Effect of different protein sources with the same proportion of crud protein (CP) in the TMR diets were investigated on lactating buffalo's performance; nutrients digestibility, milk yield, milk urea nitrogen and economic parameters of production. In the study lactating multiparous Egyptian buffalos were used from 56 to 196 days postpartum. Four isontrogenous diets were applied differing in the main protein sources as follows: ration one R1 (control) containing soybean meal R2: soybean meal (SBM) 50% + cotton seed meal (CSM) 50%, R3: soybean meal 50% + sunflower meal 50%, R4: soybean meal 50 %+ sunflower meal (SFM) 25% + cotton seed meal 25%. Results showed that dry matter and organic matter digestibility was significantly higher in the buffalos fed the R1, compared to R3 diet. No significant differences were found in crude protein digestibility among experimental diets. Daily milk and fat corrected milk yield production of buffalos fed R2 diet were significantly higher compared to the other diets. Milk urea nitrogen concentrations in the milk was found significantly lower in R4 compared with R1 group, which later recorded the highest value (13.0%) among the treatments. It could be concluded that feeding different protein sources may have different effects on milk production, milk composition including urea N and economic parameters of lactating buffalos.