Broiler responses to copper levels and sources: growth, tissue mineral content, antioxidant status and mRNA expression of genes involved in lipid and protein metabolism

Table 3 Optimum supplemental copper (Cu) level for broiler chicks considering sources individually or combined

Item	Regression Eqs. ¹	Optimal supplemental Cu level. mg/kg²	P-value	Coefficient of determination (R²)
*Body weight*
Copper levels	y = − 0.1003x² + 1.3533x + 505.73	6.75	0.042	5.36
CuPro	y = − 0.1296x² + 1.9294x + 505.78	7.44	0.066	6.73
*Average daily gain*
Copper levels	y = − 0.0101x² + 0.1352x + 33.81	6.76	0.045	5.33
CuPro	y = − 0.0129x² + 0.1926x + 33.82	7.47	0.067	6.63
*Feed conversion ratio*
Copper levels	y = 0.00049x² − 0.0091x + 1.3182	9.31	0.002	11.4
CuPro	y = 0.00044x² − 0.0088x + 1.3038	9.87	0.041	13.7
CuSO_4.5H₂O	y = 0.00054x² − 0.0095x + 1.3325	8.84	0.014	13.3

CuPro (organic), copper proteinate and organic trace minerals; CuSO₄.5H₂O (inorganic), copper sulphate and inorganic trace minerals
¹Regression equations obtained from fitting performance data to polynomial quadratic regression model Y is dependent variable and X is the supplementation Cu concentration in the corresponding diet (mg/kg)
²Cu/kg diet to a semi-purified diet containing 1.32 mg Cu/kg

ISSN: 1746-6148