Nutrient composition and in vitro ruminal fermentation of tropical legume mixtures with contrasting tannin contents

• Published in: Animal feed science and technology 2007-10, Vol.138 (1), p.29-46
• Main Authors: Stürm, C.D., Tiemann, T.T., Lascano, C.E., Kreuzer, M., Hess, H.D.
• Format: Article
• Language: English
• Subjects: antinutritional factors; Biological and medical sciences; Calliandra calothyrsus; Cratylia; Cratylia argentea; diet; dry season; Feed and pet food industries; Flemingia macrophylla; Food industries; forage legumes; Fundamental and applied biological sciences. Psychology; gas production (biological); in vitro digestibility; Leucaena leucocephala; mixtures; nutrient content; nutritive value; protein supplements; rumen fermentation; Ruminal fermentation; ruminant nutrition; ruminants; shrubs; species differences; Tannin; tannins; tropics
• ISSN: 0377-8401; 1873-2216
• DOI: 10.1016/j.anifeedsci.2006.11.008

Various combinations of a low-tannin herbaceous legume ( Vigna unguiculata) and foliage of tanniniferous shrub legumes ( Calliandra calothyrsus, Flemingia macrophylla and Leucaena leucocephala) or a low-tannin shrub legume ( Cratylia argentea), all mixed together with a low-quality tropical grass ( Brachiaria humidicola), were tested in vitro for differences in the effects on ruminal fermentation. Two experiments with the gas transducer technique were carried out, where each forage mixture was tested either with or without polyethylene glycol in order to be able to identify tannin-related effects ( n = 3). In Experiment 1, a stepwise replacement of V. unguiculata by C. calothyrsus (5:0, 4:1, 3:2, 2:3, 1:4, 0:5) at a legume proportion of 1/3 or 2/3 in the mixture was evaluated. Together with two grass-alone and four pure legume treatments this added up to 30 treatments. In Experiment 2, V. unguiculata was gradually replaced by each of the four shrub legumes (3:0, 2:1, 1:2, 0:3) in grass–legume ratios of 2:1, adding up, together with two grass-alone treatments, to 28 treatments. When added alone, V. unguiculata resulted in high fermentative activity as measured by gas production and kinetics as well as low proportion of undegraded crude protein. When V. unguiculata was replaced by the low-tannin C. argentea in Experiment 2, there was no noticeable difference (P>0.05) in fermentative activity. In both experiments, the effect of the substitution of V. unguiculata by tanniniferous shrub legumes resulted in a declining gas production and an increasing proportion of undegraded crude protein (P