Table 6 Multiple regression analysis to choose the most important spectral parameters to predict protein profile and energy profile
Predicted variable, Y | Variable selection (variables left in the model with P < 0.05) | Equation prediction: Y = a + b1 × x1 + b2 × x2 + … … . | Model R2 | RSDa | P value |
|---|---|---|---|---|---|
Basic protein profileb | |||||
CP, g/kg DM | Amide I area, α-helix height | Y = 4.19 + 4.12 × Amide I area – 137.95 × α-helix height | 0.73 | 2.048 | < 0.01 |
NDICP, g/kg CP | Amide I, II ratio | Y = −17.26 + 13.27 × Amide I, II ratio | 0.27 | 3.304 | 0.04 |
ADICP, g/kg CP | Amide II height | Y = −2.65 + 35.84 × Amide II height | 0.32 | 0.792 | 0.02 |
NPN, g/kg CP | Amide I, II ratio, Amide I area | Y = 93.01–10.83 × Amide I, II ratio – 1.95 × Amide I area | 0.78 | 2.081 | < 0.01 |
Predicted energy values by NRC, 2001c | |||||
tdCP, g/kg DM | Amide I area, α-helix height | Y = 4.47 + 4.21 × Amide I area – 145.52 × α-helix height | 0.73 | 2.137 | < 0.01 |
TDN1×, g/kg DM | Amide I height, β-sheet height | Y = 72.96 + 241.16 × Amide I height – 228.54 × β-sheet height | 0.81 | 1.301 | < 0.01 |
Protein subfractions, CNCPS 6.5d | |||||
PB2, g/kg CP | Amide II height | Y = 30.35–164.28 × Amide II height | 0.27 | 4.053 | 0.04 |
PC, g/kg CP | Amide II height | Y = −2.65 + 35.84 × Amide II height | 0.32 | 0.792 | 0.02 |