Two experiments were conducted to evaluate the effects of a fibrolytic enzyme preparation on the nutritive value of lucerne for equids. In both experiments four mature Welsh-cross pony geldings were used in a 4 X 4 Latin-square design to assess the effect of a fibrolytic enzyme treatment on the nutritive value of either high-temperature dried (HT) lucerne (experiment 1) or ensiled lucerne (experiment 2) for equids. Experiment 1 consisted of four levels of enzyme treatment (0 [WC], 2.3 [DE 1], 4.7 [DE2] and 8.9 L tonne 1 dry matter (DM) [DE3]), whilst in experiment 2 the four levels of enzyme treatment were: 0 (WS), 2.7 (WE1), 5.5 (WE2) and 10.2 L tonne(-1) DM (WE3). Each diet was fed to give a DM intake of 17.5 g kg(-1) of liveweight per day, offered in two equal meals at 12 h intervals. Digestibility was determined by total faecal collection. Feed and faecal samples were analysed for DM, OM, CP, ADFom, NDFom, starch, WSC, GE, Na, Ca, P, K, Mg and non-starch polysaccharide (NSP) content and composition. Silages were also analysed for pH, VIA, lactate, TN, ammonia-N and aerobic stability. In experiment 1, enzyme treatment significantly (P<0.001) reduced total NSP digestibility (TNSPD) at the lower levels of application in comparison to the control (551, 578 and 608 g kg(-1) for DE1, DE2 and WC, respectively), whilst in experiment 2, TNSPD was significantly (P<0.001) reduced at the higher application level compared to the control (550 and 421 g kg for WE3 and WS, respectively). The DM contents of the enzyme-treated silages were significantly lower (averaging 269 g kg) compared to the control (302 g kg 1) and butyrate content increased significantly (P<0.05) with increasing level of enzyme (2.6, 4.4, 7.8 and 7.8 g kg(-1) DM for WS, WE1, WE2 and WE3, respectively). Consequently, enzyme treatment does not appear to increase the nutritive value of high-temperature dried or ensiled lucerne for equids. (C) 2007 Elsevier B.V. All rights reserved.