The Relationship between Ruminal Macro Mineral Solubility and Fermentability of Selected Tropical Legumes Tree with Mineral Absorption on Local Sheep

Abstract

A research to study relationship between macromineral solubility, fermentability of some tree legumes with in vivo digestibility using local sheep has been conducted. In the first experiment, five tropical legume trees such as Pterocarpus indicus (PI), Sesbania gradiflora (SG), Gliricidia sepium (GS), Callyandra callotyrsus (CC) and Leucaena leucocephala (LL) were used. A modified in vitro technique was used to determine degradation, fermentation and macromineral bioavailability of selected legume trees. The gas production was measured using Hohenheim method. The ruminal DM degradation and the cumulative gas productions were calculated using a model of Y = a + b (1-e-ct) following method of Ærskov and McDonald (1979). The second experiment aimed to evaluate macro mineral abroption of the legumes. The in vivo digestibility was measured using eighteen male local sheep. The animals were divided into 6 groups with 3 replications (A = native grass as a control, B = Ration A + 20% PI, C = Ration A + 20% SG, D = Ration A + 20% GS, E = Ration A + 20% LL and F = Ration A + 20% CC). The results showed that biodegradation and cummulative gas production of selected legume trees were not significantly different. However, the gas production rate of SG and GS were significantly higher. No difference was observed on VFA production of the legumes, while the NH3 production was different. Legume SG produced more NH3 than other tree legumes. In general, the ruminal Ca solubility was higher than P and Mg. The solubility of Ca and Mg of legume LL were higher than other legumes, while the solubility of P from legume LL was the highest. The in vivo experiment showed that digestibility of the ration containing 20% of tropical legume trees was no difference. However, the DM and OM consumption of ration were significantly different. The DM and OM consumption of ration D was higher (398 and 347 kg head -1day-1) than other rations. The absorption of mineral Ca and P from ration E was higher than other legumes.