Table 3 Regression equations to estimate intake, digestibility, faecal N, and liveweight

Concentrate intake (kg DM/d)

Y = −2.39 + 0.0117(I) + 2.68(C) - 0.348(C²)

0.97

<0.0001

Guinea grass intake (kg DM/d)

Y = 0.701 + 0.00782(I) - 0.321(C)

0.69

0.0002

Rice straw intake (kg DM/d)

Y = 0.747 + 0.00539(I) - 0.00808(C) - 0.209(C²)

0.93

<0.0001

Substitution rate (kg DM/kg DM)

Y = 1.16 - 0.00589(I) + 0.215(C)

0.85

<0.0001

³OM intake (kg/day)

Y = −0.996 + 0.0227(I) + 2.30(C) - 0.535(C²)

0.95

<0.0001

⁴GE intake (MJ/d)

Y = −18.9 + 0.438(I) + 43.8(C) - 10.1(C²)

0.94

<0.0001

⁵CP intake (kg/d)

Y = −0.278 + 0.00307(I) + 0.407(C) - 0.0693(C²)

0.97

<0.0001

⁶EE intake (kg/d)

Y = −0.114 + 0.000818(I) + 0.144(C) - 0.0221(C²)

0.97

<0.0001

⁷NDF intake (kg/d)

Y = 1.27 + 0.00886(I) - 0.240(C)

0.48

0.0036

OM digestibility (%)

Y = 54.4 + 8.00(C)

0.84

<0.0001

Digestible OM intake (kg/d)

Y = −0.149 + 0.0106(I) 0.971(C)

0.88

<0.0001

Gross energy digestibility (%)

Y = 75.0 + 13.6(C) - 4.36(C²)

0.43

0.0086

Digestible energy intake (MJ/d)

Y = −7.39 + 0.311(I) + 38.5(C) - 8.75(C²)

0.89

<0.0001

CP digestibility (%)

Y = 56.9 + 6.09(C)

0.63

<0.0001

EE digestibility (%)

Y = 9.28 + 0.0884(I) + 38.8(C) - 7.62(C²)

0.93

<0.0001

NDF digestibility (%)

Y = 59.8 - 8.06(C)

0.63

<0.0001

Faecal N (kg/d)

Y = −0.00168 + 0.000129(I) + 0.0203(C) - 0.00589(C²)

0.89

<0.0001

Initial liveweight (kg)

n.a.

n.a.

0.9905

Final liveweight (kg)

Y = −13.7 + 1.12(I) + 64.9(C) - 15.6(C²)

0.97

<0.0001

Liveweight gain (kg/d)

Y = −163 + 1.43(I) + 773(C) - 185(C²)

0.90

<0.0001