Ingestibilité et digestibilité chez le mouton des foins de cinq graminées tropicales

Five tropical grass hays, two perennial ( Andropogon gayanus Kunth. and Panicum anabaptistum Steud.) and three annual ( Pennisetum pedicellatum Trin., Brachiaria lata Schum. and Andropogon pseudapricus Stapf.) were used at various phenological stages occurring between tillering and the straw stage. Depending on the species and phenological stage, voluntary intake amounts of dry matter (DM) of 23 grass hays by Djallonke (= West African Dwarf) sheep varied from 108 to 26 g/kg of metabolic weight. Total crude protein contents (TCP) of these hays were low (131 to 8 g/kg DM). Digestible crude protein (DCP) contents of the hay rations, given alone or protein-supplemented (with cottonseed cake, legume haulms) were positively and closely related (r = 0.996; residual standard error (RSE) = 2.61; n = 36) to ingested TCP contents. Decrease of organic matter digestibility (OMd) during the cycle (0.21 point/day) induced an intake decrease of 1.6 g DM per kilogram of metabolic weight and per OMd point. OMd was highly correlated to the non-digested wall contents (NDFnd) of the hays (r = 0.979; RSE = 2.15; n = 23), and S the soluble fraction (1000 - NDF) had a true digestibility of about 100%.