Amlan Kumar Patra
West Bengal University of Animal and Fishery Sciences
India
Title: Development of linear and non-linear statistical models for prediction of enteric methane emission from cattle in tropical production systems
Biography
Biography: Amlan Kumar Patra
Abstract
The objective of this study was to develop linear and nonlinear statistical models to predict enteric methane emission (EME) from cattle in the tropics based on dietary variables. A database from 35 publications, which included 142 mean observations of EME measured on 830 cattle, was constructed to develop EME prediction models. Several extant EME prediction equations developed for North-American and European cattle were also evaluated for suitability of those equations in this dataset. The simple linear equation that predicted EME with high precision and accuracy was methane (MJ/day) = 1.29(±0.906) + 0.878(±0.125) × dry matter intake (kg/day) (DMI) [RMSPE = 31.0% with 92% of mean square prediction error (MSPE) being random error; R2=0.70]. Multiple regression equations that predicted slightly better than simple prediction equations were methane (MJ/day) = 0.910(±0.746) + 1.472(±0.154) × DMI – 1.388(±0.451) × feeding level - 0.669(±0.338) × acid detergent fiber intake (g/kg); n = 91; RMSPE = 4.22 [RMSPE = 22.2%, with 99.6% of MSPE from random error; R2=0.84]. Among the nonlinear equations developed, Mitscherlich model [methane (MJ/day) = 71.47(±22.14.6) × (1 - exp{-0.0156(±0.0051) × DMI] performed better than simple linear and other nonlinear models, but the predictability and goodness of fits of the equation did not improve compared with the multiple regression models. Extant equations overestimated EME, and many extant models had low accuracy and precision. The equations developed in this study will be useful for improving national methane inventory preparation, and for a better understanding of dietary factors influencing EME for tropical cattle feeding systems.