This work addresses the dynamic of phenological development on mean stage weight (MSW), chemical composition, (ash, nitrogen (N), neutral detergent fibre (NDF) and acid detergent fibre (ADF) contents, and pepsin-cellulase dry matter digestibility (PCDMD) for cultivars of six perennial grass species (timothy, ryegrass, cocksfoot, sheep’s fescue, red fescue and meadow foxtail), during their first growth cycle. The study was performed over two years along 3 sites distributed along an altitudinal gradient. The dynamics of MSW, N, NDF, ADF and PCDMD for the species differed according to the environment. For a given sum of temperatures, at Clermont-Ferrand (CL; 350 m), MSW was delayed (note of 2.37) compared with Saint-Genès-Champanelle (SG; 850 m; note of 2.97) and Laqueuille (LA; 1100 m; note of 3.02). Consequently, the NDF and ADF contents were lower and the PCDMD value was higher in the cultivars established at CL (575 g/kg dry matter (DM), 287 g/kg DM and 0.64 respectively) than in those at SG (653 g/kg DM, 349 g/kg DM and 0.51 respectively) and LA (653 g/kg DM, 343 g/kg DM and 0.52 respectively). In all sites, and for the two years, the PCDMD content of timothy (0.60), ryegrass (0.63) and cocksfoot (0.59) cultivars were higher than that of sheep’s fescue (0.47), red fescue (0.53), and meadow foxtail (0.51). The only exception was identified for CL site in the first year of the study, when the dynamic of PCDMD was similar for all cultivars. Sum of temperatures and MSW were closely related to nutritive value of forage, but neither indicator fully described the nutritive value of perennial grasses.

CL 栽培品种的 NDF 和 ADF 含量较低，PCDMD 值较高（分别为 575 g/kg 干物质（DM）、287 g/kg DM 和 0.64）比 SG 栽培品种（653 g/kg DM） ，分别为 349 g/kg DM 和 0.51）和 LA（分别为 653 g/kg DM、343 g/kg DM 和 0.52）。在所有地点，两年内，蒂莫西 (0.60)、黑麦草 (0.63) 和鸡脚 (0.59) 品种的 PCDMD 含量高于羊茅 (0.47)、红羊茅 (0.53) 和草甸狗尾草 ( 0.51）。唯一的例外是在研究的第一年发现 CL 站点，当时所有品种的 PCDMD 动态相似。温度和MSW的总和与牧草的营养价值密切相关，但两个指标都不能完全描述多年生牧草的营养价值。