Dietary Lysine Requirements Of Sgregated Early-Weaned Pigs

Kansas State University Swine Research. A total of 320 (160 barrows and 160 gilts) 14- to 18-d-old pigs (initially 10.2 2.2 lb) was used to determine the optimal level of dietary lysine needed for the segregated earlyweaned pig. Two diet formulation methods were used with six dietary lysine levels within each formulation method, resulting in a 2 6 factorial arrangement of treatments. The first formulation method consisted of a basal diet that contained 1.95% lysine. Increasing levels of cornstarch replaced Llysine to achieve the other five dietary treatments (1.2, 1.35, 1.50, 1.65, and 1.80% dietary lysine). All other amino acids in each diet were maintained at the same level as in the 1.95% lysine treatment. The second formulation method consisted of a basal diet (1.2% lysine) with the five additional treatments achieved by adding synthetic lysine and other essential amino acids to maintain an ideal amino acid ratio, relative to lysine. All diets contained 20% dried whey, 10% lactose, 7.5% spray-dried porcine plasma, 5.0% spray-dried wheat gluten, 5.0% select menhaden fish meal, 5.0% soybean oil, and 1.75% spray-dried blood meal. No lysine formulation method interactions occurred for average daily gain (ADG) or average daily feed intake (ADFI) throughout the 28 d period. However, lysine formulation method interactions were observed for feed efficiency (F/G) from d 0 to 7, d 0 to 14, and d 0 to 28. From d 0 to 7 postweaning, ADG was improved quadratically as dietary lysine increased and appeared to be maximized at 1.65% dietary lysine. Feed efficiency was lowest for pigs fed 1.80% lysine for the first diet formulation method and for pigs fed 1.95% lysine for the second diet formulation method. From d 0 to 14 postweaning, ADG and F/G were improved by increasing dietary lysine, with both response criteria maximized in pigs fed approximately 1.65% dietary lysine. However, ADFI was not affected during the 28-d experiment. These data suggest that segregated early-weaned pigs require approximately 5.2 and 6.2 g/d of lysine from d 0 to 7 and d 0 to 14 postweaning, respectively, to optimize growth performance. Based on these results, the diet for pigs < 11 lb needs to be formulated to contain at least 1.7% lysine. The transition diet (11 to 15 lb) should be formulated to contain approximately 1.5 to 1.6% lysine.