Factors responsible for methane emission from cattle manure representing di
verse climates, systems and functions of cattle production are presented. T
hese factors were obtained by means of an experimental methodology develope
d for this project. It was considered that the temperature, moisture, handl
ing of manure and the animals' feed ration affect methane production. Dryin
g conditions and fermentation of manure in cool, temperate and warm climate
s were simulated in the laboratory. Cattle manure was obtained from animals
in intensive, semi-intensive and extensive production systems; for dairy,
non-dairy and double purpose cattle production functions. Also handling of
manure in dry lot, pasture and solid storage was considered. Results sugges
t that the dominant factor in methane emissions is the feed ration, followe
d by fermentation temperature and the excreta moisture content. The emissio
n factors obtained in this work are at least a factor of five smaller than
those proposed in the revised 1996 IPCC Guidelines for National Greenhouse
Gas Inventories for countries like Mexico. (C) 2001 Elsevier Science Ltd. A
ll rights reserved.