forages used in the diets of those animals. Additionally, the temperature, pH, osmolarity conditions, and EFE synergisms and interactions with ruminal microbiota and endogenous fibrolytic enzymes should be considered. More consistent results have been observed in studies that correlate the cellulase-to-xylanase ratio with ruminant productive behavior. EFE protection (immobilization) allows researchers to obtain enzymatic products that may act under ruminal pH and temperature conditions. It is possible to generate multi-enzyme cocktails that act at different times, re-associate enzymes, and simulate natural protective structures such as cellulosomes. Some EFEs could consistently improve ruminal NDF degradability if we consider fungal cultures and ruminal environmental conditions variables, and include biotechnological tools that might be useful to design novel enzymatic products.

Evaluation of the efficacy of varying xylanase to cellulase ratio on ruminal fermentation of untreated and alkali treated oat straw

“…Therefore, the in vitro anaerobic ruminal fermentation technique was used as an alternative, which provides a quick, pro [31] and making the feed more susceptible to ruminal degradation and microbial colonization [32]. Enzymatic additives may also interact synergistically with endogenous enzymes of ruminal microbes [30,31]. The precise mechanisms for the EFE detrimental effect are not well known, but it could be related to the excess enzymatic concentration in the ruminal environment, which may inhibit microbial enzyme production, block enzyme binding sites [33], or decrease the microbial e ciency to attach the feed and degrade the feed structure [34].…”

“…[42] suggested that the chemical pre-treatment of wheat straw and rice straw enhanced the e cacy of EFE on ruminant fermentation and dry matter digestibility and acted synergistically with urea pre-treatment to improve the digestive use of brous by-products. Some other potential factors could in uence the e cacy of cellulases and xylanases supplementation, such as the molecular weight of brolytic components, the proteolytic stability within the digestive tract, ruminal conditions, the ingredients of the diets, and the forage-to-concentrate ratios [30,43].…”

A Review on the Role of Exogenous Fibrolytic Enzymes in Ruminant Nutrition

“…Possible mode of action of EFE can be explained through their effect on feed before consumption or through improvement of digestion within the rumen and/or their impact at post ruminal digestive tract. Effect of EFE on feed before consumption may be simple to complex like release of soluble carbohydrate, release or removal of structural barriers of feed which restrict microbial digestion in the rumen [24,32]. In the rumen, EFE may act directly on feed or indirectly may work synergistically with rumen microbes.…”

Effects of <i>Stylosanthes scabra</i> Forage Supplementation on <i>in Vitro</i> Gas Production and Fiber Degradation of <i>Eragrostis</i> Grass Hay

“…Hence, it is used as common measure of fiber content required in animal feed [19]. Therefore, NDF level above 65% in the feed may reduce dry matter intake [20], and that may lead to an adverse effect on potential milk and meat production and quality [21]. According to Tirado-Estrada et al [22], NDF proportion and degradability of the forage can be used to predict the dry matter intake and productive performance of the animal.…”