RESPONSE OF PIGS TO SPACE ALLOCATION AND DIETS VARYING IN NUTRIENT DENSITY

Three experiments were conducted to determine the main and interacting effects on growth performance of Floor space allowance and dietary ly sine and energy concentrations for growing-finishing pigs. In each exp eriment, space allocations of .56 or .78 m(2)/pig were achieved with 1 4 or 10 pigs per pen, respectively. In Exp. 1, diets investigated were National Research Council (NRC) recommended nutrient densities, NRC p lus 5% added fat (F), NRC plus .15% added L-lysine HCl (L), and NRC pl us fat plus lysine (FL) in a 4 x 2 x 2 factorial arrangement of diets with space and season (winter vs summer). In Exp. 2 and 3, a 2 x 3 fac torial treatment arrangement was used to investigate space and diet ef fects. Diets investigated contained 0, 2.5, or 5% added fat (choice wh ite grease [Exp. 2]; tallow [Exp, 3]) with L-lysine . HCl added to mai ntain a constant lysine:ME ratio. In Exp. 1, pigs given .56 m(2)/pig v s .78 m(2)/pig ate less feed (P < .001) and grew slower (P < .001) wit h no difference in gain:feed ratio or carcass lean percentage. Feed in take was decreased (P < .005) and gain:feed ratio increased (P < .001) for the FL vs L diet. In Exp. 2, pigs given .56 m(2)/pig vs .78 m(2)/ pig grew slower (P < .001) with a poorer gain:feed ratio (P < .05) and a slower rate of lean gain (P < .05). In Exp. 3, pigs given .56 m(2)/ pig vs .18 m(2)/pig grew slower (P < .05) with no difference in gain:f eed ratio and a slower rate of lean gain (P < .005). There was a linea r improvement in ADG (P < .01, Exp. 2; P = .011, Exp. 3) and gain:feed ratio (P < .001, Exp. 2 and 3) with increasing amounts of fat in the diet. The lack of space x diet interactions in these experiments sugge sts that the reduction in ADG associated with the reduction in ADFI fo r pigs given less space is independent of dietary lysine and energy co ncentrations.