Effects of Lysine (and ideal protein) Levels on Performance of Pigs with and without the Addition of a Blend of Phytonutrients (Lean Fuel) in the Late Finishing Phase

The objective of this experiment was to determine whether the response in performance to different levels of lysine (ideal protein) is affected by a blend of phytonutrients (Lean Fuel, LF), and whether altered Lysine:ME ratios are required when formulating with LF. A total of 1,847 DNA 600 finishing pigs (BW=85.7kg, 2.5) were allocated randomly among 8 treatments using a randomized complete block design. Diets were formulated to SID Lys levels of 0.45%, 0.55%, 0.65%, and 0.75%, with or without (0.125%) Lean Fuel in a 4×2 factorial arrangement. All diets contained 3,318 kcal ME/kg. Diets were formulated with corn and soybean meal with no DDGS. SID Lys:ME ranged from 1.35 to 2.26 g/Mcal, respectively and diets were formulated according to ideal protein level where protein level followed SID Lysine level. There were 24-27 pigs/pen with 7-9 replications per treatment. Pens of pigs were weighed and feed disappearance recorded on d 0, 7, 21, and 50 to calculate ADG, ADFI, and G:F. Analysis used the MIXED procedure of SAS with a randomized complete block design. In addition, orthogonal polynomial contrast was used to determine the effect of levels of SID Lys with or without LF. The NLIN procedure of SAS was used for the Broken-line analysis with overall ADG, ADFI, and G:F. During d 7-21, lysine level improved ADG linearly (P<0.05) without LF and quadratically with LF (P<0.05). Diets of 0.55% and 0.65% SID Lysine with LF led to higher G:F than diets of 0.55% and 0.65% without LF (0.285, 0.299 vs 0.276, 0.276; P<0.05 SEM 0.005). Overall, as dietary Lys increased, ADG increased linearly (P<0.01; 858 g, 893 g, 988 g, and 989 g, respectively) without LF and quadratically (P=0.007 SEM 26; 888 g, 975 g, 971 g, and 987 g, respectively) with LF. LF improved G:F (P<0.05) at 0.45% SID Lysine (0.270 vs 0.283) and at 0.55% SID Lysine (0.282 vs 0.294) with no effect on ADG or G:F at 0.65 and 0.75% SID Lysine. Using broken-line analysis, Lys breakpoint for maximum ADG was lower when LF was added (0.67%) in the diet than without (0.69%). However, the breakpoint where lysine achieved the best G:F was much lower at 0.59% as compared to 0.69% when LF was fed. The results of this experiment suggest that the Lysine:ME ratio may need to be adjusted when feeding LF, and this depends on whether ADG or G:F is the key performance criteria.