Animal Feed Science and Technology 123–124 (2005) 277–289 Assessment of tree fodder preference by cattle using chemical composition, in vitro gas production and in situ degradability Carlos A. Sandoval-Castro ∗ , Henry L. Lizarraga-Sanchez, Francisco J. Solorio-Sanchez Facultad de Medicina Veterinaria y Zootecnia, Universidad Aut´ onoma de Yucat´ an, Apdo. 4-116 Itzimn ´ a, M´ erida, Yucat´ an 97100, M´ exico Abstract Short term preference for five tree fodders by cattle was assessed by their chemical composition, as well as in situ and in vitro gas production, in two studies. In study 1, five heifers (341 ± 36 kg liveweight) were offered Brosimun alicastrun (BA), Piscidia piscipula (PP), Leucaena leucocephala (LL), Lysiloma latisiliquum (TL) and Guazuma ulmifolia (GU) in a 6 h ‘cafeteria’ study over 5 consecutive days. In study 2, the same 5 heifers and tree fodders were used, but each heifer was offered a single tree fodder and fresh Taiwan grass (Pennisetum purpureum) ad libitum for 6 h. After 6 h, refusals were weighed and, for the rest of the day, only Taiwan grass was offered ad libitum. Forages offered in both studies were analyzed for dry matter (DM), crude protein, ash, neutral detergent fibre, acid detergent fibre, lignin, total polyphenols and condensed tannins, as well as for in situ DM degradation (0, 3, 6, 12, 24, 48, 72 and 96 h) and in vitro gas production (3, 6, 9, 12, 15, 18, 21, 24, 30, 36, 48, 60, 72, 96 and 120 h). In situ degradability was fitted to the equation p = a + b(1-e -ct ), while the equation gas = GV(1 + (B/t) C-1 ) was used for in vitro gas production. Residues from in vitro gas production were used to estimate in vitro DM and organic matter digestibility. Relationship between tree fodder intake, chemical composition, and in situ and in vitro digestibility was assessed using Pearson correlation analysis. In study 1, tree fodder intake (g DM/kg LW 0.75 ) was: PP 5.41, TL 5.62, LL 15.62, GU 17.31 and BA 55.36 (S.E.D. 1.63). Intake was correlated with lignin (Pearson coefficient, -0.898, Abbreviations: ADF, acid detergent fibre; C, condensed tannins; TP, total phenols; DM, dry matter; DMI, DM intake; IVOMD, in vitro apparent DM digestibility; IVOMD, in vitro apparent OM digestibility; IVGP, in vitro gas production; NDF, neutral detergent fibre; OM, organic matter ∗ Corresponding author. Fax: +52 999 9 42 32 05. E-mail address: ccastro@tunku.uady.mx (C.A. Sandoval-Castro). 0377-8401/$ – see front matter © 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.anifeedsci.2005.04.057