Nutritional Effects and Costs of a Tannin in a Grazing and a Browsing Macropodid Marsupial Herbivore

1. The effect of tannin on herbivores varies depending on the tannin type and level fed, and on the consumer. We measured some nutritional effects of quebracho, a condensed tannin, on two marsupial foregut fermenters, a grazer and a browser. 2. At 6% dietary quebracho, effects on dry matter digestibility, digestible dry matter intake, digestible energy and protein digestibility varied. The effects were greatest in the grazer (Macropus parma) and least in the browser (Thylogale billardierii). These results support the hypothesis that feeding niche correlates with impact of tannin on consumers. 3. A low level of quebracho (3%) did not affect protein digestibility in T. billardierii (M. parma not tested). 4. Faecal tannin recovery was higher in M. parma than in T. billardierii. 5. We could not detect other costs of absorbed quebracho in terms of the conversion of digestible to metabolizable energy, or by excretion of glucuronic acid conjugates.