The aims of this study were to investigate the effects of different levels of stylo CIAT 184 hay in the dietary rations of fattening cattle on feed intake, feed digestibility, and daily weight gain (ADG) of fattening Sindhi x Local yellow cattle. In this study, 20 Sindhi x Local yellow cattle bulls were at 18 months age with an initial body weight (BW) of 180 + or - 15 kg were used in the RCBD with 4 replications to allocate 5 treatments (KPCS 0, KPCS 25, KPCS 50, KPCS 75 and KPCS 100) corresponded to five levels of stylo hay at 0, 25, 50, 75 and 100 percent of total dry matter in the diets respectively. The total (DM) feed offered was equal to 3 percent of initial body weight (BW) and experimental time was 12 weeks. It was observed that total DM feed intake was significant different among treatments P0.05 (5.33, 6.30, 6.20, 5.73 and 5.50 kg/head/day for KPCS 0, KPCS 25, KPCS 50, KPCS 75 and KPCS 100, respectively). Digestibility of DM was 68.08, 78.03, 77.15, 19.47 and 76.66 for KPCS 0, KPCS 25, KPCS 75 and KPCS 100, respectively. The ADG of animals were in the range of 504 to 676 g/head/day
and the highest ADG was obtained in animal fed with KPCS50 leading to FCR of DM (9.12 kg DM/kg BW gain) and better profit (19.960 VND/head/day). Base on results of this study it could be concluded that can replace 50 percent natural grass by stylo CIAT 184 hay in the diet for fattening Sindhi x Local yellow cattle fed with rice straw and rice bran as a basal diet.