LAUSR

| G5 and G8 are two sorghum mutant lines projected as special sorghum varieties for forage in Indonesia. The objective of this research was to investigate the nutrient profile and in vitro gas production characteristics from two sorghum mutant lines as forage for ruminants. The two mutant lines were compared with Numbu and Pahat variety. Nutients and in vitro digestibility studies were also investigated at different generative phase. This research was arranged into a randomized block design with two factors. The first factor was the variety/mutant lines of sorghum. The second factor was the generative phase (flowering, soft dough and hard dough). Variables measured were nutrients profile, in vitro gas production and rumen fermentation products. Results showed that G5 at hard dough phase produced the highest stem sugar content (P<0.01). The highest potential in vitro gas production (a+b) was found at G5 mutant lines at hard dough stage (P<0.01). Pahat and G5 at hard dough phase had the highest in vitro true digestibility (IVTD) with 54.48 and 54.61% repectively. The highest total volatile fatty acids (TVFA) was found at G5 and G8 mutant lines at hard dough stage (P<0.01). Meanwhile, the best CO2:CH4 ratio was produced by Pahat, G5 and G8 (P<0.01). Based on those findings, it can be concluded that G5 mutant lines had higher quality of nutrients profile, potential in vitro gas production and IVTD. Increasing generative phase also could increase in vitro digestibility for all varieties/ mutant lines.