Animal Feed Science and Technology 151 (2009) 65–74 Contents lists available at ScienceDirect Animal Feed Science and Technology journal homepage: www.elsevier.com/locate/anifeedsci In vitro ruminal fermentation of Pennisetum purpureum CT-115 supplemented with four tropical browse legume species R. Rodríguez b , M. Fondevila a,∗ , C. Castrillo a a Departamento de Producción Animal y Ciencia de los Alimentos, Universidad de Zaragoza, Miguel Servet 177, 50013 Zaragoza, Spain b Instituto de Ciencia Animal, Ctra. Central Km 47, Aptdo. 24, San José de Las Lajas, La Habana, Cuba article info Article history: Received 2 April 2008 Received in revised form 19 November 2008 Accepted 19 November 2008 Keywords: Pennisetum purpureum Tropical legumes In vitro gas production abstract An in vitro gas production experiment was completed to deter- mine effects of four tropical browse legumes (i.e., Acacia cornigera, AC; Albizia lebbekoides, AL; Enterolobium cyclocarpum, EC; Leucaena leucocephala, LL)at 0.15 or 0.30 of total substrate on microbial fer- mentation of the tropical grass Pennisetum purpureum CT-115 (PP). Two incubation runs with four bottles per treatment were com- pleted, using two bottles for gas production measurements up to 96 h and two bottles for microbial purine bases (PB) concentration analysis after 24 h. Inclusion of AC, EC and LL linearly increased (P<0.05) gas production from PP alone at an initial stage of fer- mentation (5 h) because of their higher fermentation rate versus PP. However, whereas the linear increase in gas production was maintained at mid fermentation (i.e., 24h) with AC, there was no effect with LL and a linear reduction in gas volume at 24 and 96 h with EC, possibly because of its saponin content. Gas production with AL was linearly reduced at 24 and 96 h (P<0.01). There were no differences in microbial concentrations, either estimated from a partitioning factor or PB analysis, but PB concentration in the solid residue increased three-fold when LL were included. Differences among legume species in chemical composition, and in the nature of their secondary compounds, are responsible for the fermentation pattern of mixed substrates. © 2008 Elsevier B.V. All rights reserved. Abbreviations: AC, Acacia cornigera; AL, Albizia lebbekoides; ADFom, acid detergent fibre exclusive of residual ash; NDFom, neutral detergent fibre exclusive of residual ash; CT, condensed tannins; DM, dry matter; EC, Enterolobium cyclocarpum; LL, Leucaena leucocephala; OM, organic matter; OMD, OM apparent digestibility; PB, purine bases; PEG, polyethylene glycol; PF, partitioning factor; PP, Pennisetum purpureum. ∗ Corresponding author. Tel.: +34 976 761660; fax: +34 976 761590. E-mail address: mfonde@unizar.es (M. Fondevila). 0377-8401/$ – see front matter © 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.anifeedsci.2008.11.005