Table 6. Analysis of free amino acids in breast meat from pig skin collagen-fed broilers (%)

Treatments	NC	PC	T1	T2	T3
Cysteine	0.266	0.249	0.251	0.263	0.265
Methionine	0.575	0.509	0.536	0.553	0.557
Aspartic acid	2.115	1.957	2.021	2.107	2.078
Threonine	1.027	0.957	0.983	1.027	1.011
Serine	0.899	0.862	0.864	0.909	0.893
Glutamic acid	3.322	3.108	3.140	3.323	3.281
Glycine	0.952	0.907	0.925	0.955	0.949
Alanine	1.301	1.196	1.245	1.287	1.276
Valine	1.059	0.954	1.004	1.039	1.031
Isoleucine	1.026	0.918	0.956	1.004	0.998
Leucine	1.905	1.735	1.805	1.879	1.859
Tyrosine	0.724	0.657	0.684	0.712	0.704
Phenylalanine	0.900	0.845	0.859	0.896	0.891
Lysine	2.123	1.883	1.988	2.049	2.026
Histidine	0.837	0.726	0.693	0.707	0.697
Arginine	1.500	1.339	1.404	1.474	1.457
Proline	0.778	0.713	0.739	0.750	0.749

NC, basal diet; PC, basal diet+0.1% fish collagen powder; T1, basal diet+0.1% collagen; T2, basal diet+0.5% collagen; T3, basal diet+1.0% collagen.