SOURCES OF VARIATION IN NUTRITIVE VALUES OF TROPICAL FORAGES FROM THECARIBBEAN

The chemical composition, in vitro digestibility with rumen liquor and agricultural factors (age of regrowth, season, level of fertilization ) of 1313 tropical forages from various islands of the Caribbean and o f La Reunion were recorded in a database. The nutritive values were ex pressed in the French unit system, i.e. digestible energy, metabolizab le energy, net energy for lactation, net energy for maintenance and gr owth, protein digestible in the small intestine supplied by rumen-unde graded dietary protein (PDIA), protein digestible in the small intesti ne supplied by microbial protein from numen-fermented organic matter ( PDIME), protein digestible in the small intestine supplied by microbia l protein from rumen-degraded dietary protein (PDIMN), and voluntary d ry matter (DM) intake by sheep (VDMIs), dairy cows or growing cattle. Digestibility of DM and OM and voluntary DM intake were determined wit h regression equations fitted to tropical data previously reported. Th e age of regrowth and the type of forage were the main sources of vari ation, whereas the country, season and level of nitrogen fertilization had no important effect on energy or protein values. Mean nutritive v alues are given for each type of forage and age of regrowth after corr ection for the level of nitrogen fertilization, season and country.