Grazed grass and other forage-based diets are more likely to lead to higher levels of greenhouse gas production, according to Dr Tim Snellling, a research scientist at Harper Adams’ University.
“Grass and silage-based diets encourage a microbial population in the rumen, which is more disposed to producing methane,” he said.
Research trials have confirmed a clear association between dietary fibre levels and methane production. In other words, the higher the concentrate fraction of the diet, the lower the potential for methane production.
Dr. Snelling said that methane is produced when carbon dioxide combines with hydrogen in the rumen.
He also confirmed that grazed grass is a perfectly natural feed for ruminant animals.
“But, from an environmental point of view, it’s a question of balance. Suckler cows grazing upland pastures, for example, bring a very positive environmental dimension to the way in which farmers manage their land. At a very fundamental level, the cows encourage a wide variety of grasses and other plants to grow, which help maintain and improve biodiversity.”
Dr. Snelling said that research is helping to identify inhibitors that can target the chemical pathways that lead to the production of methane in the rumen.
He said: “Nitrate is one such inhibitor that has already been identified. A number of plant oils also act as inhibitors, when it comes to the production of methane in the rumen.
Downsides to the use of these products include their cost and identifying the best way of including them in animal diets.
However, the good news for grassland farmers is that the objective of putting production agriculture on a ‘sustainable intensification’ footing can be achieved.
“We now know that improving the genetic merit of beef and dairy cattle can have a very beneficial impact on a farm’s carbon footprint,” confirmed Prof. Frank O’Mara, director of research at Teagasc, an agricultural research and development agency in the Republic of Ireland.
“The same can be said for improved grassland management practices.
The inclusion of clover in grass swards will also help to reduce greenhouse gas and ammonia production.
O Mara confirmed a number of important input options that can have a very significant impact on a farm’s carbon footprint value.
“The use of protected urea is a real game changer in this regard,” he stressed.
“Research has confirmed that this product can be used successfully on grassland throughout the growing season.”
