Table 3. Effects of stocking density (SD) and dietary supplementation of vitamin C (Vit C) on stress indicators of broiler chickens

Treatment		Stress indicators
SD (birds/m2)	Vit C (mg/kg)	Blood H:L	Feather CORT concentrations (pg/mm)
9	0	0.40	9.2
	200	0.40	10.3
18	0	0.83	18.5
	200	0.75	17.6
SEM (n = 6)		0.038	0.96
Main effect
SD (birds/m2)
9		0.40	9.8
18		0.79	18.0
SEM (n = 12)		0.027	0.68
Vit C (mg/kg)
0		0.61	13.8
200		0.57	14.0
SEM (n = 12)		0.027	0.68
Effect (p-value)	df
SD	1	< 0.01	< 0.01
Vit C	1	0.30	0.91
SD × Vit C	1	0.29	0.31

CORT, corticosterone; H:L, heterophil:lymphocyte.