Table 5.

Effect of guanidinoacetic acid (GAA) supplementation on kidney creatine metabolism, malondialdehyde (MDA) concentration, and antioxidant enzyme activities (superoxide dismutase, SOD, and glutathione peroxidase, GPx) of male broilers subjected to heat stress in the finisher phase at d 26 and 39¹ (n = 12).

Item	Dietary treatment			SEM	P value
Supplemental GAA, g/kg	0.0	0.6	1.2		Model	Linear	Quadratic
Total creatine, mg/kg
d 26	4.7	11.9	6.4	1.5	0.120	0.678	0.042
d 39	8.7	9.1	10.8	4.2	0.102	0.042	0.476
Creatinine, mg/kg
d 26	1.2	1.2	1.6	0.07	0.073	0.038	0.320
d 39	1.1	1.2	1.1	0.06	0.843	0.976	0.565
GAA, mg/kg
d 26	33.7	65.4	62.0	12.9	0.583	0.394	0.527
d 39	15.1	14.3	15.5	1.75	0.957	0.913	0.789
MDA, nmol/g
d 26	33	34	34	1.1	0.871	0.807	0.644
d 39	31	32	32	0.27	0.344	0.366	0.251
SOD, U/g
d 26	209	203	204	5.2	0.898	0.727	0.764
d 39	218	210	223	3.9	0.446	0.613	0.246
GPx, U/g
d 26	3.8	4.0	4.0	0.06	0.249	0.159	0.370
d 39	4.7	4.7	4.6	0.08	0.983	0.869	0.939

¹Broilers were fed a corn-soybean starter diet from d 0 to 10, a grower diet from d 10 to 25, and a finisher diet from d 25 to 39.