Link between farming and global warming

Holstein cows in the barn [iStockphoto]

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

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

Livestock as a source of greenhouse gases

Cattle have entered the global warming debate because of the third gas – methane. Livestock is the main source of methane production. The amount of methane emitted depends on the number of animals, the type of digestive system and the amount of food consumed. Ruminants, namely cattle, sheep, goats and camels, are the biggest producers of methane. They do this through methanogens – microbes that digest food and emit methane as a byproduct (enteric fermentation).

How can farmers reduce greenhouse gas emissions from livestock?

While livestock are a major emitter of methane, reducing their numbers will appear to be a good strategy. But this will counteract the great role livestock play in ensuring food security and may not be practical. For this reason, measures to reduce greenhouse gas emissions should modify enteric fermentation to reduce emissions while increasing livestock productivity by increasing digestive efficiency. Raising animals with the right diet and dietary supplements can help reduce methane emissions. Research shows that there are animal breeds that emit relatively little methane (methanogenesis) per unit of food absorption capacity. Research on animal husbandry shows promising results when it comes to methane production. The data shows that it is possible to achieve up to 20% methane reduction. Now, no farmer will buy such a breed if that is the only benefit he will get; so if this breed improvement can be linked to increased feed conversion efficiency and therefore better production, it may be a good selling point.

A number of dietary supplements and dietary alternatives are being researched in hopes of helping to reduce greenhouse gases by manipulating enteric fermentation. They include oils, certain plants with natural steroids, fats, probiotics, nitrates, enzymes, sea algae. Improved pastures are closely linked to feed supplements and feed alternatives. Good pastures are low in fiber and easy to digest. Fiber-rich foods ferment slowly and therefore produce more methane per unit of food digested. More leguminous feeds when mixed with other feeds will improve the diet of animals, increase their growth rate and productivity and further reduce greenhouse gas emissions.

Good breeding has the effect of reducing greenhouse gas emissions. It has 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]

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