Overview of Products Obtained from Rendering Animal By-Products

Every year, the global meat industry processes billions of animals. Long after the cuts of meat leave the slaughterhouse, a significant portion of each animal – bones, fat, blood, and offal – still remains. Rather than treating this as waste, the rendering industry steps in to transform these materials into a range of commercially valuable products. Rendering is defined as any process that converts waste animal tissue into stable, usable materials – and the products it yields are far more varied and important than most people realize.

What happens during rendering 🔗

According to the USDA, the rendering process cuts and grinds accepted animal carcasses into small pieces, blends and cooks them, then separates the output into fat (lard and tallow), protein materials (meat and bone meal), and wastewater. The concentrated protein is dried, ground, and stored for shipment, while fats undergo additional purification before distribution.

Rendering can be carried out as either an edible or inedible process. Edible rendering is done at low temperatures in a continuous process, producing lard or edible tallow for use in food products. It is almost exclusively carried out by meat packing companies using USDA-inspected materials. Inedible rendering, on the other hand, processes materials unsuitable for human consumption – condemned offal, fallen stock, and non-food-grade tissues – and uses higher temperatures to ensure complete pathogen destruction. The two streams are kept entirely separate. Most of the inedible material is processed using the dry method, where grinding and heat drive off moisture and release fat from cells; the remaining solids, called cracklings, are further ground into meat and bone meal.

Tallow: rendered fat from cattle and sheep 🔗

Tallow is the rendered fat obtained from cattle and sheep. It is one of the most commercially significant outputs of the rendering process, and its applications extend well beyond the obvious. The fat obtained can be used as low-cost raw material in making grease, animal feed, soap, candles, biodiesel, and as a feedstock for the chemical industry. Tallow derived from beef waste is also an important raw material in the steel rolling industry, where it provides lubrication when compressing steel sheets.

Tallow in food and animal feed 🔗

Food-grade tallow serves as a cooking fat and an ingredient in various processed foods, valued for its high smoke point and flavor stability. In animal feed, tallow is well known for being one of the more palatable fat sources and is more shelf-stable than less saturated fats, requiring less antioxidant addition to achieve shelf-life goals. It also contains a small level of conjugated linoleic acid (CLA), which has attracted growing research interest for its potential health properties.

Tallow in industry, cosmetics, and biofuels 🔗

Higher grades of tallow feed into a wide range of industrial and consumer products. These include soap, lubricants, fatty acids for cosmetics, paints, plastics, and organic detergents. In the pharmaceutical and cosmetics sector, tallow’s moisturizing and emollient properties have made it a sought-after ingredient in skincare products, soaps, and ointments. One of its most rapidly growing uses today is as a feedstock for biodiesel production. Tallow serves as a reliable feedstock in transesterification, where it is converted into biodiesel – a renewable energy source with properties similar to petroleum-based diesel. Before this application was developed, much of this material was incinerated or sent to landfills, making the shift to biofuel use a meaningful sustainability gain.

The global tallow market reflects this growing industrial demand. The market was valued at USD 9.92 billion in 2025 and is projected to nearly double to USD 19.14 billion by 2034, growing at a CAGR of 7.55%, driven primarily by rising demand for biofuels, oleochemicals, and personal care products.

Lard: rendered fat from pigs 🔗

Lard is the rendered fat specifically produced from pigs. The process transforms pork fat into lard through edible rendering carried out at low temperature in a continuous process, with centrifugal separation used to isolate the fat. Lard shares many of tallow’s end-use applications but has a distinct fatty acid profile – it is comparatively less saturated than beef tallow, making it suitable for different formulations in both food and industry.

In culinary applications, lard has long been valued for producing flaky pastries, biscuits, and pie crusts, and it has a high smoke point that makes it effective for frying. Beyond cooking, lard is used in soap and cosmetic manufacturing, pharmaceutical preparations, and various industrial applications similar to those of tallow. Rendered fats including lard provide a supplementary source of energy, flavor, texture, and nutrients in pet food formulations, where they are almost universally incorporated alongside protein meals.

Meat and bone meal 🔗

Meat and bone meal (MBM) is the dry, granular protein product that remains after fat has been separated from the solid fractions during rendering. Blood, hides/skins, and bone meals are all prepared from meat waste by the rendering process, which consists of cooking, defatting, and grinding of meat waste to obtain two separate fractions – fat and flour. MBM is typically identified by its source species (e.g., poultry MBM, swine MBM, ruminant MBM) due to regulatory requirements that control cross-species feeding.

