Associative effects of forage diversity on herbage nutritive value, and total flavonoid and polyphenol contents in forages and ruminal fluid

Abstract We evaluated the effects of forage diversity on nutritional value, secondary metabolites and ruminal fermentation parameters. Five treatments with increasing forage diversity—Grass (G), Grass + Legume (GL), Grass + Legume + Forb (GLF; three species), GLF‐6 (six species; two species per group) and GLF‐9 (nine species; three species per group)—were cultivated and analyzed for nutritional composition, secondary metabolites, in vitro digestibility, gas production and ruminal fermentation characteristics. Dry matter (DM), crude protein (CP) and neutral detergent fiber (aNDFom) varied among treatments, with numerically higher CP in GLF and GLF‐9 and lower DM in GLF and GLF‐9. Total phenolic and flavonoid contents also varied, with quercetin, luteolin, and kaempferol numerically increasing in GLF‐6 and GLF‐9, and rutin decreasing from 294.82 μg/g DM in G to 89.89 μg/g DM in GLF‐9. In vitro digestibility, total gas and methane production, short‐chain fatty acids and ruminal pH were not significantly affected by forage diversity based on quadratic regression analysis. Rutin in forage was almost undetectable in ruminal fluid. Overall, increasing forage species diversity did not substantially impact forage nutritional composition, digestibility or ruminal fermentation characteristics.