Table 5. Effects of supplementation of ARG sources and PHE levels on small intestine segment weights (% of BW) and morphometric parameters in cold-stressed broilers fed a CM-based diet at 38 d

Item¹⁾	Small intestine weight	Duodenum				Jejunum				Ileum
Item¹⁾	Small intestine weight	Weight	VH (μm)	CD (μm)	VH:CD	Weight	VH (μm)	CD (μm)	VH:CD	Weight	VH (μm)	CD (μm)	VH:CD
Factorial analysis
ARG sources
ARG	3.11	0.627	1,808.2	269.1	6.76^a	1.28	1,204.2^a	191.04	6.40^a	1.20	825.9^a	150.5^b	5.56^a
GAA	3.23	0.617	1,785.7	273.3	6.57^b	1.36	1,148.7^b	191.62	6.10^b	1.25	803.4^b	160.5^a	5.08^b
SEM	0.050	0.016	8.64	2.08	0.062	0.036	7.51	2.67	0.088	0.028	7.40	2.11	0.082
PHE levels
0 g/kg	3.15	0.611	1,789.9	269.8	6.66	1.31	1,173.0	192.7	6.19	1.23	809.3	156.2	5.27
1.5 g/kg	3.19	0.633	1,804.0	272.5	6.66	1.33	1,179.9	189.9	6.30	1.23	820.0	154.9	5.38
SEM	0.050	0.016	8.64	2.08	0.062	0.036	7.51	2.67	0.088	0.028	7.40	2.11	0.081
ARG sources × PHE levels
ARG × 0 g/kg	3.05	0.605	1,798.4	266.6	6.78	1.26	1,200.3	193.3	6.31	1.19	820.5	151.8	5.48
ARG × 1.5 g/kg	3.17	0.649	1,818.0	271.6	6.74	1.30	1,208.1	188.8	6.48	1.22	831.3	149.2	5.65
GAA × 0 g/kg	3.26	0.618	1,781.4	273.1	6.55	1.36	1,145.6	192.1	6.07	1.28	798.0	160.5	5.05
GAA × 1.5 g/kg	3.20	0.616	1,790.0	273.4	6.59	1.35	1,151.7	191.1	6.12	1.23	808.8	160.5	5.12
SEM	0.072	0.023	12.22	2.95	0.088	0.051	10.6	3.78	0.124	0.039	10.47	2.99	0.115
p-value
ARG sources	0.118	0.664	0.679	0.157	0.033	0.156	<.0001	0.879	0.017	0.216	0.033	0.001	<.0001
PHE levels	0.649	0.354	0.249	0.361	0.993	0.716	0.517	0.477	0.389	0.845	0.305	0.667	0.318
ARG sources × PHE levels	0.205	0.320	0.653	0.428	0.660	0.603	0.935	0.646	0.643	0.307	0.999	0.668	0.674
Orthogonal analysis
NC²⁾	3.59	0.795	1,766.7	280.8	6.31	1.50	1,082.6	198.4	5.53	1.30	777.7	164.8	4.80
EG³⁾	3.17	0.622	1,796.9	271.2	6.67	1.32	1,176.4	191.3	6.25	1.23	814.7	155.5	5.33
GAA⁴⁾	3.23	0.617	1,785.7	273.25	6.57	1.36	1,148.7	191.6	6.10	1.26	803.4	160.5	5.09
p-value Ӏ⁵⁾	< .0001	< .0001	0.028	0.003	0.0002	0.002	< .0001	0.088	< .0001	0.109	0.001	0.007	< .0001
p-value Ⅱ⁶⁾	< .0001	< .0001	0.204	0.033	0.014	0.023	< .0001	0.134	0.0001	0.336	0.041	0.249	0.041

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; BW, body weight; CM, canola meal; VH, villus height; CD, crypt depth; VH:CD, villus height to Crypt depth ratio; GAA, guanidinoactic acid.