An experiment was conducted to study the effect of feeding expander extruder processed sunflower head (SFH) based complete diets incorporated at 40 and 50% and compared with conventional ration (concentrate mixture to meet protein requirements for maintenance and ad lib sorghum straw). These three rations were fed to fistulated buffaloes in a 3 x 3 Latin square design. A 6d metabolic trial was conducted each time after a preliminary feeding period of 21 days and rumen liquor was collected after each trial for 3 consecutive days, 5 times a day, before feeding (0 h) and at 2 h intervals after feeding (2, 4, 6 and 8 h) to assess nutrient utilization and rumen fermentation pattern. The organic matter, crude protein, ether extract, crude fibre, acid detergent fibre and cellulose (P<0.05) digestibilities were higher (P<0.01) in animals fed either of the complete diets compared to conventional feeding. The buffaloes fed the 40% SFH diet digested higher (P<0.01) dry matter, energy and neutral detergent fibre (P<0.05) compared to the conventional group. The calcium balance was comparable, while phosphorus (P<0.01) and nitrogen (P<0.05) balances were higher on the 40% SFH diet compared to the conventional diet and intermediate on the 50% SFH diet. The ruminal pH was lower (P<0.01), while total volatile fatty acids, total nitrogen and TCA precipitable nitrogen was higher (P<0.01) with the SFH diets than the conventional diet. The ammonia nitrogen was higher in the 40% SFH diet fed animals compared to the other two diets. The results of this study indicated that SFH could form a roughage source for ruminants by incorporating in an expander extruder processed complete diet at either the 40 or 50% level. Out of these two complete diets, the expander extruder processed complete diet containing 40% SFH proved better in terms of nutrient utilization and rumen fermentation pattern.