Phenological Effects on Forage Quality of Five Grass Species

Information on nutritive values of each plant part in each phenological stage could help range managers choose suitable grazing times to achieve higher animal performance without detriment to vegetation. Thus, nutritive value of different plant parts of 5 grass species in 3 phenological stages (vegetative, flowering, and seed production) from 2 sites were investigated. Species included: Agropyron tauri Boiss and Bal., Agropyron trichophorum Richt, Bromus tomentellus Boiss, Festuca ovina Hack, and Hordeum bulbosum L. Samples of leaf, stem, and flower from 5 locations at each site for each species were analyzed for dry matter ratio of plant parts, crude protein, acid detergent fiber, neutral detergent fiber, dry matter digestibility, and metabolizable energy. A completely randomized design with a factorial arrangement of species and phenological stage was analyzed with 5 replicates for each location. Plant part was included as a subplot factor in a split plot arrangement. Nutritive values differed significantly (P < 0.05) both within and among plant parts and phenological stages for each species. Phenological stages indicated a significant difference on nutritive value of plant parts, with leaves having the highest nutritive value. Thus, forage with a higher leaf-to-stem ratio should improve animal performance because at the beginning of the 2nd phenological stage, the plant had desirable quantity and quality of forage with higher leaf-to-stem ratio.