SEASONAL-VARIATION OF SELENIUM, CRUDE PROTEIN, AND IN-VITRO ORGANIC-MATTER DIGESTIBILITY OF BRACHIARIA-HUMIDICOLA FROM MARAJO ISLAND, BRAZIL

Nutritional content of Brachiaria humidicola grass in relation to crud e protein (CP), in vitro organic matter digestibility (IVOMD), and sel enium (Se) as related to wet and dry seasons in the Amazon region of M arajo Island, Brazil, was determined. Twenty-four samples, 12 from the dry and 12 from the wet season, were analyzed. Grass selenium concent rations were not influenced by season and the means were above the min imal requirement for beef cattle in both seasons (0.14 or 0.15 ppm). F actors other than rainfall may be involved. Crude protein concentratio ns were lower (P < 0.05) in the dry (3.5%) than in the rainy season (4 .8%) and in both seasons were lower than the critical level for cattle (<7.0%). The IVOMD means were extremely low, 33.5% in the wet season and 33.6% in the dry season. These analytical values indicate that Bra chiaria humidicola grown at Marajo Island has nutritional limitations for grazing buffalo and cattle production.