Dietary Magnesium Levels for Sows during Gestation and Lactation

Thirty-six crossbred gilts 10 months of age were bred and assigned to dietary magnesium levels of 400 or 900 ppm. At parturition the levels were modified to 150 and 650 ppm. During lactation phosphorus levels of .30 or .54% were fed within each magnesium level. Magnesium levels did not influence the number or weight of pigs at birth or weaning. Sows fed the high level of magnesium (650 ppm) maintained equilibrium in magnesium balance (corrected for losses in feces, urine and milk) while sows on low magnesium evidenced a severe negative balance. The sows were in negative balance on most treatments for calcium, phosphorus and potassium. The magnesium in serum, ribs and turbinates was lower after a 36-day lactation in sows fed the low level of magnesium.