Table 1.
Variability of crude protein (CP) and amino acids among six origins of corn (%, as-is basis)

Origin	Amino acids (%)
	CP	Lys	Met	Cys	Thr	Met:Lys	Cys:Lys	Thr:Lys
Within country
Argentina
n1	30	18	18	18	18	18	18	18
Average	7.25	0.18	0.12	0.15	0.22	0.67	0.82	1.25
CV2	4.51	19.21	14.49	16.53	11.18	13.99	16.92	13.22
Brazil
n1	57	34	34	34	34	34	34	34
Average	7.12	0.21	0.12	0.15	0.24	0.60	0.76	1.17
CV2	2.92	13.13	23.22	14.27	7.89	18.09	15.02	8.56
China
n1	56	56	56	56	56	56	56	56
Average	7.60	0.24	0.14	0.17	0.27	0.62	0.71	1.16
CV2	2.88	14.91	13.68	10.13	8.43	17.54	14.51	15.15
India
n1	11	11	11	11	11	11	11	11
Average	7.68	0.22	0.14	0.16	0.26	0.64	0.76	1.17
CV2	5.2	11.2	17.7	14.5	6.6	25.9	23.0	9.5
Ukraine
n1	25	14	14	14	14	14	14	14
Average	7.43	0.21	0.13	0.14	0.25	0.63	0.69	1.18
CV2	5.03	14.23	14.88	8.90	10.31	11.66	12.11	11.96
USA
n1	251	192	192	192	192	192	192	192
Average	7.17	0.21	0.13	0.16	0.25	0.63	0.74	1.16
CV2	5.25	15.11	16.56	13.08	7.95	18.00	14.70	10.58
NRC (2012)
n1	163	132	130	112	129
Average	8.24	0.25	0.18	0.19	0.28	0.71	0.76	1.12
INRA (2003)
n1	2,634	2,634	2,634	2,634	2,634
Average	8.10	0.24	0.17	0.20	0.30	0.71	0.83	1.25
Among countries
n	430	325	325	325	325	325	325	325
Minimum	7.12	0.18	0.12	0.14	0.22	0.60	0.69	1.16
Maximum	7.68	0.24	0.14	0.17	0.27	0.67	0.82	1.25
Average3	7.14	0.22	0.13	0.16	0.25	0.63	0.74	1.17
CV2	3.26	8.72	7.43	5.90	6.73	4.05	5.98	2.95
SEM4	0.338	0.032	0.022	0.020	0.021	0.112	0.113	0.135
P-value	<0.001	<0.001	<0.001	<0.001	<0.001	0.490	0.002	0.099

Values represent the number of observations of nutrient contents in corn to the corresponding country of origins or the publications.
CV=coefficient of variation.
Average values are calculated as a weighted average.
SEM=standard error of the mean.