Table 7. Effects of supplementation of ARG sources and PHE levels on apparent ileal digestibility of DM, CP, EE, CF, and GE in cold-stressed broilers fed a CM-based diet at 38 d

Item1) DM (%) CP (%) EE (%) CF (%) GE (%)
Factorial analysis
 ARG sources
  ARG 77.42a 77.82 87.87b 23.16 74.83
  GAA 76.09b 76.19 89.60a 22.84 75.24
  SEM 0.346 0.634 0.510 0.263 0.667
 PHE levels
  0 g/kg 76.76 76.95 88.05 22.87 75.01
  1.5 g/kg 76.75 77.06 89.42 23.13 75.03
  SEM 0.346 0.634 0.510 0.263 0.667
 ARG sources × PHE levels
  ARG × 0 g/kg 77.56 77.49 87.08 22.96 74.94
  ARG × 1.5 g/kg 77.28 78.14 88.65 23.35 74.72
  GAA × 0 g/kg 75.96 76.40 89.02 22.79 75.08
  GAA × 1.5 g/kg 76.22 75.99 90.18 22.91 75.40
  SEM 0.489 0.896 0.721 0.372 0.943
p-value
  ARG sources 0.015 0.089 0.029 0.415 0.670
  PHE levels 0.980 0.899 0.076 0.496 0.960
  ARG sources × PHE levels 0.591 0.563 0.773 0.736 0.777
Orthogonal analysis
 NC2) 74.59 73.11 86.07 21.93 70.53
 EG3) 76.76 77.01 88.73 23.00 74.04
 GAA4) 76.09 76.20 89.60 22.85 75.24
p-value Ӏ5) 0.006 0.002 0.002 0.015 0.0003
p-value Ⅱ6) 0.064 0.018 0.0003 0.052 0.0005
Means in the same column with different superscripts differ significantly (p < 0.05).
NC: negative control group (birds fed CM-based diets without supplements), n = 6 replicates; for each replicate, n = 15 birds.
EG: experimental groups (other four treatments fed diets with supplements), n = 24 replicates; for each replicate, n = 15 birds.
GAA: GAA supplemented groups, n = 12 replicates; for each replicate, n = 15 birds.
Ӏ: orthogonal contrast of NC vs. EG
Ⅱ: orthogonal contrast of NC vs. GAA.
ARG, arginine; PHE, phenylalanine; DM, dry matter; CP, crude protein; EE, ether extract; CF, crude fiber; GE, gross energy; GAA, guanidinoactic acid.