Cows take antibiotic largest polluters

Study shows that drugs given to livestock worsen environmental damage by increasing the concentration of methane in burping, flatulence and cattle dung, the gas is known as responsible for the greenhouse effect.

                 

Antibiotics can increase methane released by cattle

The use of antibiotics in livestock may increase emissions of gases responsible for the greenhouse effect, says a recent study. In it, an international team of researchers finds that the action of antibacterial drugs in order to improve health and stimulate herd growth, has the potential to raise the methane level in intestinal gas and manure of cattle.

An "involuntary environmental effect cascade", as well as affecting cattle, the indiscriminate use of medicines in commercial livestock reaches the insects that feed on dung and may have "important consequences for human health and the environment."

The responsible for the research team is composed of scientists from the United States, United Kingdom, Finland and Sweden, led by Tobin Hammer, an expert on microorganisms at the University of Colorado. His report was published in the journal Proceedings of the Royal Society B.

The dung beetle to

Cattle manure provides nutrients, organic matter and miroorganismos for different ecosystems, but is also a source of pathogens and significant amounts of greenhouse gases, such as methane, nitrous oxide and carbon dioxide, remind researchers.

The use of antibacterial drugs in agriculture leads to antibiotic resistance problem classified as growing and urgent by the World Health Organization (WHO) and the pharmaceutical industry. The authors of the study also indicate the risk that favors "the development of antimicrobial resistance among pathogens and the spread of antibiotic genes in the surrounding environments."

It was also found that "antibiotics alter the structure and activity of the intestinal microbiota and [microbial community] of the fecal mammals." Directly or indirectly, so the drugs influence the emissions of greenhouse gases by cattle. It may also be affected the ability of insects to reduce the production of methane, with "some potential impacts on agricultural systems."

Tests and results

To test their theory, the scientists examined the animals treated or not with a broad-spectrum antibiotics. After analyzing the microbiota of cattle dung and manure-of-beetles collected in the fields, they have assessed the effects of antibiotics on the size and quantity of insects, and tested the greenhouse gases emitted by manure.

The international team found "clean effect" of antibiotic treatment on microbial communities that persisted for more than three weeks after defecation and collection. Although the size, reproduction and survival of beetles have not been compromised, your microbiota has changed.

The study confirms the role of beetles-of-manure to reduce methane flow: Previous studies have linked this effect to the resulting oxygenation of tunnels dug by the insects in the manure. Nevertheless, treatment with antibiotics "consistently increased methane emissions", as well as nitrous oxide. The carbon dioxide remained constant.

In their conclusion, the scientists emphasize "a unique feature of antibacterial drugs": "Although not directly toxic to animals which are not intended, antibiotics may have a range of unexpected effects." They suggest that there will be more comprehensive studies both on the correlation of manure and digestive cattle gases with emissions of greenhouse gases, and to evaluate "the global extent and purpose of the use of antibiotics in livestock."