Table 1.

Effect of guanidinoacetic acid (GAA) supplementation on plasma creatine metabolism, energy metabolites, 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 treatment2			SEM	P value
Supplemental GAA, g/kg	0.0	0.6	1.2		Model	Linear	Quadratic
Guanidinoacetic acid, μmol/L
d 26	0.5c	6.3b	14.3a	1.15	<0.001	<0.001	0.458
d 39	0.5c	3.8b	7.4a	0.50	<0.001	<0.001	0.620
Total creatine, μmol/L
d 26	78b	127ab	170a	11.3	0.002	<0.001	0.906
d 39	72b	84b	121a	5.0	<0.001	<0.001	0.122
Homocysteine, μmol/L
d 26	57	57	61	1.7	0.558	0.324	0.688
d 39	48	45	50	1.5	0.427	0.661	0.222
Arginine, μmol/L
d 26	263b	311ab	344a	12.8	0.029	0.009	0.752
d 39	226	271	302	16.9	0.185	0.070	0.847
Creatine kinase, U/mL
d 26	17	16	13	1.5	0.543	0.277	0.878
d 39	20	17	25	1.8	0.229	0.268	0.187
Lactate, mmol/L
d 26	3.1	3.4	3.3	0.33	0.943	0.817	0.803
d 39	2.2	2.0	2.0	0.12	0.720	0.477	0.704
Cholesterol, mmol/L
d 26	3.9	3.8	3.6	0.07	0.111	0.048	0.498
d 39	3.9	3.5	3.4	0.10	0.116	0.055	0.421
Triglycerides, mmol/L
d 26	1.6	1.3	1.7	0.08	0.108	0.745	0.038
d 39	1.0	1.2	1.0	0.09	0.708	0.923	0.413
Glucose, mmol/L
d 26	18	18	16	0.4	0.060	0.041	0.219
d 39	17	17	16	0.2	0.133	0.360	0.073
MDA, μmol/L
d 26	14	14	13	0.2	0.261	0.225	0.267
d 39	14	14	13	0.2	0.876	0.615	0.927
SOD, U/mL
d 26	42	41	49	4.4	0.739	0.510	0.689
d 39	49	72	67	5.1	0.472	0.378	0.353
GPx, U/mL
d 26	1.4	1.6	1.4	0.05	0.318	0.970	0.133
d 39	1.3	1.2	1.2	0.03	0.256	0.187	0.318

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.

²Values with different superscripts (a–c) within a row are significantly different at P < 0.05.