Milk cholesterol concentration in sows selected for three generations for high or low serum cholesterol

Female crossbred swine (Chester White x Landrace x Large White x Yorkshire) selected for three generations for low (L, n = 24) or high (H, n = 26) serum cholesterol at 8 wk of age were milked at d 20 or 21 of their first lactation to measure cholesterol, fat, lactose, protein, and ash concentrations. A contemporary, unselected control (C) group from the same original population (third lactation, n = 7) was sampled concurrently. All sows were fed a standard gestation, then lactation, diet that contained no cholesterol or added fat (all plant, corn-soybean meal). Genetic selection for low or high serum cholesterol at 8 wk of age induced corresponding changes in milk cholesterol and fat concentration in the third generation of selection, but not in any other milk constituents. Milk cholesterol concentrations (milligrams/100 grams fresh weight) were L, 25.3 +/- 3.0; C, 35.7 +/- 8.0; and H, 41.4 +/- 6.9 (L < C < H, P < .01). Corresponding values for milk fat were 5.7 +/- 1.3, 7.2 +/- .8, and 7.0 +/- .8 mg (L < C = H, P < .01). Serum cholesterol concentrations at 8 wk of age were L, 66.1 +/- 8.1; C, 93.7 +/- 13.7; and H, 126.2 +/- 9.7 mg/dL (P < .01). Milk cholesterol concentration was significantly correlated with serum cholesterol (r = .782, P < .01) and milk fat (r = .36, P < .01). It seems that selecting swine for low or high serum cholesterol at 8 wk of age induced changes in lipid metabolism reflected in differences in milk cholesterol concentrations.