Effect of Dietary Standardized Ileal Digestible Lysine Concentration Curve on Growth Performance and Carcass Characteristics of Finishing Pigs of DNA Genetics.

A total of 1,125 pigs (31.4 kg BW) of DNA genetics were used in a 109-d experiment to evaluate the effect of SID Lys feeding curve of pigs from 31.4 to 133.3 kg BW. Forty-five pens of mixed sex pigs were used. Pens were blocked by location within the barn with barrow and gilt numbers in pens kept consistent within block. Pens were allotted to one of five dietary treatments in a randomized complete block design with 9 replicate pens per treatment. Dietary SID lysine concentrations were evaluated on a curve (corresponding to 90, 95, 100, 105, and 110% of the DNA Genetics SID lysine recommendations) using a 6-phase feeding program throughout the experimental period. The 100% curve concentrations used were 1.16% for phase 1 (31.4 - 47.5 kg), 1.02% for phase 2 (47.5 - 64.4 kg), 0.92% for phase 3 (64.4 - 81.8 kg), 0.79% for phase 4 (81.8 - 98.9 kg), 0.72% for phase 5 (98.9 - 117.1 kg), and 0.65% for phase 6 (117.1 - 133.3 kg). Diets were corn-soybean meal-DDGS-based and formulated for equal NE concentrations across treatment within diet phase. Data were analyzed using a general linear model. Orthogonal contrasts with coefficients for equally spaced treatments were used to analyze for linear and quadratic effects. A linear (P < 0.05) increase was observed for BW, average daily gain, and G:F as SID lysine level in the diet increased. There was a linear increase observed (P < 0.05) for lysine intake (g/d and g per lb. gain) as SID lysine level of the diet increased. While no difference (P > 0.10) was observed for NE intake, caloric efficiency improved linearly (P < 0.05) as lysine level in the diet increased. Furthermore, return over feed cost improved linearly (P < 0.05) as dietary SID lysine level increased. There was no effect of SID lysine level fed on mortality and morbidity. A linear response (P < 0.05) for hot carcass weight and loin depth was observed as SID lysine level increased. Additionally, a quadratic response was observed (P < 0.05) for fat depth and percent lean as SID lysine level increased. These data indicate the SID lysine level that optimized growth and carcass measurements for DNA pigs ranging from 31.4 to 133.3 kg to be above the 105% curve, corresponding to 1.22, 1.071, 0.966, 0.83, 0.756, and 0.683 for diet phases 1 through 6, respectively. [ABSTRACT FROM AUTHOR]