Table 4.

Effects of graded levels of dietary squalene supplementation on the plasma antioxidant status of broiler chickens.

Items	Squalene level (mg/kg)					SEM	P-values
	0	250	500	1,000	2,000		ANOVA	Linear	Quadratic
21 d
MDA (nmol/mL)	1.94a	1.60b	1.43b,c	1.49b,c	1.25c	0.062	0.002	<0.001	0.294
GSH (mg/L)	9.28b	9.59b	9.48b	13.68a	13.58a	0.550	0.002	<0.001	0.340
SOD (U/mL)	165.65	175.15	166.42	154.43	167.70	4.478	0.727	0.617	0.913
GSH-Px (U/mL)	683.92	691.75	700.30	694.36	685.10	10.590	0.990	0.951	0.613
42 d
MDA (nmol/mL)	2.05a	1.82a,b	1.33c	1.56b,c	1.40c	0.065	<0.001	<0.001	0.032
GSH (mg/L)	8.99b	8.79b	9.42b	9.77a,b	10.89a	0.239	0.032	0.004	0.189
SOD (U/mL)	180.54b	178.33b	175.67b	205.83a	203.18a	3.630	0.004	0.002	0.203
GSH-Px (U/mL)	726.90a	743.91a	720.46a	672.64a,b	616.78b	13.139	0.006	0.001	0.069

^a-cMeans within a row with different superscripts are different at P < 0.05.

Abbreviations: GSH, reduced form of glutathione; GSH-Px, glutathione peroxidase; MDA, malondialdehyde; SOD, superoxide dismutase.