Effect of energy intake on performance, carcass merit and energy utilization of growing-finishing swine

Typescript (photocopy).A serial slaughter study was used to evaluate the effect of four energy intake levels, (1) ad libitum (ad lib); (2) 85% ad lib (85%); (3) 70% ad lib (70%); or, (4) Danish scale feeding system (DS), on performance, carcass merit and energy utilization from 20 to 110 kg live weight. A concurrent study evaluated the use of deuterium oxide as a predictor of body composition. Eight pigs were slaughtered when the test began at 20 kg. Four pigs per treatment were subsequently slaughtered at live weights of 50, 80, 95 and 110 kg for carcass measurements and chemical analyses. Pigs were infused with deuterium oxide (D(,2)O, .25 g/kg body weight) 3d prior to slaughter. Blood samples were collected at 0, 10, 20, 30, 40 and 80 min, 5, 24, 48 and 72 h post infusion. Ad lib pigs received a 16% protein corn-soybean meal diet from 20 to 50 kg and a 14% thereafter. The 85 and 70% diets contained 15 and 30% more protein, minerals and vitamins than ad lib diets. Feed intake for these treatments were calculated from the consumption of ad lib-fed pigs at comparable live weights. Danish system pigs received the recommended daily requirement of energy, lysine and minerals specified in Danish feed tables for each 10 kg weight interval from 20 to 110 kg. Restricting energy intake from ad lib to 70% decreased average daily gain (ADG) linearly (P > .01) similar to the degree of energy restriction (848, 745 and 586 g/day for ad lib, 85 and 70% groups) over the 20 to 110 kg weight range. Average age at 110 kg for the 85 and 70% groups were 14 and 46 d more than the ad lib group. Gain:feed ratio (G/F) measured over the entire trial was 5% more desirable for the 85% than the ad lib-fed pigs (.295 vs .281); G/F was least desirable for the 70% group (.275). ..