Abstract

Ruminant livestock produce at least 75% of New Zealand’s total methane emissions and are a major contributor of greenhouse gas emissions. Most ruminant methane arises from microbial activity in the rumen (methanogenesis) and is released through the mouth and nose. Methane production per unit feed intake or per unit production can be reduced by improving diet quality, for example, including legumes in a pasture diet. A preliminary investigation with wether sheep showed lower daily methane outputs per unit dry matter intake (DMI) when fed Lotus pedunculatus (a condensed tannin-containing legume) than ryegrass-based pasture or lucerne (14.5 vs. 20.4 vs. 19.0 gCH4/kg DMI). Friesian dairy cows fed either Lotus corniculatus silage or perennial ryegrass silage had similar total methane outputs (376.7 vs. 344.4 g CH4/cow/day; ns). However, methane emissions were lower from cows fed Lotus silage when expressed per unit DMI (26.90 vs. 35.13 g CH4/kg DMI; P<0.001) and per unit production (378 vs. 434 g CH4/kg milksolids; P<0.05) as a result of the higher intake and milksolids yield. The mitigation of methane emissions from animals fed Lotus species was due in part to a higher nutritive value relative to pasture but effects of condensed tannins on methanogenesis warrants further investigation.

SL, Woodward, GC Waghorn, MJ Ulyatt, and KR Lassey

Proceedings of the New Zealand Society of Animal Production, Volume 61, Christchurch, 23-26, 2001