Effects of diet forage source on methane emissions from dairy cattle


The farming of ruminant livestock is a major source of greenhouse gas emissions, including methane, which has 25 times greater global warming potential than carbon dioxide. Enteric methane not only contributes to greenhouse gas emissions, but also represents a substantial waste of feed energy for ruminant animals. Greater knowledge of factors that determine emissions could lead to reduced environmental effects and improvements in dietary energy utilisation for ruminant-derived food production. Several methane-mitigation opportunities have been identified, including changes in diet carbohydrate amount and type.


Research undertaken at the University of Reading has examined the effect of feeding forages differing in the proportions of maize silage and grass silage to lactating dairy cattle, which alters the proportions of dietary starch and fibre, on feed intake, milk production and composition and methane emission. This has aimed to test the hypothesis that feed intake and milk production would be greater and methane yield (g/kg of dry matter intake) and methane intensity (g/kg milk yield) lower for cows fed higher maize silage diets, compared with higher grass silage diets that have higher NDF concentrations.

Outcomes and Impact

The research concluded that changes in diet carbohydrate amount and type (i.e. starch vs. fibre) can affect ruminant methane emissions.

Cows fed higher maize silage diets had a greater dry matter intake, milk production and lower methane yield (g/kg of dry matter intake), compared with cows fed high grass silage diets.

Key university staff 

Professor Chris Reynolds , Professor of Animal & Dairy Science
Les Crompton, Senior Research Fellow, Animal Dairy & Food Chain Sciences
A.K. Jones, Head of Applied Unit, Animal Dairy & Food Chain Sciences
Paul Kirton, Research Technician, Animal Dairy & Food Chain Sciences
David Humphries, Head of Specialist Units, Animal Dairy & Food Chain Sciences

Related Publications

Effects of diet forage source and neutral detergent fiber content on milk production of dairy cattle and methane emissions determined using Green Feed and respiration chamber techniques

Effects of forage source and extruded linseed supplementation on methane emissions from growing dairy cattle of differing body weights

Methane emissions from cattle: estimates from short-term measurements using a Green Feed system compared with measurements obtained using respiration chambers or sulphur hexafluoride tracer

The inclusion of forage mixtures in the diet of growing dairy heifers: impacts on digestion, energy utilisation, and methane emissions