Table 5. Effect of combined supplementation of catechin and vitamin C supplementation on stress index in blood of broilers during high temperature

Vitamin C (mg/kg)	0			250			SEM	P-value¹
Catechin (mg/kg)	0	600	1,200	0	600	1,200	SEM	C	V	C × V
Superoxide dismutase (U/mL)	164.58^b	179.57^ab	199.42^a	170.59^ab	178.80^ab	188.99^ab	3.510	0.007	0.791	0.584
Corticosterone (ng/mL)	20.43^a	17.20^ab	10.51^c	17.88^ab	12.63^c	14.33^bc	0.93	0.009	0.413	0.124
IgM (ng/mL)	12.03^a	9.07^ab	5.65^b	11.98^a	8.32^ab	9.84^ab	0.611	0.008	0.321	0.163

Means in same rows with different superscripts are significantly different (P<0.05).
C, catechin; V, vitamin C; C × V, catechin × vitamin C.
IgM, immunoglobulin M.
SEM, standard error of means.