PSII-13 Effects of Standardized Ileal Digestible Lysine, Fiber Level, and Amino Acid Ratios on Growth Performance of Nursery Pigs

An experiment was conducted to determine the interactive effects of standardized ileal digestible (SID) lysine, dietary fiber, and amino acid ratios on growth performance of nursery pigs. A total of 4,320 pigs (initial BW = 7.8 kg), placed in pens of 36 mixed sex pigs, were used in a 43-d trial. Treatments were arranged in a 2 × 2 × 2 factorial structure with two levels of SID Lys (1.15 or 1.38%), two levels of dietary fiber [control or high fiber (5% sugar beet pulp + 3.75% soy hulls)], and two amino acid ratio profiles [control (65% SID Thr:Lys, 58% SID Met+Cys:Lys, 67% SID Val:Lys, 55% SID Ile:Lys, and 18.5% SID Trp:Lys) or AA+ (5 percentage points greater than control ratios)] with 15 replicates per treatment. The experimental diets were fed from d 0 to 25 and a common corn-soybean meal-based diet was fed from d 25 to 43. Pigs were weighed on d 0, 25, and 43 to calculate ADG, ADFI, and G:F. Data were analyzed with the MIXED procedure in SAS. From d 0 to 25, there was a fiber × amino acid ratio interaction (P= 0.008) for ADFI, where pigs fed the high fiber diet had similar ADFI, regardless of AA ratios, but those fed control levels of fiber had reduced ADFI when fed AA+ ratios (Table 1). Similar interactions were also observed (P< 0.05) for overall (d 0 to 43) ADG, ADFI, and final BW. There were no other significant interactions (P> 0.05). As for main effects, pigs fed low Lys had reduced (P< 0.05) ADG, ADFI, and G:F. Feeding high fiber diets reduced (P< 0.05) G:F but did not impact (P > 0.05) ADG or ADFI. Pigs fed AA+ ratios had improved (P< 0.05) G:F but no evidence for differences (P> 0.05) for ADG or G:F was observed.