Soluble phenolic compounds of perennial ryegrass (Lolium perenne L.): potential effects on animal performance, and challenges in determining profiles and concentrations

Authors: Kagan, Isabelle

Submitted to: Animal Feed Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/27/2021
Publication Date: 5/2/2021
Citation: Kagan, I. 2021. Soluble phenolic compounds of perennial ryegrass (Lolium perenne L.): potential effects on animal performance, and challenges in determining profiles and concentrations. Animal Feed Science and Technology. 277. Article 114960. https://doi.org/10.1016/j.anifeedsci.2021.114960.
DOI: https://doi.org/10.1016/j.anifeedsci.2021.114960

Interpretive Summary: Phenolic compounds are natural products that are found in many plants, including grasses. Perennial ryegrass contains phenolic compounds that are bound to cell walls, and phenolic compounds that are soluble (not bound to cell walls). The soluble phenolic compounds may be beneficial to animals consuming the perennial ryegrass, based on studies in the literature showing benefits of phenolic compounds to grazing animals. Determining the roles of phenolic compounds in animal performance requires an understanding of their structures and the amounts present. This review covers the current knowledge of types and amounts of perennial ryegrass soluble phenolic compounds. Some compounds have been characterized, and others have both known and unknown components. Types and amounts of phenolic compounds present are affected by the way that samples are handled, the presence of fungi, environmental stresses, time of sample collection, and the varieties of perennial ryegrass studied. All of these factors create challenges in determining what phenolic compounds are present and whether they play a role in animal performance on perennial ryegrass. Consistent methods across studies are needed, as are larger amounts of material to facilitate identifying compounds present in small amounts.

Technical Abstract: Perennial ryegrass (Lolium perenne L.) contains phenolic compounds esterified to cell walls, and it also contains soluble phenolic compounds in the vacuole. Soluble phenolic compounds of perennial ryegrass may be important to the performance of grazing animals, due to their roles as substrates for polyphenol oxidase and as antioxidants. However, the soluble phenolic compound profile of perennial ryegrass has not been completely identified, making it difficult to determine which compounds could be important for animal performance. This review addresses the current state of knowledge of perennial ryegrass phenolic compound composition and concentration. Chlorogenic acid and its isomers have been characterized in many varieties of perennial ryegrass, as has thesinine rhamnoside. Many glycosides of various flavonoids have been reported, but the glycosidic moieties have not been completely characterized Condensed tannins have been found in seeds, but their presence in leaf tissue has been variable. Concentration and composition of soluble phenolic compounds of perennial ryegrass are affected by sample preparation, presence of pathogens or endophytes, environmental stresses, time of day, and genetic background. The challenges in characterizing the soluble phenolic compounds of perennial ryegrass lie in the difficulties of comparing results across studies, due to the abovementioned sources of variation, and in the need for consistent extraction methods, separation methods, and adequate amounts of material.