A total of 192 pigs were utilized in a 2×3×3 factorial arrangement with an additional control treatment. The treatments were: (1) magnesium level (1.6 vs. 3.2 g of magnesium pig(-1) day(-1)); (2) magnesium source (sulfate vs. proprionate vs. proteinate); (3) feeding duration (5 vs. 2 vs. 1 day), and a control (no supplementary magnesium). Minolta L(∗) values were lower (P⩽0.05), indicating darker muscle color, for pigs supplemented with 1.6 g magnesium pig(-1) day(-1) compared to the controls while pigs on the 3.2 g magnesium level were intermediate between these two treatments. Animals on the 1 day treatment had a higher (P⩽0.05) ultimate pH and lower (P⩽0.05) Minolta L(∗) compared to those on the 2 days and control treatments, while 5 days pigs were intermediate and had lower L(∗) values compared to the controls. The sulfate and proteinate treatments produced pork with the lower (P⩽0.05) Minolta L(∗) values compared to the controls. Pigs fed the sulfate diet had a lower (P⩽0.05) drip loss compared to those on the control treatment. Results from this study suggest that the lowest level (1.6 g magnesium pig(-1) day(-1)) and the shortest time of supplementation (1 day) may be effective in improving pork color and water-holding capacity.