Table 5.

Serum immune index of Ningdu yellow chickens.

Items	Additive amount of TCP					SEM	P value
	0.0%	0.2%	0.4%	0.6%	0.8%		ANOVA	Linear	Quadratic
43–70 d
IgG (g/L)	3.82b	4.19a	4.08ab	4.14a	4.18a	0.05	0.049	0.031	0.041
IgM (g/L)	1.22b	1.40a	1.37a	1.39a	1.31a	0.02	0.001	0.122	<0.001
IgA (g/L)	2.30b	2.44a	2.47a	2.54a	2.54a	0.02	0.001	<0.001	<0.001
TP (g/L)	19.62	21.75	19.65	20.85	21.32	0.90	0.931	0.740	0.947
lL-2 (pg/mL)	322.11a	290.78a	232.88b	230.24b	287.58a	7.35	<0.001	0.011	<0.001
lL-4 (pg/mL)	7.36b	8.17b	10.64a	10.73a	8.47b	0.25	<0.001	0.005	<0.001
TNF-α (pg/mL)	64.25	59.03	55.94	55.54	58.07	1.28	0.198	0.075	0.047
IFN-γ (pg/mL)	45.34	42.33	41.67	41.52	42.01	0.64	0.306	0.097	0.094
71–105 d
IgG (g/L)	5.14	5.29	5.18	5.39	5.23	0.12	0.975	0.756	0.911
IgM (g/L)	1.69	1.70	1.71	1.89	1.73	0.04	0.492	0.375	0.590
IgA (g/L)	2.91	2.96	3.00	3.12	3.03	0.06	0.861	0.357	0.604
TP (g/L)	23.45	23.55	28.44	31.20	30.41	1.75	0.471	0.079	0.209
lL-2 (pg/mL)	259.07a	236.12ab	221.25bc	209.35c	246.36ab	4.39	0.001	0.099	<0.001
lL-4 (pg/mL)	9.57b	10.10b	11.20a	11.83a	10.12b	0.18	<0.001	0.025	<0.001
TNF-α (pg/mL)	46.57	45.54	45.15	41.10	39.42	1.20	0.252	0.026	0.073
IFN-γ (pg/mL)	37.73	35.53	36.92	34.53	36.25	0.82	0.780	0.500	0.672

Values are the means and SEM of 12 broilers (2 broilers per replicate).

^a–cMeans within a row lacking a common superscript differ significantly (P < 0.05).

Abbreviations: IFN-γ, interferon-γ; IgA, immunoglobulin A; IgG, immunoglobulin G; IgM, immunoglobulin M; IL-2, interleukin-2; IL-4, interleukin-4; SEM, standard error of the mean; TCP, traditional Chinese prescription; TNF-α, tumor necrosis factor-α; TP, total protein.