Ruminal Solubility of Trace Elements from Selected Philippine Forages

The ruminal solubility of copper (Cu), manganese (Mn), molybdenum (Mo), and zinc (Zn) in eight Philippine forages was studied. These forages were: 1) grasses: paragrass (Brachiaria mutica (Forsk.) Stapf), stargrass (Cynodon plectostachyum Pilger), and napiergrass (Pennisetum purpureum Schumach.); 2) creeping legumes: calopogonium or calopo (Calopogonium muconoides Desv.) and centrocema (Centrocema pubescens Benth.); 3) tree lequmes: gliricidia or kakawate (Gliricidia sepium (Jacq.) Walp.), leucaena or ipil-ipil (Leucaena leucocephala (Lam.) de Wit.), and sesbania or katuray (Sesbania grandiflora (L.) Poir). Nylon bags with samples were incubated for 0, 3, 6, 12, 24, 48 and 72h in three rumen cannulated sheep fed with timothy hay (Phleum pratense L.) at 2% body weight/d. The 0-h bags were washed with deionized water. There were species differences (p < 0.05) on the different solubilities of trace elements. At O-h incubation, the trend of solubility was Mo (54%) > Zn (43%) > Cu (38.7%) > Mn (29.5%). At 3-h incubation, all the elements except Mn had an average solubility above 50%. Combining particulate passage rate (1.9%/h) and various trace elements disappearance rates, the effective ruminal solubilization (ERS) of trace elements were computed. The ERS across species ranged from 44.6 to 89.9% for Cu, 29.9 to 84% for Mn, 66 to 95.1% for Mo, and 30.1 to 82.3% for Zn resulting to a trend of Mo > Zn > Cu > Mn.