Linear regression equations were developed to directly calculate nutrient requirements for dairy cattle (TDN, DE, ME, NEL, CP, Ca, P, Vitamin A, and Vitamin D) across three physiological stages: maintenance, pregnancy, and milk production, based on the National Research Council (NRC) nutrient requirements tables. The equations were derived using the animal's live weight (400–800 kg) and milk fat percentage (3.0–5.5%) as independent variables. The R-squared values for all equations were above 0.99, indicating a high degree of accuracy. For maintenance requirements, the equations were: - TND (kg) = 1.0273 + 0.0053 × PV - ED (Mcal) = 4.5356 + 0.0235 × PV - EM (Mcal) = 3.9389 + 0.0205 × PV - NEL (Mcal) = 2.3578 + 0.0122 × PV - CP (g) = 152.11 + 0.4217 × PV For pregnant cows in the last two months of gestation, the equations were: - TND (kg) = 1.3578 + 0.00707 × PV - ED (Mcal) = 5.9896 + 0.031 × PV - EM (Mcal) = 5.0169 + 0.0260 × PV - NEL (Mcal) = 2.958 + 0.0161 × PV - CP (g) = 292.76 + 1.5147 × PV For milk production, the equations were: - TND (kg) = 0.1539 + 0.042 × %G - ED (Mcal) = 0.6701 + 0.1874 × %G - EM (Mcal) = 0.5772 + 0.1646 × %G - NEL (Mcal) = 0.3569 + 0.0949 × %G - CP (g) = 43.610 + 11.543 × %G Mineral and vitamin equations were also derived, with high R-squared values. These equations allow for accurate estimation of nutrient requirements for dairy cattle in different stages, facilitating individualized feeding calculations. The results show that the regression equations provide a reliable method for determining nutrient needs, improving efficiency and accuracy in dairy cattle nutritionLinear regression equations were developed to directly calculate nutrient requirements for dairy cattle (TDN, DE, ME, NEL, CP, Ca, P, Vitamin A, and Vitamin D) across three physiological stages: maintenance, pregnancy, and milk production, based on the National Research Council (NRC) nutrient requirements tables. The equations were derived using the animal's live weight (400–800 kg) and milk fat percentage (3.0–5.5%) as independent variables. The R-squared values for all equations were above 0.99, indicating a high degree of accuracy. For maintenance requirements, the equations were: - TND (kg) = 1.0273 + 0.0053 × PV - ED (Mcal) = 4.5356 + 0.0235 × PV - EM (Mcal) = 3.9389 + 0.0205 × PV - NEL (Mcal) = 2.3578 + 0.0122 × PV - CP (g) = 152.11 + 0.4217 × PV For pregnant cows in the last two months of gestation, the equations were: - TND (kg) = 1.3578 + 0.00707 × PV - ED (Mcal) = 5.9896 + 0.031 × PV - EM (Mcal) = 5.0169 + 0.0260 × PV - NEL (Mcal) = 2.958 + 0.0161 × PV - CP (g) = 292.76 + 1.5147 × PV For milk production, the equations were: - TND (kg) = 0.1539 + 0.042 × %G - ED (Mcal) = 0.6701 + 0.1874 × %G - EM (Mcal) = 0.5772 + 0.1646 × %G - NEL (Mcal) = 0.3569 + 0.0949 × %G - CP (g) = 43.610 + 11.543 × %G Mineral and vitamin equations were also derived, with high R-squared values. These equations allow for accurate estimation of nutrient requirements for dairy cattle in different stages, facilitating individualized feeding calculations. The results show that the regression equations provide a reliable method for determining nutrient needs, improving efficiency and accuracy in dairy cattle nutrition