PSVI-3 Estimation of the optimal standardized ileal digestible valine to lysine ratio required for growing-finishing pigs in low crude protein diets

摘要

Aim was to determine standardized ileal digestible Val to Lys ratios for growing - finishing pigs fed low CP diets on performance, BUN and carcass characteristics. SID Val to Lys ratios for BW 42.5 to 70.3 kg, 70.3 to 98.1 kg and 98.1 to 128.7 kg pigs. Pigs (n = 400, 10 pens / treatment, 8 pigs / pen) blocked by BW and randomly assigned to 1 of 5 treatments. Diets were SID Val to Lys of 0.55, 0.60, 0.65, 0.70 and 0.75. Data analyzed as a RCBD with PROC MIXED procedure of SAS with pen (experimental unit), treatment (fixed effect), and BW block (random effect). In phase 1, linear and quadratic increase of ADG (Linear, P = 0.03; Quadratic, P = 0.04), BUN decreased (Linear, P = 0.01; Quadratic, P = 0.04). SID Val:Lys for ADG, linear broken-line and quadratic model were 0.64 and 0.66, respectively. BUN for SID Val:Lys were 0.63 (P = 0.01) and 0.70 (P = 0.04). In phase 2, ADG increased (Linear, P = 0.04; Quadratic, P = 0.01) and G:F increased (Linear, P = 0.02; Quadratic, P = 0.04). a linear (P = 0.04) and quadratic (P = 0.01) increase in ADG. SID Val:Lys ADG were 0.66 and 0.70. with the increase of SID Val:Lys ratios. SID Val:Lys for G:F were 0.70 and 0.75, respectively. In phase 3, the SID Val:Lys to maximize ADG were 0.67 (Linear, P = 0.04) and 0.72 (Quadratic, P < 0.01). as the SID Val:Lys increased. Supplementation of low CP diets with high levels of SID Val:Lys increase decreased (Linear, P = 0.02) fat depth, at 0.65. but no effect on other carcass characteristics. In conclusion, SID Val:Lys requirement for ADG in three phases were 0.64, 0.66, 0.67, and 0.66, 0.70, 0.72, using a linear broken-line and quadratic model respectively. BUN and fat thickness appears to be minimized at Val:Lys ratio of 0.65 and a potential to increase lean percentage.