Contribución ecológica de los taninos de especies leñosas sobre la utilización de nitrógeno por bovinos

This study was conducted on CATIE's experimental farm in Turrialba, Costa Rica to determine the effect of feeding forages of contrasting tannin concentrations on N utilisation by young bulls. The treatments were different supplements of C. calothyrsus and Gliricidia sepium (0: 100, 33: 67, 67: 33 and 100: 0), where increasing levels of C. calothyrsus simulated increasing tannin levels. C. calothyrsus had lower in vitro DM digestibility (30.2 vs 62.1 percent) and higher condensed tannins (18.5 vs 1.8 g kg DM exponente -1) than C. sepium. As the level of C. calothyrsus increased, N intake decreased, faecal N increased, urinary N, N retained and N absorbed decreased whereas the efficiency of use of absorbed N increased. The use of a mixture of forages with contrasting tannin concentrations contributed to increased efficiency of absorbed N and modified pathways of N excretion in ruminants.