Utilization of stylo (Stylosanthes guianensis (Aubl.) Sev.) with or without flemingia (Flemingia macrophylla Willd. O. Ktze.) and polyethylene glycol as supplement to rice straw-based ration for sheep (Ovis aries)

Four experiments were conducted to enhance the utilization of stylosanthes guianensis (Stylo-CIAT 184) as protein source in rice straw-based ration for sheep. In Experiment 1.1, the freeze-dried stylo leaves had the highest DM [dry matter] and CP [crude protein] contents. Both freeze-dried and sun-dried leaves + stem had the highest NDF [neutral detergent fiber], while freeze-dried leaves + stem had the highest ADF [acid detergent fiber] and cellulose values. Lignin content was highest in freeze-dried and sun-dried leaves + stem. Freeze-dried leaves + stem had the highest N solubility. Sun-drying increased the ADIN [acid detergent insoluble nitrogen] of stylo leaves and leaves + stem. Sun-dried leaves had the highest IVDMD [in vitro dry matter digestibility] after 48 h of rumen incubation. After 72 hr of rumen incubation, both freeze-dried and sun-dried leaves had the highest IVDMD value. Experiment 1.2 showed that increasing levels of stylo supplementation improved the CP and decreased the cell wall components of rice-straw-based rations. The ADIN value was further increased by the inclusion of 20 percent Flemingia with or without PEG [polyethylene glycol]. The N solubility, IVDMD and IVOMD [in vitro organic matter digestibility] values were increased by high level of Stylo suplementation, lowered by the inclusion of 20 percent Flemingia and improved by the addition of PEG. In sacco evaluation (Experiment 2) revealed no significant differences in percent DM and rate of DM disappearance among treatment rations, while percent CP and rate of CP disappearance were significantly lowered by the inclusion of 10 percent Flemingia with or without PEG. In vivo experiment (Experiment 3) indicated that 40 percent Stylo supplementation significantly improved CP digestibility of the ration. In Experiment 4, the evaluation of production responses using 18 growing male sheep showed that sheep in T1 ration had significantly higher total DMI [dry matter intake] (402.54 g/d) and liveweight change (1.79 kg) than those sheep fed rations T2 (385.85 g/d and 1.07 kg) and T3 (388 g/d and 1.22 kg). Supplementation of mixture of Stylo + Flemingia (T3) resulted in ADG and FE similar to that of concentrate supplementation (T1) indicating improvement in N utilization as shown in the insignificant differences in CPI [crude protein intake] N balance and N utilization among treatments. Supplementations of Stylo alone and the mixture of Stylo + Flemingia lowered the total feed cost and feed costs/kg gain per day. The results of the study indicate that the utilization of Stylo as protein source in rice straw-based ration can be enhanced through mixture with tannin-containing legume, which apparently provided the animals with additional by-pass proteins required for high productivity