Measurement of Nutritive Value and Phenolic Compounds in Forage Plants Used in Animal Production

Secondary metabolites are important organic metabolites produced by plants. These metabolites include phenolic compounds, which have been of research interest because phenolics are considered an antinutritional factor for ruminants, compromise the bioavailability of nutrients. This study included a chemical composition analysis, an analysis of the condensed tannin content and the identification and quantification of the phenolic compounds present in the following plants cultivated with and without fertilisation: Coastcross-1 grass (G) and the legumes Stylosanthes guianensis cv. Mineirão (MS), Stylosanthes capitata × Stylosanthes macrocephala cv. Campo Grande (CGS), Arachis pintoi cv. Amarillo (AA) and Arachis pintoi cv. Belmonte (AB). High-performance liquid chromatography (HPLC) was used to analyse 13 phenolic compounds. The forage with the best nutritive value was Amarillo pinto peanut. The condensed tannin content was higher in the legumes than that in the grass. Vanillin and o-coumaric, m-coumaric, caffeic and ferulic acid were detected in all the cultivars. The cultivar with the largest variety of phenolic compounds was Coastcross-1 grass. Diversity existed in the occurrence of phenolic compounds, which indicated the presence of condensed tannins in the cultivars and possibly that the diversity does not affect the concentration of these compounds. The AA cultivar was the most interesting alternative for the establishment of pasture intercropped with Coastcross-1 grass.