Determination of the Lysine Requirement in Segregated Early We

Two growth trials involving 140 weanling pigs were conducted to determine the dietary lysine requirement to maximize growth performance in segregated early-weaned pigs. Pigs were housed in an environmentally controlled off-site nursery. In Experiment 1, 60 pigs (14±2 days of age and 9.3 lb BW) penned in groups of three (5 pens per treatment ) were used to evaluate four dietary lysine levels (1.30, 1.45, 1.60, and 1.75%). In Experiment 2, 80 pigs (14±2 days of age and 9.9 lb BW) penned in groups of four (4 pens per treatment) were used to evaluate five dietary lysine levels (1.30, 1.45, 1.60, 1.75, and 1.90%). Corn starch and sucrose were replaced by whey protein concentrate to increase lysine levels. Lactose content of all diets was 24%. Experimental diets were fed from day 0 to 14 postweaning, and then all pigs were fed a common transition diet (1.40% lysine) from day 14 to 28 and a Phase 2 diet (1.35% lysine) from day 28 to 42. Pigs in Experiment 2 were bled on day 14, 28 and 42 postweaning to determine urea N concentration. In Experiment 1 increasing dietary lysine improved average daily gain and gain:feed from day 0 to 7, and 0 to 14 postweaning linearly, (maximized at 1.75% dietary lysine). In Experiment 2 ADG and gain:feed increased with increasing dietary lysine during day 0 to 7, 0 to 14 and 0 to 42 postweaning. Both response criteria were maximized at 1.90% lysine. Concentration of blood urea nitrogen increased with increased dietary lysine. These results suggest that segregated early weaned pigs require at least 1.75% of total dietary lysine to optimize growth performance during day 0 to 14 postweaning.