June 21, 2018

Feeding microbes to livestock could reduce environment impact, study says
 

Deforestation, agricultural greenhouse gas emissions and nitrogen losses from croplands could be reduced by more than 5% worldwide if 2% of animal feed are replaced with protein-rich microbes, a new study published in the Environmental Science & Technology journal found.

The research estimated the economic and environmental potential of feeding  microbial protein to pigs, cattle and chicken on a global scale.

According to Benjamin Leon Bodirsky, author of the study by the Potsdam Institute for Climate Impact Research, chickens, pigs and cattle consume about "half of the protein feed cultivated on global croplands."

He added that microbes can help avert further deforestation, biodiversity loss, nutrient pollution, and climate-impacting emissions which result from increased food and animal feed demand.

"Microbes can be cultivated with energy, nitrogen and carbon in industrial facilities to produce protein powders, which (instead of soybeans) are then fed to animals. Cultivating feed protein in labs instead of using croplands might be able to mitigate some environmental and climatic impacts of feed production. And our study expects that microbial protein will emerge even without policy support, as it is indeed economically profitable," Bodirsky explained.

Using computer simulations, the study examined the economic potential and environmental impact of microbial protein production until the middle of the century. It was found that between 175-307 million tonnes of microbial protein could replace conventional concentrate feed like soybeans worldwide.

By replacing about 2% of livestock feed with microbes, there will be reductions of 7% and 8% in agricultural greenhouse gas emissions and global nitrogen losses, respectively, as well as cutting by 6% the amount of  global cropland area used, the study stated.

"In practice, breeding microbes like bacteria, yeast, fungi or algae could substitute protein-rich crops like soybeans and cereals. This method was originally developed during the Cold War for space travel and uses energy, carbon and nitrogen fertilisers to grow protein-rich microbes in the lab," Ilje Pikaar from the University of Queensland in Australia said.

In the study, the researchers considered five different ways to breed microbes.

By using natural gas or hydrogen, feed production could be completely decoupled from cultivating cropland. This landless production avoids any pollution due to agricultural production. However, it also comes with a huge energy demand. Other processes that make use of photosynthesis by upgrading sugar, biogas or syngas from the agricultural origin to high-value protein result in lower environmental benefits. Some of these processes even cause an increase in nitrogen pollution and greenhouse gas emissions.

"Feeding microbial protein would not affect livestock productivity," Isabelle Weindl, one of the study's author, said.

"In contrast, it could even have positive effects on animal growth performance or milk production."

Still, even if it is economically profitable, the adoption of this new technology might face constraints such as habitual factors in farm management, risk-aversion towards new technologies, or lacking market access.

"Pricing environmental damages in the agricultural sector could make this technology even more economically competitive," Weindl said.

"Our findings clearly highlight that the switch to microbial protein alone will not be enough for sustainably transforming our agriculture," the study's co-author, Alexander Popp, commented.

To reduce the environmental impact on the food supply chain, major structural changes in the agro-food system are required, together with a shift of human dietary patterns towards more vegetables.

"For our environment and the climate as well as our own health, it might actually be another considerable option to reduce or even skip the livestock ingredient in the food supply chain. After further advances in technology, microbial protein could also become a direct part of the human diet - using space food for people's own nutrition."
 

- Potsdam Institute for Climate Impact Research