Comparing Methods of Meat By-product Disposal

By Jessica Meisinger, Director of Education, Science, and Communication
Fats and Proteins Research Foundation

One of the most important aspects of research is getting it widely distributed so results can be read and applied. Being published in peer-reviewed journals is a key part of the process because it shows that the paper has been scrutinized and accepted by other scientists. Dr. Charles Gooding, formerly of Clemson University, and Dr. David Meeker of the Fats and Proteins Research Foundation (FPRF) have successfully published an instrumental paper in The Professional Animal Scientist titled, “Review: Comparison of 3 alternatives for large-scale processing of animal carcasses and meat by-products.” The article was chosen as the June 2016 issue’s “Editor’s Choice,” an honor given to a particularly noteworthy article in each volume. Due to this, the article is available online at no charge at until the next issue of the journal is released, giving it added exposure. As of mid-July, the article was the most read on the journal’s website.

The Professional Animal Scientist is the journal of the American Registry of Professional Animal Scientists, whose purpose is to provide certification of professional status for qualified members of the society, to strengthen animal sciences among the professions, and to promote animal sciences and the profession of animal scientists. Continual education is required of all certified professionals to keep abreast of rapidly changing technology in their fields.

“The Gooding/Meeker review article compares biosecurity, current environmental regulations, greenhouse gas emissions, and effective resource recovery as considerations when deciding among anaerobic digestion, composting, and rendering as alternative methods for disposal of animal carcasses and meat by-products,” said The Professional Animal Scientist. “It addresses aspects of current societal concerns about food animal processing.”

The journal article shows that rendering has several advantages over composting and anaerobic digestion for effective handling of large quantities of meat by-products. All three methods work but rendering is the best choice for a number of reasons. One is biosecurity. Both anaerobic digestion and industrial composting are undeveloped industries that are not well regulated. Regulations vary from state to state and there is no consistent federal regulation on air emissions or wastewater for anaerobic digestion and composting as there is for rendering.

Seepage and leachate from anaerobic digestion and composting could contaminate groundwater and potentially harm people, animals, and plants. Both industrial composting and anaerobic digestion require strict parameters to be followed to destroy pathogens and if this process is not controlled, pathogen and environmental problems increase drastically. Rendering is a mature industry that is regulated both by states and the federal government though the Food and Drug Administration, Environmental Protection Agency, and United States Department of Agriculture.

Greenhouse gas production is another area where rendering is a clear winner in the article’s analysis. Decomposition of meat by-products in industrial compost, landfills, or in fields would emit about five times as much greenhouse gas as the fuel used in the rendering process does. Depending on economics, renderers also use the fat produced from the rendering process to fuel their boilers, lessening dependence on outside fuel sources. Rendering retains almost all carbon so it does not become carbon dioxide or methane. As Gooding and Meeker presented in the article, industrial composting has low energy requirements yet about half to three quarters of the carbon is released as carbon dioxide with up to 20 percent of the carbon being released as methane, which has 25 times the global warming potential of carbon dioxide. Although anaerobic digestion also has low energy requirements, if the digestate slurry is stored in open tanks, the greenhouse gas emissions can increase tenfold.

Finally, the article states that end products of the rendering process are valuable. About 99 percent of meat and meat by-products rendered are recycled into ingredients for animal feed (including aquaculture) and pet food as well as biofuel, fertilizer, and industrial and consumer products. The economic value of these end products is at least three times the value of end products from anaerobic digestion (fertilizer and methane fuel gas) and five times that of industrial composting (fertilizer).

There were some challenges in getting this article published.

“The primary challenge was finding the most appropriate journal,” said Gooding. “We contacted two journals that have broad scopes of interest related to waste management and recycling. They seemed to prefer papers that contain data-intensive studies on a particular process or comparison of alternatives. In the end I think we found the best journal as The Professional Animal Scientist has high scientific standards and its readers are people who have the most at stake in the issues covered by the article.”

The article is at

August 2016 RENDER | back