78 Evaluation of the growth performance of finishing pigs (Genesus genetics) to titrated levels of dietary lysine

Abstract

Abstract A total of 1,000 Genesus (Oakville, Manitoba, Canada) genetics pigs (51.8 kg body weight) were used to estimate the standardized ileal digestible (SID) lysine requirement by dietary phase. Pigs were penned by sex at 25 pigs per pen. Pens were allotted to one of five dietary treatments in a completely randomized design with eight replicate pens (four barrow, four gilt) per treatment. Growth performance was evaluated in four independent phases in which pens were re-allotted to dietary treatment between phases. Dietary SID Lys concentrations evaluated were 0.78, 0.88, 0.98, 1.08, and 1.18% for phase 1, 0.68, 0.77, 0.86, 0.95, and 1.04% for phase 2, 0.60, 0.67, 0.75, 0.83 and 0.90% for phase 3, and 0.53, 0.60, 0.67, 0.74, and 0.81% for phase 4. Diets were formulated to be isoenergetic within each phase. During phase 1 (52-64 kg), average daily gain (ADG) and gain to feed ratio (G:F) increased (P < 0.01) quadratically with increasing SID Lys. Breakpoint analysis estimated the SID Lys requirement for ADG and G:F for phase 1 at 0.99 and 1.02%, respectively. During phase 2 (64-82 kg), ADG increased (P < 0.10) quadratically as dietary SID Lys increased with a plateau observed above 0.86% SID Lys. Gain:feed increased linearly (P < 0.01) with increasing SID Lys. During phase 3 (82-97 kg) cost of gain was a quadratic response (P < 0.10) with the breakpoint being at 0.76% SID Lys. During phase 4 (97-131 kg), a linear response (P < 0.02) in G:F was observed with increasing SID Lys but with no improvement above 0.67% SID Lys. These data indicate the SID lysine requirement for Genesus finishing pigs to be approximately 0.99% (23.0 g/d) for 52-64 kg, 0.86% (21.9 g/d) for 64-82 kg, 0.76% (20.2 g/d) for 82-97 kg, and 0.67% (21.6 g/d) 97-131 kg.