Objective: The effect of Phosphorous (P) on lactating cows diet on milk production, reproductive performance and health of the mammary gland in a specialized dairy (SLE) and a double purpose (SDP) system, was determined. Materials and Methods: 48 cows belonging to two different production systems were used (24 animals per system). Cows in each system were randomly assigned to three groups each one receiving mineralized salt with P at 0 %, 4%, and 8% respectively Results: Highly significant differences were found in milk production in SDP between cows consuming salt with P at 8% and 0% , showing with greater production in the group of P at 0%. In SLE an increase in the presence of Streptococcus agalactiae in cows consuming salt with P (at 4% and 0%) was detected. Likewise, the somatic cell count in this farm was lower in cows consuming P at 8% than the ones in the other two groups. The reproductive variables showed no significant effects on any of the two evaluated farms. The economic analysis showed a saving of almost 50% in value of mineral supplement being more efficient the group consuming salt with P at 4% and at 8% without altering the herds' productive performance. Conclusion: For the cases evaluated, the supply of mineralized salt with P at 4% and 8% in dairy cattle did not alter milk production, reproductive performance and mammal gland health in relation to those animals receiving salt without P.