Table 3. Effect of different dietary copper (Cu) sources and levels on apparent total tract digestibility (ATTD) of Cu in growing pigs (n = 6/treatment).

Cu source	Added Cu level (mg/kg)	ATTH (%)
CuSO4	0	34.03bc
	50	34.79bc
	100	28.60c
CuAA	0	34.03bc
	50	54.19a
	100	45.89ab
CuHMB	0	34.03bc
	50	46.30ab
	100	48.96a
SEM		2.99
p-value for source × level		< 0.0001
Main effect of source
CuSO4		32.47b
CuAA		44.70a
CuHMB		43.10a
SEM		2.22
p-value for source		0.001
Main effect of level
	0	34.03b
	50	45.09a
	100	41.15ab
SEM		2.33
p-value for level		0.006

^a-cValues with different superscripts in the same column are significantly different (p < 0.01).

CuSO₄, copper sulfate; CuAA, Cu-amino acid complex; CuHMB, Cu-hydroxy-4-methylthio butanoate chelate complex.