Abstract

Three experiments were conducted to determine the main and interacting effects on growth performance of floor space allowance and dietary lysine and energy concentrations for growing-finishing pigs. In each experiment, space allocations of .56 or .78 m2/pig were achieved with 14 or 10 pigs per pen, respectively. In Exp. 1, diets investigated were National Research Council (NRC) recommended nutrient densities, NRC plus 5% added fat (F), NRC plus .15% added L-lysine. HCl (L), and NRC plus fat plus lysine (FL) in a 4 × 2 × 2 factorial arrangement of diets with space and season (winter vs summer). In Exp. 2 and 3, a 2 × 3 factorial treatment arrangement was used to investigate space and diet effects. Diets investigated contained 0, 2.5, or 5% added fat (choice white grease [Exp. 2]; tallow [Exp. 3]) with L-lysine.HCl added to maintain a constant lysine:ME ratio. In Exp.1, pigs given .56 m2/pig vs .78 m2/pig ate less feed (P < .001) and grew slower (P < .001) with no difference in gain:feed ratio or carcass lean percentage. Feed intake was decreased (P < .005) and gain:feed ratio increased (P < .001) for the FL vs L diet. In Exp. 2, pigs given .56 m2/pig vs .78 m2/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 m2/pig vs .78 m2/pig grew slower (P < .05) with no difference in gain:feed ratio and a slower rate of lean gain (P < .005). There was a linear 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 × diet interactions in these experiments suggests that the reduction in ADG associated with the reduction in ADFI for pigs given less space is independent of dietary lysine and energy concentrations.

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