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Table 9 Estimation of dietary Cu requirements for weanling pigs fed diets with TBCC or CuPro based on broken-line regression analysis

From: Optimal dietary copper requirements and relative bioavailability for weanling pigs fed either copper proteinate or tribasic copper chloride

Dependent variables Copper source1 Regression equation2 RMSE3 Dietary Cu requirement4, mg/kg
ADG TBCC Y = 357.15–0.420 × (X < 140.65) × (140.65 − X) 18.03 140
CuPro Y = 361.37–0.800 × (X < 80.00) × (80.00 − X) 30.20 80
FCR TBCC Y = 1.445 + 0.0018 × (X < 119.93) × (119.93 − X) 0.023 120
CuPro Y = 1.423 + 0.0030 × (X < 73.81) × (73.81 − X) 0.022 74
ALP TBCC Y = 2.973–0.009 × (X < 148.33) × (148.33 −X) 0.144 148
CuPro Y = 3.048–0.014 × (X < 97.55) × (97.55 − X) 0.122 98
Bile Cu TBCC Y = 3.216–0.0267 × (X < 93.38) × (93.38 − X) 0.207 93
CuPro Y = 3.228–0.0360 ×(X < 69.10) × (69.10 − X) 0.269 69
CER TBCC Y = 84.58–0.252 × (X < 50.00) × (50.00 − X) 3.73 50
CuPro Y = 85.92–1.079 × (X < 26.50) × (26.50 − X) 5.32 27
Cu/Zn SOD TBCC Y = 146.03–0.194 × (X < 102.67) × (102.67 − X) 12.58 103
CuPro Y = 152.33–0.473 × (X < 62.72) × (62.72 − X) 11.94 63
GSH-Px TBCC Y = 748.73–0.272 × (X < 75.59) × (75.59 − X) 3.71 76
CuPro Y = 757.54–0.337 × (X < 88.37) × (88.37 − X) 4.84 88
MDA TBCC Y = 1.81 + 0.0070 × (X < 84.87) × (84.87 − X) 0.279 85
CuPro Y = 1.77 + 0.0116 × (X < 49.80) × (49.80 − X) 0.20 50
T-AOC TBCC Y = 0.709–0.0010 × (X < 105.12) × (105.12 − X) 0.141 105
CuPro Y = 0.711–0.0012 × (X < 77.67) × (77.67 – X) 0.101 78
  1. 1TBCC  tribasic copper chloride, CuPro copper proteinate
  2. 2 Y is the dependent variable and X is the supplementation Cu concentration in the corresponding diet (mg/kg)
  3. 3 RMSE: root mean squared error
  4. 4 Dietary Cu requirement = Supplemental Cu level
  5. ALP alkaline phosphatase, CER ceruloplasmin, Cu/Zn SOD Cu, Zn-superoxide dismutase, GSH-Px glutathione peroxidase, MDA malondialdehyde, T-AOC total antioxidant capability