Effects of forage chicory (Cichorium intybus) and perennial ryegrass (Lolium perenne) on methane emissions in vitro and from sheep

Abstract

Published reports of CH4 yields as g CH4/kg dry matter (DM) intake suggest that emissions from sheep fed fresh forage chicory (Cichorium intybus) are about 30% lower than from those fed fresh ryegrass. In this study, 2 year old wethers (16; 54±3.8kg liveweight) were fed either mature chicory or perennial ryegrass at 1.3 times maintenance metabolisable energy requirements in the late spring/early summer of 2009. Methane emissions were determined using individual animal respiration chambers. Feeds differed in their chemical composition with chicory containing 856g/kg organic matter (OM), 117g/kg crude protein (CP) and 281g/kg neutral detergent fibre (aNDF), whereas ryegrass contained 916g/kg OM, 85g/kg CP and 499g/kg aNDF. The DM intake was similar for both forages at 0.76kg/d, and CH4 yields did not differ between forages being 22.8 and 23.8g CH4/kg DM intake for chicory and ryegrass, respectively. In vitro incubations of chicory and perennial ryegrass in the vegetative or mature states had similar CH4 yields. Despite large differences in chemical composition, especially aNDF, chicory and ryegrass had similar CH4 yields in vitro and in vivo. Chicory is not a viable alternative to perennial ryegrass for mitigating CH4 in pastoral based sheep production systems.This paper is part of the special issue entitled: Greenhouse Gases in Animal Agriculture – Finding a Balance between Food and Emissions, Guest Edited by T.A. McAllister, Section Guest Editors: K.A. Beauchemin, X. Hao, S. McGinn and Editor for Animal Feed Science and Technology, P.H. Robinson.