Greenhouse gas
Cattle have four stomachs to help them digest the grasses they eat. The first stomach, called the rumen, holds grass that is only partly chewed – this is called the ‘cud’. They keep the cud in the rumen, then burp it up and chew it again before digesting it – and that’s known as ‘chewing the cud’. When they bring the cud up they emit methane, a greenhouse gas, from their rumen.
Other animals that are ruminants include: camels, giraffes, bison, deer, alpacas, yaks, wildebeests, llamas, buffalo, water buffalo and antelopes.
Unlike many other countries, in Australia cattle generally graze on extensive, natural pastures which help to capture carbon dioxide, a greenhouse gas. The transfer of carbon in the environment is part of a natural process.
Cattle in the carbon cycle
The carbon stored in plants is consumed by livestock when they graze. Some carbon is then released into the atmosphere (as carbon dioxide as the animals breathe and methane as they digest their food). Carbon dioxide is then re-absorbed by plants as they grow and so the cycle continues.
Carbon sequestration
Carbon is absorbed from the atmosphere by plants as they grow. Some of this carbon is stored in the leaves, stems and roots of plants and some is stored in the soil, improving the soil’s health. The process of absorbing carbon from the atmosphere and storing it in plants and soil is called ‘sequestration’.
Deep-rooted perennial pastures and trees found in grazing systems in Australia are an important carbon sink.
Efforts to reduce greenhouse gases
Methane emissions vary depending on the animal’s diet and size. A key to reducing emissions is by maximizing the animal’s growth rate and converting as much of this ‘lost energy’ into meat. This can be achieved through breeding animals that convert their feed more efficiently and improving feed management.
From 1990 to 2006, greenhouse gas emissions from cattle and sheep have reduced by 7% thanks to improved management practices and production efficiencies and changes in livestock numbers. In addition, production efficiencies have delivered at least a 12% reduction in emissions per tonne of beef produced.
Research to find further improvements is continuing.
Also read more on: