Effect of Increasing Standardized Ileal Digestible Lysine on Growth Performance of PIC 408 × X54 Commercial Pigs During the Late-nursery Phase

Abstract The present study aimed to investigate the effect of increasing the standardized ileal digestible lysine (SID Lys) on growth performance during the late-nursery phase in PIC 408 × X54 commercial pigs. A total of 1,536 barrows and gilts Pietrain × (Large White × Landrace) were used in a 48 d nursery trial with 96 mixed sex pens (16 pigs per pen). At the beginning of the trial, pens were blocked by body weight (BW) and randomly allotted to one of four treatments (overall dietary SID Lys level as 4.37, 4.78, 5.14, or 5.65 g SID Lys:Mcal of Net Energy (NE), which corresponded to 85, 93, 100, or 110% of PIC SID Lys recommendations, respectively) in a randomized complete block design. One feeder was present every two pens, so there was total of 48 experimental units. Barley-wheat-maize-soybean meal based diets were used and all diets were isoenergetic. Treatment diets were applied in the late-nursery phase, starting at 12.8 ± 0.51 kg of BW. Feed intake was recorded daily and pens were weighed at the end of the trial, so average daily gain (ADG), average daily feed intake (ADFI), and feed conversion ratio (FCR) were calculated. Mortality and removals were collected during the trial period. Feeder was considered the experimental unit. Performance data were analyzed using generalized linear mixed models and survival data were analyzed using a general linear model with data treated as binomial in R. The statistical model considered SID Lys level as fixed effect and block was included as random effect. Alpha for determination of significance was 0.05 and trend were identified at 0.10. Pigs fed 5.14 and 5.65 g SID Lys:Mcal NE were 1.72 and 2.66 kg heavier at the end of the trial compared to pigs fed 4.78 and 4.37 g SID Lys:Mcal NE, respectively (Table 1;P 0.001). Similarly, pigs fed 5.14 and 5.65 g SID Lys:Mcal NE gained 53.5 and 86.5 g/d more compared to pigs fed 4.78 and 4.37 g SID Lys:Mcal NE, respectively (P 0.001). Pigs fed 5.14 g SID Lys:Mcal NE had 42 g/d higher intake compared to pigs fed 4.37 g SID Lys:Mcal NE (P = 0.006). Feed efficiency was also linearly improved with pigs fed 5.14 and 5.65 g SID Lys:Mcal NE being more feed efficient (P 0.001). No differences were found on removals and mortality (P 0.05). In conclusion, results suggest that increased SID Lys to Mcal NE ratio improves growth performance in late-nursery pigs sired by PIC 408 up to 5.14 g SID Lys:Mcal NE.