Table 7 Multiple regression analysis to choose the most important protein spectral parameters to predict protein ruminal digestion of CP
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 |
|---|---|---|---|---|---|
Degradation kinetics of CPb | |||||
Kd, %/h | Amide I area, α-helix height | Y = 21.70–2.33 × Amide I area – 100.29 × α-helix height | 0.46 | 1.808 | < 0.01 |
S, g/kg | Amide II height, Amide II area | Y = 1.57 + 399.24 × Amide II height – 6.05 × Amide II area | 0.51 | 2.050 | < 0.01 |
D, g/kg | Amide I height, β-sheet height | Y = 65.67–199.00 × Amide I height + 213.44 × β-sheet height | 0.42 | 3.202 | < 0.01 |
U, g/kg | Amide area, α-helix height | Y = 30.82 + 3.87 × Amide area − 364.64 × α-helix height | 0.62 | 3.252 | < 0.01 |
BCP, g/kg DM | Amide I, II ratio | Y = − 132.49 + 14,247 × Amide I, II ratio | 0.34 | 28.925 | < 0.01 |
EDCP, g/kg DM | Amide I height, β-sheet height | Y = 125.35–827.29 × Amide I height – 1187.03 × β-sheet height | 0.67 | 13.537 | < 0.01 |
Intestinal digestibility of CPc | |||||
dIDP, g/kg CP | Amide II height, Amide II area | Y = 102.68–749.79× Amide II height + 11.50 × Amide II area | 0.48 | 4.055 | < 0.01 |
IDP, g/kg | Amide I, II ratio, Amide area, β-sheet height, α, β- ratio | Y = 113.54 + 19.77 × Amide I, II ratio + 6.73 × Amide area − 571.92 × β-sheet height–117.54 × α, β- ratio | 0.90 | 2.149 | < 0.01 |
Total tract– digestibility of CPd | |||||
TDP, g/kg DM | Amide I area, α-helix height | Y = 42.01 + 37.43 × Amide I area – 1282.98 × α-helix height | 0.76 | 16.705 | < 0.01 |