118 Increased Growth and Carcass Attributes in Improvest®-treated Gilts Do Not Require Additional Dietary Lysine

Numerous studies have shown that gilts treated with Improvest® have greater carcass weights and increased ADG compared with untreated gilts. To develop the optimum nutritional program for Improvest-treated gilts, a randomized 5×2 factorial design of dietary lysine levels (90, 100, 110, 120, and 130% of NRC recommendations) with or without Improvest was performed. Gilts were housed in 120 pens (4 pigs/pen) at 8 weeks of age (day 0). Gilts and feed were weighed immediately prior to each dietary phase change (days 0, 21, 42, 70, 91, and 105). Improvest was administered at 9 and 19 weeks of age (4 weeks pre-harvest). There was no diet × treatment × day (P > 0.78) nor diet × treatment (P > 0.11) interactions for any variables. Gilts had similar BWT, ADG, and ADFI until after the 2nd dose of Improvest, when Improvest-treated gilts were heavier (123.62 vs. 121.59 ± 0.68 and 138.16 vs. 133.97 ± 0.71 kg, days 91 and 105; P < 0.01), had increased ADG (1.19 vs. 1.09 ± 0.01 and 1.03 vs. 0.88 ± 0.02 kg/day days 91 and 105; P < 0.01) and consumed more feed (2.99 vs. 2.84 ± 0.03 and 3.19 vs. 2.68 ± 0.04 kg/pig/day; days 91 and 105; P < 0.01) compared with untreated gilts. Carcass evaluation was conducted on 120 pigs (2 pigs/60 pens). No significant structures were present on ovaries of Improvest-treated gilts. Improvest-treated gilts were heavier (market and HCW; P ≤ 0.02) than controls. Improvest-treated gilts tended (P ≤ 0.08) to have heavier bone-in butt and bone-in ham weights. Belly weights were heavier (kg and %HCW; P ≤ 0.05) in Improvest-treated vs control gilts and were thicker (P = 0.01) but were similar (P > 0.3) in length and width. While IV was similar (P > 0.2) in belly fat, loin intramuscular fat was increased (P < 0.01) from Improvest-treated gilts. Without additional dietary amino acids, Improvest-treated gilts delivered greater gain after the 2nd dose, yielding significantly heavier carcasses and primal cuts, including bellies which were larger as a percentage of HCW, and increased loin intramuscular fat.