Link between livestock and global warming

Holstein cows in the barn [iStockphoto]

Dear Daktari, I was recently reading some reports on global warming. I was shocked that livestock and especially cattle contribute to it through belching which produces methane. Is there anything that can be done to help cows emit less methane? [Josephat Ambunya, Vihiga County]

Dear Ambunya, yes livestock are the major sources of methane; one of the greenhouse gases. This is produced during fermentation. Gases that trap heat in the atmosphere are called greenhouses gases, resulting in an increase in atmospheric temperatures. The main greenhouses gases include carbon dioxide, methane and nitrous oxide. Carbon dioxide and nitrous oxide mainly come from burning fossil fuels like coal, natural gas and oil, solid waste. Carbon dioxide is absorbed/sequestered from atmosphere by plants.

Livestock as sources of greenhouse gases

Livestock have come into global warming debate due to the third gas - methane. Livestock are the dominant sources of producers of methane. The amount of methane emitted depends on number of animals, type of digestive system and amount of food consumed. Ruminants namely cattle, sheep, goats and camels are the greatest producers of methane. They do this through methanogens – microbes that digest feeds and emit methane as a by-product (enteric fermentation).

How can farmers reduce livestock emission of greenhouses gases?

While livestock are major emitters of methane, reducing their number will look like a good strategy. But this will counter the great role livestock play in ensuring food security and may not be practical. For this reason, measures to reduce greenhouse gas emission should change enteric fermentation to reduce emissions while also increasing livestock productivity by increasing digestive efficiency. Animal husbandry through good feeding and feed supplement can help reduce methane emissions. Research is showing that there are animal breeds that have a relatively low methane emission (methanogenesis) per unit feed intake ability. Research into animal breeding is showing promising results in as far as methane production is concerned. Data shows that can up to 20 per cent of methane reduction can be achieved. Now no farmer will buy such a breed if that is the only advantage they will get; so if this breed improvement can be tied to increased feed conversion efficiency and hence better production can be a good selling point.

A number of dietary supplements and feed alternatives are being considered in the hope of helping in reductions of greenhouse gases by manipulating enteric fermentation. They include oils, some plants with natural steroids, fats, probiotics, nitrates, enzymes, marine algae. Closely related to dietary supplements and feed alternatives is improved pastures. Good pastures have low fibre and are easily digestible. High fibre feeds ferment slowly and hence yield more methane per unit of feed digested. More leguminous feeds when mixed with other feeds will improve animal diet, increase their growth rate and productivity and additionally reduce greenhouse gas emissions.

Good animal husbandry has the effect of reducing greenhouse emissions. It comes with the advantage of increased production and productivity.

 [Dr Othieno is a veterinary surgeon and the head of communications at the Food and Agriculture Organization of the United Nations (FAO) Kenya. The views expressed here are not necessarily those of FAO]