The yield and composition of milk from sows fed on three ration levels

Abstract

Two experiments were conducted in which the effects of three ration levels upon the yield and composition of sows' milk and the efficiency of milk production over the last seven weeks of an eight-week lactation were examined. The levels fed were: 6 units per sow and I unit per piglet suckled; 4 units per sow and ⅔ per piglet; and 3 units per sow and ½ per piglet per day. (A gallon of milk or a pound of concentrate was regarded as one feed unit.) There was a slight reduction in yield per sow and per piglet when the ration was reduced from 6 + 1 to 4 + ⅔, but no reduction when the ration was lowered from 4 + ⅔ to 3 + ½. The average milk yield per sow and per piglet for the 4 treatments were, in the first experiment: 6 + 1, 573 Ib and 86.7 lb; 4 + ⅔, 493 lb and 82.1 lb; and in the second experiment: 4 + ⅔, 668 lb and 78.6 lb ; 3 + ½, 614 1b and 83 lb. The reduction in yield resulting from lowered intake was largely offset by the increased energy content of the milk, the values for the treatments being, for the first experiment: 6 + 1: 619 kcal/lb; 4 + ⅔: 638 kcal/lb; and for the second experiment, 4 + ⅔: 648 kcal/lb; 3 + lh: 653 kcal/lb. The average yield of milk energy per sow and per piglet for the four treatments were, for the first experiment: 6 + 1, 354 and 53.6 therms* One Therm = 1000 kilocalories. View all notes; 4 + 73, 314 and 52.4 therms; and in the second experiment: 4 + ⅔, 433 and 50.9 therms; 3 + ½, 401 and 54.2 therms. There was a pronounced tendency for the fat content of the milk to increase as the ration was lowered and for the lactose content to decrease. The sows on the lower rations used their feed energy equivalent (allowance being made for the energy content of body reserves) more efficiently than those on the higher ration. The values for gross efficiency of milk production for the four treatments were: 6 + 1 : 40%; 4 + ⅔ : 48%; 4 + ⅔ : 48%; and 3 + ½ : 53%. The calculated percentages of the metabolisable sow feed energy equivalent recovered as tissue energy in the litters were: 6 + 1 : 20%; 4 + ⅔ : 24%; 4 + ⅔ : 25%; and 3 + ½: 26%.