Prediction and evaluation of methane emission of growing cattle diets in Vietnam based on fecal near infrared reflectance spectroscopy

Tran Hiep, Dang Vu Hoa*, Vu Chi Cuong* and Nguyen Xuan Trach

Faculty of Animal Sciences and Aquaculture – Hanoi University of Agriculture - Vietnam
* National Institut of Animal Sciences – Hanoi - Vietnam

 

Abstract

The objective of the study was to estimate methane emission based on growing cattle diet intake and to develop prediction model for methane emission based on fecal NIRS that can be applied in practice. An experiment was carried out during 6 months (February – September) in the experimental station of Natianal Institute of Animal Sciences (Vietnam). Five growing cattle were used in a 5 x 5 Latin square (5 diets x 5 periods) design and fed 5 diets based on main forages and by-products in northern Vietnam (NaOH treated rice straw, napier grass, cassava leaf, cassava root meal, cotton cake and molasses). Feed intake was collected to estimate methane emission using an equation developed by Moe and Tyrell (1980). Fecal samples were scanned twice by a Foss NIRsystem 5000 monochromator to collect spectra. Methane-fecal pair database were than used to perform different mathematical techniques in WinISI software to select best model for methane prediction.

Results showed that methane emission efficiency (L/kg DMI) was negative correlated to DMI intake (figure 1). Methane production were positively correlated with NDF (r = 0,75) and ADF (0,69) but negatively correlated with ME concentration (r = - 0,34), CP content (r = - 0,40) and ADL content ( r = - 0,14). As a consequence, methane emission efficiency seemed to be highest with diet containing cassava leaf plus molasses (49.32 L/kg DMI) but lowest with diet containing only napier grass (63,18 L/kg DMI). It was also shown that the energy loss from methane emission was about 12.69%. Concerning NIRS analyze of feces, methane prediction equation obtained low and acceptable R². Thus, fecal NIRS represent an alternative promising method for estimating methane production in growing cattle.

Keywords: Fecal NIRS, methane emission, growing cattle.