Table 3.

Effect of heat stress on the performance of broilers and guanidinoacetic (GAA) acid intervention effect

Items2	Treatment1				P-value
	NC	HS	PF	HG	ANOVA	HS vs. HG
BW at d 28, g/bird	1458.3 ± 5.4	1452.5 ± 12.0	1452.5 ± 6.9	1464.4 ± 3.4	0.858	0.365
BW at d 35, g/bird	2077.9 ± 21.6a	1855.7 ± 31.8b	2017.9 ± 22.4a	1957.9 ± 35.1	<0.001	0.068
BW at d 42, g/bird	2637.3 ± 50.0a	2149.4 ± 65.9b	2457.7 ± 68.8a	2326.5 ± 63.9	<0.001	0.083
Heat exposure for 7 d
ADG, g/bird/day	88.5 ± 3.1a	57.6 ± 4.0b	80.8 ± 3.9a	69.3 ± 4.4	<0.001	0.077
ADFI, g/bird/day	152.3 ± 5.7a	125.7 ± 4.4b	131.6 ± 4.8b	133.7 ± 3.5	0.005	0.186
F/G, g/g	1.72 ± 0.04b	2.21 ± 0.10a	1.64 ± 0.04b	1.95 ± 0.09	<0.001	0.075
Heat exposure for 14 d
ADG, g/bird/day	84.2 ± 3.8a	49.8 ± 5.4b	71.8 ± 5.0a	61.6 ± 4.3	<0.001	0.119
ADFI, g/bird/day	163.2 ± 5.1a	127.1 ± 6.5b	131.7 ± 5.3b	141.5 ± 4.3	0.001	0.095
F/G, g/g	1.95 ± 0.09b	2.63 ± 0.37a	1.86 ± 0.17b	2.33 ± 0.22	<0.001	0.112

¹NC, normal control group, 22 ^°C, ad libitum feed basal diet; HS, heat stress group, 32 ^°C, ad libitum feed basal diet; PF, pair-fed group, 22 ^°C, received food equivalent to that consumed by the HS group on the previous day; HG, guanidinoacetic acid group, 32 ^°C, ad libitum feed basal diet with 0.6 g/kg guanidinoacetic acid.

²F/G, feed to gain ratio.

^a,b Means within a row without a common superscript differ significantly among the NC, HS, and PF groups (P < 0.05). The results were expressed as the means ± SE.