A study was conducted using 20 Bunaji bulls with a live weight range of 210-249kg, and age range of 2-3 years to evaluate the feeding value of raw or parboiled rice offal as energy source for bull fattening. Four bulls per treatment were allotted to five dietary treatments in a 2x2 factorial arrangement with a common control. Feeding and metabolism trials were conducted for 90 and 21 days, respectively. Rumen fluid was collected at 0, 2, 4 and 6hrs intervals to determine the rumen pH, rumen ammonia nitrogen and rumen total volatile fatty acid for all the bulls. A concentrate and basal diets of Digitaria smutsii were offered at 2% body weight. The proximate and mineral composition of the feed ingredients showed that raw rice offal (RRO) had 7.69% CP, 6.64% hemicellulose and 24.86% silica while parboiled rice offal had (PRO) 4.38% CP, 6.10% hemicellulose and 36.91% silica. In terms of mineral contents, RRO was only higher in magnesium. The CP contents of the experimental diets vary between 19.69 and 20.44% while the ME ranged from 10.86 to 11.16MJ/kg DM. The crude fibre varies from 14.59 to 17.84%. The result of the fattening trial showed that there was no significant (P>0.05) difference in concentrate, hay, total dry matter intakes and daily weight gain of bulls fed the control diet (NRO) and diets containing RRO and PRO. Inclusion level of rice offal had no significant effect (P>0.05) on intake of concentrate, hay and total feed intake. However, live weight gain of the bulls on the control diet was significantly (P<0.05) higher than bulls on 20 and 30% rice offal inclusion The intake of concentrate, hay, total feed and daily live weight gain of the bulls were similar (P>0.05) irrespective of type and inclusion levels of the rice offal. All the bulls experimented attained an average weight gain of between 1.11Kg to 1.29Kg which was above 1Kg. Rumen parameters were not significantly (P>0.05) affected by rice type but significantly (P<0.05) affected by inclusion level. The result showed that Rumen pH at 6hrs after feeding at 0% (6.63) and 30% (6.76) were similar (P>0.05), but differed (P<0.05) significantly from 20% (6.93) inclusion level. Total Volatile Fatty Acid (TVFA) was not significant at 0hr before feeding with 0% being similar to 20 and 30% inclusion levels. Bulls on diet containing 20% inclusion levels had the highest TVFA value (44.70 μmol) with the least (23.49 μmol.) being those on 30%. Varying the levels of inclusion of RRO and PRO was not significant (P>0.05) on rumen pH and TVFA at different sampling time. However, significant (P<0.05) difference was observed for Rumen Ammonia Nitrogen (RAN) at 2hrs post feeding. Bulls on 30% PRO had the highest value (22.41g/100g) while 20% PRO (14.80g/100g) had the least value. The result of the carcass evaluation showed significant (P<0.05) difference with rice type for legs, spleen, Empty stomach, Empty intestine, inguinal fat, abdominal fat with PRO being higher except for the spleen which is higher for RRO. At varying levels of inclusion of rice offal, there was significant (P<0.05) difference in dressing percentage, Beef percent of carcass, meat to bone ratio, legs, hide, tail, empty stomach, stomach with content, empty intestine, Inguinal fat, kidney fat, abdominal fat, depth of chest fat, testis and blood. Carcass evaluation for bulls on diets with varying levels of inclusion of raw or parboiled rice offal were significant (P< 0.05) for legs, hide, empty stomach, empty intestine, inguinal fat and abdominal fat. Economic parameters such as cost per Kg gain, net benefit (NB) and return to naira invested on feed (RIF) were similar (P>0.05) for bulls on both RRO and PRO. Daily weight gain was significantly (P<0.05) affected by inclusion level with bulls on the control diet 0% having the highest(1.29Kg) while those on 20% (1.15 Kg) and 30% (1.14 Kg) were statistically (P>0.05) similar. Value of gain was significant (P<0.05) but decrease with increase in inclusion level. There was no significant (P>0.05) differences in the Value of weight gain (VWG), NB, RIF, Cost of feed and Cost per Kg gain for bulls on varying levels of inclusion of RRO or PRO. The inclusion of raw rice offal or parboiled rice offal lead to reduction in feed cost from N25,001.10 to a range of N22,115.50- N23,639.6 (about 5.45%-11.54% reduction in feed cost). It was therefore concluded from this trial that the meat from bulls fed 30% rice offal, (either raw or parboiled) were of better quality due to low fat. Similarly, rice offal of all kind (raw or parboiled) may be used to replace up to 30% of maize offal as source of energy in the diets of fattened Bunaji bulls without any detrimental effect on live weight. Hence it can be adopted by farmers