To evaluate the influence of maturity stage of herbage on possible changes in chemical composition and in vitro organic matter digestibility (IVOMD) of extrusae from oesophageally- fistulated sheep compared to the corresponding feed sample, four trials were conducted with freshly cut herbage samples of a Lolium-Festuca-Trifolium sward in May, June, July and September. Sixteen oesophageally-fistulated Churra ewes were assigned to four balanced groups of four animals. One animal from each group was assigned to a trial. Samples of 250 g of herbage were fed to each animal in the morning of the three days of each period. There were no refusals. Moisture and ash contents were higher (P < 0.01) in extrusa than in herbage samples in all the periods. The nitrogen (N) content of extrusa samples were up to 19.2 and 8.6% higher than in corresponding herbage samples in May and June, respectively. A significant decrease of 7.8% in extrusae N content occurred in July, while and the 5% difference between extrusae and herbage observed in September was not significant (P > 0.10). Differences in NDF, ADF and cellulose between extrusa and herbage samples were significant (P < 0.01) only in July. Lignin concentration in extrusae was higher (P < 0.05) than in herbage samples in May and a significant (P < 0.05) decrease in lignin content was observed in July and September. A small but significant (P < 0.05) increase in the IVOMD value of extrusae was obtained in May.