A study was conducted to determine the effect of supplementation of calcium (Ca) and phosphorus (P) on nutrient utilization, milk production, its composition and reproductive performance of Nili-Ravi buffaloes. Twelve lactating buffaloes were randomly divided into three groups, with 4 animals in each group, fed diets containing 80, 100 and 120% NRC recommended Ca and P, respectively. Daily feed consumption and milk yield (MY) were recorded. Fortnightly collected milk samples were analyzed for total solids (TS), milk protein (MP), milk fat (MF), lactose, Ca and P contents. Calcium and P concentrations were also determined in blood serum. Milk yield was 10%, MF 4% and TS 3.7% higher in buffaloes fed on 120% Ca and P than those fed on 100% Ca and P of NRC recommendation but dry matter intake was similar among all groups. However, MP, lactose and solids not fat were not affected by mineral supplementation. In milk, slightly increased concentrations of Ca and P were noted during the last two weeks of experiment in all groups. Dietary protein digestibility was higher in buffaloes fed 120% Ca and P, crude fibre and dry matter digestibility was higher in 80 and 100% Ca and P supplemented groups respectively however, difference was non-significant among the groups. Serum P concentration was higher but Ca was lower in 120% Ca and P supplemented group compared to other two groups however, these values were within the normal range. Buffaloes fed 120% Ca and P conceived 100% but in buffaloes fed 100 and 80% Ca and P, conception rates were 75 and 50% respectively. Number of services per conception was lower in buffaloes fed 120% Ca and P supplemented diet. It may be concluded that 120% Ca and P supplementation increased milk production and reproductive performance of lactating buffaloes.

Key words: Buffaloes, Milk composition, Reproduction, Calcium, Phosphorus, Supplementation