Feeding trials using slow ammonia release and protected protein supplement (SARPP) were conducted on lactating crossbred cows (n=24) and buffaloes (n=24). Animals were divided into three groups of eight each, based on milk yield, fat percentage and stage of lactation. In addition to basal ration, animals in groups I, II and III were fed 1.0 kg untreated rapeseed meal containing 50 g untreated urea, 1.0 kg treated meal containing 50 g untreated urea and 1.0 kg treated meal containing 50 g treated urea, respectively. In cows, the level of blood urea-N (mg/dl) was 12.23, 12.29 and 11.63, whereas, level of allantoins (mmol/litre) in urine was 7.94, 9.31 and 13.85 in groups I, II and III, respectively. The average milk yield (kg) and fat (%) in three groups of cows were 9.67 & 4.30, 10.61 & 4.56 and 11.05 & 4.58, respectively. In buffaloes, the level of blood urea nitrogen (mg/dl) was 10.33, 10.48 and 9.64 and the level of allantoins (mmol/litre) in urine was 2.35, 3.03 and 5.23 in groups I, II and III respectively. The average milk yield (kg) and fat (%) in three groups of buffaloes were 6.46 & 6.64, 7.42 & 6.81 and 7.70 & 6.86, respectively. The present study suggested that SARPP is promising feed supplement for increasing milk yield in cows and buffaloes.