Our objective was to determine the effects of increasing standardized ileal digestible (SID) lysine (Lys) levels on growth performance and carcass characteristics of growing-finishing pigs. A total of 1,013 barrows and gilts (PIC337×Camborough, initially 29.2±0.21 kg) were used in a 112-d growth trial with 25 or 26 pigs per pen and 13 pens per treatment in a randomized complete block design. Diets were corn-soybean meal (SBM)-dried distillers grains with solubles-based, and treatments were achieved through the inclusion of SBM at the expense of corn. Diets were fed in 6 phases and formulated to be iso-caloric within each phase. Treatments consisted of: 1) Low Lys: overall dietary SID Lys levels as 87% of PIC2016 Lys requirement; 2) Medium Lys: overall dietary SID Lys levels as 97% of PIC2016 Lys requirement; 3) High Lys: overall dietary SID Lys levels as 106% of PIC2016 Lys requirement. Experimental data were analyzed using generalized linear mixed models with pen as the experimental unit. Pigs fed High or Medium Lys had greater (P< 0.01) average daily gain compared to pigs fed Low Lys. There was no evidence (P >0.10) for the difference between treatments for average daily feed intake. Pigs fed High Lys had the greatest (P< 0.01) feed efficiency (G:F) followed by Medium Lys, with pigs fed Low Lys with the lowest G:F. Pigs fed High or Medium Lys had greater (P< 0.01) hot carcass weight, loin depth, and lean percentage compared to pigs fed Low Lys. There was no evidence (P >0.10) for treatment effect on carcass yield and backfat. Pigs fed Low Lys had greater removal and mortality rate than those fed High or Medium Lys (P< 0.01).

In conclusion, increasing SID Lys over PIC2016 recommendations through increasing SBM levels resulted in increased growth performance and carcass characteristics, and reduced removal and mortality rate of 29- to- 129 kg pigs.

Kitt, S., W. Cast, M. Hover, C. Vier, C. Sievers, N. Lu, A. Betlach, D. Hamilton, R. Kiehne and U. Orlando. 2020. Determining the effects of increasing dietary standardized ileal digestible lysine levels on growth performance and carcass characteristics of growing-finishing pigs from 29- to 129-kg. Midwest Section American Society of Animal Science meeting, research abstract 202.