Table 5. Effects of different dietary copper (Cu) sources and levels on mineral concentrations (mg/L) in serum of growing pigs (n = 6/treatment)

Cu source	Added Cu level (mg/kg)	Cu	Fe	Zn	P	S
CuSO₄	0	1.49	2.04	0.53^a	123.81^b	883.80^c
	50	1.64	2.50	0.52^a	119.97^b	904.06^c
	100	1.64	1.81	0.50^ab	125.54^b	907.96^c
CuAA	0	1.49	2.04	0.53^a	123.81^b	883.80^c
	50	1.68	1.14	0.45^b	125.99^b	927.88^c
	100	1.56	2.06	0.48^ab	133.53^b	941.55^bc
CuHMB	0	1.49	2.04	0.53^a	123.81^b	883.80^c
	50	1.70	2.26	0.45^b	162.38^a	1,067.39^b
	100	1.70	1.17	0.46^b	182.12^a	1,206.14^a
SEM		0.09	0.43	0.02	5.30	28.96
p-value for source × level		0.255	0.287	0.002	< 0.0001	< 0.0001
Main effect of source
CuSO₄		1.59	2.12	0.52	123.11^b	898.60^b
CuAA		1.57	1.71	0.49	127.78^b	917.74^b
CuHMB		1.63	1.81	0.48	156.10^a	1,052.44^a
SEM		0.05	0.26	0.01	4.49	24.55
p-value for source		0.729	0.520	0.097	< 0.0001	< 0.0001
Main effect of level
	0	1.49^b	2.04	0.53^a	123.81^b	883.80^b
	50	1.67^a	1.97	0.47^b	136.11^ab	966.44^ab
	100	1.63^ab	1.66	0.48^b	147.06^a	1,018.55^a
SEM		0.05	0.25	0.01	5.23	26.40
p-value for level		0.026	0.558	0.004	0.011	0.003

Values with different superscripts in the same column are significantly different (p < 0.05).
CuSO₄, copper sulfate; CuAA, Cu-amino acid complex; CuHMB, Cu-hydroxy-4-methylthio butanoate chelate complex.