Unused hides, leather and the rendering industry

unused-hides-leather-and-the-rendering-industry

People eat meat and, as a result, we have many by-products on our hands. We can use these by-products for various applications, such as tanning hides/skins for leather and rendering (recycling) other products not fit for human consumption. Yet, the utilisation of these animal by-products is decreasing, as more and more people buy into synthetic alternatives. However, the irony is, meat consumption is increasing. What does that mean? It leaves us with immense amounts of (organic) leftovers and if we look at our global consumption levels, simply disposing of them is not a sustainable option; however, this is the unfortunate truth.

Waste from food production
Meat production results in lots of by-products, often over 40% of the animal, depending on the location (however, it can be over 50% for cattle). These by-products include waste from preparation and processing, and rendering of meat and other animal foodstuffs (e.g., bones, tendons, skin, internal organs and blood) to obtain fats and proteins. Utilising these by-products is essential for preventing this material from ending up in the environment. Why? Let’s look at some numbers.

Rendering numbers in the EU (annually):

  • Slaughtered:
    • 218 million pigs, sheep, goats, beef, and dairy cattle 
    • 6 billion chicken, turkey, and other poultry
  • Fallen stock:
    • 2.45 million tons collected*

*Fallen stock is collected from the farms within 24 hours for health & safety reasons.

That’s a lot of potential waste so it makes sense to re-use it if possible. However, not everything can be re-used. The Animal By-products regulations define what is and isn’t safe – and any material containing dangerous bacteria or fungi will not be used.

The rendering industry explained
Rendering is performed through heating, which dehydrates, sterilizes, and separates the animal by-products into fat, protein (including collagen and processed proteins fit for human consumption at the point of slaughter), meat and bone meal. The by-products are categorised according to the source of the material as part of the Animal By-products Regulations. These categories set limits on how the by-products can be treated or re-used.

  • Category 1: Any animal by products that contain infections or disease are classed as Category 1 and must be incinerated according to the legislation. This means that they cannot and will not be made into by products, and any risk they pose is dealt with through the requirements. Such materials include carcasses, materials suspected/confirmed of being infected with Bovine Spongiform Encephalopathy (BSE), materials containing prohibited substances, or specific risk material (SRM) generated from floor waste. 
  • Category 2: On-farm deceased animals, manure, digestive tract content or by-products of animals exceeding levels of certain substances (e.g., therapeutic drugs). 
  • Category 3: Material previously fit for human consumption (e.g., catering waste) or material currently fit for human consumption, but not intended for due to economic reasons, problems of manufacturing or packaging defects. Category 3 material also includes animal by-products derived from processing products for human consumptions and blood from healthy ruminants.

Examples of rendering products we use

  • Rendered products in food: collagen is used for gelatine, dried beef fat is used in cake mixes, bones are used to make broth. Fat is used for frying (like tallow), pork cracklings and edible fats in bakery products (e.g., croissants & pastries).
  • Rendered products in feed: feather, skin & bone meals in animal and aqua feed. Proteins in animal feed, but also phosphorous as fertilizer.
  • Rendered products in fuel: meat and bone meal are used for fuelling power stations but also transformed into biofuels and bioliquids. Tallow is also used as fuel.


Fact: Animal by-products provide enough phosphorous to fertilize 21,420 km2, which is about 20 times the size of Luxembourg.

There are many other applications for rendered by-products. Tallow can also be used to grease machinery, whereas other by-products can be reused in printing, skincare and healthcare (e.g., the lubricant on condoms). Animal by-product rendering is about making much of our lifestyle possible.

A strictly regulated industry
Rendering of by-products is something that most consumers are not aware of or do not like to concern themselves with. However, none of the above rendering products should alarm you or be cause for concern. The rendering industry and the categorization of its products are tightly regulated and bound by many rules.

Rendering involves either processing or incineration. For example, the dangerous materials in category 1 are used as fuel for incineration. Only low-risk materials are processed into products we actually use, and even then, processing lines of different categories and species are strictly separated. For example, bone meal, of bovine origin, cannot be processed into a bovine feed and, therefore, bone meal from terrestrial animals is often used in aquafeed instead. There is ethical reasoning behind this species separation; however, it is also due to the risk of diseases associated with cannibalism. This type of regulation tells you a lot about the ethical standards and care inherent to this industry.

What if we stopped using leather?
The hide makes up a significant amount (approximately 7%) of the total animal weight; however, the hide's value has dropped significantly due to availability excess. What could we do with the hides/skins if we didn't use them as leather? The only real solution for leather would be rendering, as hides and skins are rich in collagen, a highly useful resource, particularly in skincare products. Hides/skins fall into category 1 by-product (unless the animal was diseased), which means they are fit for use in food, feed and other applications. However, the question is, what would happen with such an abundant amount of additional waste as the demand for animal by-products is dropping. The irony remains, that people opt to use fewer animal by-products in other applications but eat more meat (thus perpetuating a cycle where we have more waste from the food industry and produce plastic non-degradable alternatives)—a great cause for concern.

Rendering of by-products is part of the animal's full lifecycle, which starts at the farm (and is also changing with the emergence of regenerative practices). It is a sign of respect to use everything and not just let it go to waste. The sustainability alliance believes rendering of by-products and leather production are both involved in reducing waste. Plastics are not the solution for a lower environmental impact. These industries embody the original recycling principles. After all, there should be 4 R’s in the adage: reduce, reuse, recycle, render -and of course, leather fits right into the same principle.




Reference And Sources Used
  1. Meeker, D. (2006) An overview of the rendering industry. Fats and Proteins Research Foundation. Retrieved from: ResearchGate. [Accessed on 5 November 2020]
  2. Jayathilakan, K., Sultana, K., Radhakrishna, K. et al. (2012) Utilization of by-products and waste materials from meat, poultry and fish processing industries: a review. J Food Sci Technol 49, 278–293. https://doi.org/10.1007/s13197-011-0290-7 
  3. Cummins,E. Curran, T. (2014). Biosystems Engineering Research Review 19. Retrieved from: ResearchGate. [Accessed on 5 November 2020]
  4. EFPRA, Glossary for the animal by-product processing sector. Retrieved from: EFPRA [Accessed on 5 November 2020]
  5. Consolidated text: Regulation (EC) No 1069/2009 of the European Parliament and of the Council of 21 October 2009 laying down health rules as regards animal by-products and derived products not intended for human consumption and repealing Regulation (EC) No 1774/2002 (Animal by-products Regulation). Retrieved from: EUR-Lex [Accessed on 5 November 2020]
  6. Haug, I., Draget, K. (2011) Handbook of Food Proteins. Woodhead Publishing Series in Food Science, Technology & Nutrition
  7. Zane, P (1996) It ain’t just for meat; it’s for lotion. New York Times. Retrieved from: New York Times. [Accessed on 5 November 2020]
  8. The Sustainability Alliance (2020) Rendering and Leather Reduce Environmental Impact. Retrieved from: The Sustainability Alliance. [Accessed on 5 November 2020]