Development and evaluation of prediction equations for methane emission from Nellore cattle

Abstract

Dry matter intake (DMI), nutrient intake and enteric CH 4 emission were evaluated in 48 Nellore cattle (392 ± 27 days of age). Equations were generated from intake data and evaluated using root mean square prediction error (RMSPE), and validated by cross-validation. Equations that included DMI and hemicellulose intake (HEMI) [CH 4 (MJ d -1 ) =4.08(±1.65) + 11.6(±2.34)DMI(kg d -1 ) − 33.4(±7.21)HEMI(kg d -1 )]; DMI and total carbohydrate intake (TCHI) [CH 4 (MJ d -1 ) =5.26(±1.69) −6.3(±1.47)DMI(kg d -1 ) + 8.8(±1.81)TCI(kg d -1 )]; metabolizable energy intake (MEI) and cellulose intake (CELI) [CH 4 (MJ d -1 ) =5.16(±1.72) −0.13(±0.048)MEI(MJ d -1 ) +7.37(±1.53)CELI(kg d -1 )], and non-fiber carbohydrate intake (NFCI) [CH 4 (MJ d -1 ) =3.14(±1.48) +3.65(±1.05)NFCI(kg d -1 )] resulted in the lowest RMSPE (14.3, 14.1, 14.3 and 14.7%, respectively). When literature equations were evaluated using our database, the most accurate predictions were obtained with equations that included DMI and lignin intake (RMSPE = 15.27%) and MEI, acid detergent fiber intake and lignin intake (RMSPE = 15.7%). The mean error of predicting enteric CH 4 emission with the equations developed in this study based on DMI and nutrient intake is 17% and the most accurate predictions are obtained with equations including DMI, carbohydrate intake and MEI.