Evaluation of Sid Lys:ME Ratios in Grow-Finishing Pigs

Approximately 1,200 (400 PIC 337×1050 and 800 PIC359×C29) barrows and gilts (26.5 ± 1.9 kg) were used to evaluate three different SID Lys:ME programs in grow-finish. Experimental diets were fed in 5 phases (26-41, 41-55, 55-82, 82-105, 105-114 kg) with one of 3 SID Lys:ME programs (Current, New and Economical). The SID Lys:ME ratios by phase for each treatment were as follows: Current=3.17, 2.76, 2.38, 2.11, 1.96; New=3.60, 3.00, 2.62, 2.46, 2.09; Economical=3.22, 2.98, 2.53, 2.26, 2.09. Pigs were fed a common diet with Paylean at 4.5 g/Ton and SID Lys:ME=2.87 from 114 kg to market. Diets were formulated to meet or exceed NRC requirements. Growth performance data collected was collected at start and end of study and at the end of each phase. Overall (start of study to end of marketing) morbidity and mortality was determined. Data were analyzed as a randomized complete block design (block = start body weight) using the PROC MIXED procedure of SAS with pen as the experimental unit and treatment as the main effect. Results were considered significant at P ≤ 0.05 and considered a trend at P > 0.05 and P ≤ 0.10. Pigs on the New and Economical treatments tended to be heavier (0.05 > P ≤ 0.1) than the Current Lys:ME treatment on every interim period starting on day 43. At the end of the finishing period (i.e., start of marketing on day 101), pigs on the New and Economical treatments were 2.05 and 2.00 kg heavier than pigs in the Current treatment, respectively. For the cumulative period from start to d 101, the ADG of pigs fed the New and Economical diets (0.89 and 0.89 kg/d, respectively) was greater than that of pigs fed the Current diets (0.87 kg/d). G:F for the cumulative period Day 0-101 was better (P < 0.05) for pigs on the New treatment (0.408) than that of pigs in the Current and Economical treatments (0.401 and 0.404, respectively). However there was no treatment effect (P > 0.1; 0.392, 0.396, 0.394) for the overall period (Day 0-End of Marketing) after feeding a common diet during the marketing period. In conclusion, growth performance of pigs is improved with higher Lys:ME ratios compared to current recommendations. The use of an “Economical” formulation was able to reduce the feeding costs compared to the New recommendations while still maintaining the improvements in growth performance compared to current specifications.