. 2020 Jun 26;6(3):305–312. doi: 10.1016/j.aninu.2020.04.003

Table 2.

Relative expression of the Keap1/NRf2/ARE pathway genes along the intestinal mucosa of 42-d-old broilers.

Item¹	Treatments²				SEM	P-values³
Item¹	CON	PP-750	PP-1000	PP-2000	SEM	P_ANOVA	P_lin	P_quad
Duodenum
CAT	1.02	1.44	0.94	0.94	0.200	0.219	0.243	0.143
SOD1	0.83^a	1.29^bc	1.35^c	0.92^ab	0.200	0.027	0.614	0.003
GPX2	1.14^ab	1.28^ab	1.98^b	0.84^a	0.292	0.032	0.830	0.004
HMOX1	0.78^a	1.20^ab	1.44^b	1.17^ab	0.224	0.046	0.055	0.037
NQO1	0.86^a	1.24^b	1.20^b	1.07^ab	0.146	0.050	0.193	0.017
Nrf2	1.02	1.20	1.20	1.04	0.231	0.782	0.925	0.307
Keap1	0.83^a	1.39^b	1.31^b	0.99^ab	0.202	0.027	0.554	0.004
Jejunum
CAT	1.02	1.22	1.00	1.08	0.197	0.661	0.961	0.641
SOD1	0.90^a	1.40^b	0.96^ab	1.06^ab	0.171	0.026	0.937	0.111
GPX2	0.69^a	1.71^b	1.89^b	0.98^ab	0.405	0.013	0.075	0.004
HMOX1	0.90	1.00	1.14	1.27	0.147	0.085	0.011	0.845
NQO1	0.86^a	1.23^b	1.11^ab	1.14^ab	0.156	0.011	0.155	0.124
Nrf2	1.37	1.67	1.38	1.24	0.406	0.757	0.592	0.448
Keap1	0.92	1.11	1.13	1.07	0.157	0.535	0.353	0.259
Ileum
CAT	0.96	1.13	1.11	1.15	0.193	0.738	0.362	0.627
SOD1	0.91	1.09	1.18	1.10	0.182	0.301	0.246	0.309
GPX2	0.89	1.13	1.38	1.27	0.236	0.057	0.068	0.301
HMOX1	0.98	1.14	1.34	1.12	0.203	0.370	0.340	0.184
NQO1	0.87	1.22	1.37	1.32	0.199	0.067	0.022	0.158
Nrf2	0.99	1.46	1.10	1.28	0.258	0.294	0.548	0.427
Keap1	0.87	1.09	1.39	1.12	0.190	0.076	0.086	0.080
Ceca
CAT	1.03	1.54	1.67	0.90	0.453	0.263	0.858	0.053
SOD1	0.70^a	1.40^b	1.42^b	1.06^ab	0.255	0.023	0.181	0.006
GPX2	0.78^A	1.11^AB	1.13^AB	1.59^B	0.212	0.006	0.001	0.684
HMOX1	0.89^a	1.60^b	1.31^ab	0.94^a	0.245	0.019	0.860	0.003
NQO1	0.74^a	1.29^b	1.13^ab	1.32^b	0.198	0.022	0.016	0.210
Nrf2	0.76^a	1.27^ab	1.69^b	1.12^ab	0.286	0.024	0.107	0.012
Keap1	0.72^A	1.52^C	1.26^BC	1.00^AB	0.162	<0.001	0.254	<0.001

Keap1 = kelch like ECH associated protein 1; Nrf2 = nuclear factor (erythroid-derived 2)-like 2; ARE = antioxidant response element; SEM = pooled standard error of means; CAT = catalase; SOD1 = superoxide dismutase 1; GPX2 = glutathione peroxidase 2; HMOX1 = heme oxygenase 1; NQO1 = NAD(P)H quinone dehydrogenase 1.

Relative expression ratios of target genes were calculated according to Pfaffl (2001) adapted for the multi-reference genes normalization procedure according to Hellemans et al. (2007) using glyceraldehyde 3-phosphate dehydrogenase (GAPDH), actin, beta (ACTB) and peptidylprolyl isomerase A (PPIA) as reference genes.

CON, basal diet with no phytogenic premix (PP) addition; PP-750, basal diet containing PP at 750 mg/kg diet; PP-1000, basal diet containing PP at 1,000 mg/kg diet; PP-2000, basal diet containing PP at 2,000 mg/kg diet. Data represent treatment means from n = 10 broilers analyzed per treatment.

The statistical analysis tests the differences between treatments (ANOVA) and the linear (lin) and quadratic (quad) effect of PP inclusion levels (polynomial contrasts). Means within the same row with different superscripts (a, b) differ at P < 0.05 and with different superscripts (A, B, C) differ at P < 0.01.