LAUSR

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.