MBM in animal feed 🔗

MBM and similar animal by-product meals are valued primarily for their protein and amino acid content, and as a phosphorus source. The protein content of MBM typically ranges from 45 to 55%, and the product is rich in calcium and phosphorus – minerals that are otherwise costly to supplement separately. Pet food manufacturers rely on MBM to provide high-quality protein in dog and cat foods, while livestock feed formulations incorporate it where regulations permit. However, the feeding of ruminant-derived MBM to other ruminants is widely prohibited in most countries following the bovine spongiform encephalopathy (BSE) crisis of the late 20th century, which highlighted the risks of prion transmission through animal feed.

MBM as fertilizer and energy source 🔗

Where its use in feed is restricted, MBM finds an important secondary market as an organic fertilizer and for energy generation. Field studies comparing MBM to mineral fertilizers found that MBM applied at 1.5-2.0 tonnes per hectare supported grain yields and quality parameters matching or exceeding mineral fertilization, while also showing lower greenhouse gas emissions and acidification impacts. Power stations in several countries have also utilized MBM as a source of alternative renewable energy, burning it as a biomass fuel to generate electricity.

Blood meal 🔗

Blood meal is produced by collecting fresh blood at slaughter – primarily from cattle, pigs, and poultry – and then drying it through methods such as spray drying, drum drying, or flash drying. Blood can be collected during the slaughter of various livestock species under a wide range of conditions, and it is usually dried and made into blood meal so that it can be handled and incorporated into rations more easily. The resulting product is a dark reddish-brown powder that is among the most protein-dense feed ingredients available.

Blood meal in animal nutrition 🔗

Blood meal contains mostly protein – about 90-95% on a dry matter basis – and small amounts of fat and ash. Its lysine content is particularly high (7-10% DM), making it an excellent supplement to cereal-based and plant-based diets that are typically deficient in this essential amino acid. It has been shown to be a satisfactory replacement for other protein sources in diets for dairy cattle, beef cattle, sheep, pigs, poultry, and various fish species. In aquaculture, blood meal is a highly digestible protein that supports lean muscle growth, and its high iron content is particularly beneficial for preventing anemia in young animals. That said, blood meal is not very palatable, and its amino acid balance is not ideal on its own – it is low in isoleucine and methionine – so it is typically used as one component of a balanced feed formulation rather than a sole protein source.

Blood meal as organic fertilizer 🔗

Blood meal is a dry, inert powder used as a high-nitrogen organic fertilizer, and is one of the highest non-synthetic sources of nitrogen available. By weight, it typically contains 12-15% nitrogen, making it particularly effective for crops with high nitrogen demand such as corn, tomatoes, and leafy greens. Blood meal is one of the main fertilizers permitted in certified organic farming, and its nitrogen releases more gradually than synthetic sources, reducing the risk of nutrient burn while supporting sustained plant growth. When worked into soil, it also stimulates beneficial microbial activity, improving soil structure and nutrient cycling over time.

The sustainability argument for rendering 🔗

One of the most compelling reasons to understand rendering products is the environmental case for the industry. By recycling approximately 97 billion pounds of animal by-products annually in North America alone, rendering prevents landfill waste, reduces groundwater contamination from improper carcass disposal, and sequesters greenhouse gases at a net positive rate, contributing meaningfully to the sustainability of animal agriculture. Without rendering, the volumes of fat, bone, blood, and offal produced by abattoirs would overwhelm waste management systems and create serious environmental and public health hazards.

The rendering industry has also increasingly become part of the circular economy narrative. Livestock, aquaculture, and crop industries increasingly value rendered proteins and fats as sustainable alternatives to synthetic inputs or limited marine resources such as fish meal. Tallow-based biodiesel, MBM-based fertilizer, and blood meal as an organic nitrogen source all represent cases where animal by-products displace the need for virgin fossil fuel-derived or synthetically manufactured alternatives.

Effective rendering, in this sense, is not just a processing step – it is a system that closes the loop on one of agriculture’s largest material flows, ensuring that nearly every part of a slaughtered animal is converted into something useful.

What do you think? As consumer awareness of sustainability in food systems grows, should rendering products be more prominently labeled and promoted as environmentally responsible ingredients in feed and fertilizer? And given the strict regulations around feeding animal-derived meals back to ruminants, how should the industry balance the nutritional value of products like MBM against ongoing biosecurity concerns?

References

1. https://en.wikipedia.org/wiki/Rendering_(animal_products)
2. https://www.aphis.usda.gov/sites/default/files/7-rendering.pdf
3. http://assets.nationalrenderers.org/essential_rendering_pet_food.pdf
4. https://bakercommodities.com/products/tallow/
5. https://www.sciencedirect.com/article/abs/pii/S0959652617304985
6. https://straitsresearch.com/report/tallow-market
7. https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/bone-meal
8. https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/blood-meal
9. https://tg-machines.com/meat-rendering
10. https://www.feedipedia.org/node/221
11. https://www.feedingredientsasia.com/market-insights/blood-meal-vs-soy-fish-poultry-protein-comparison
12. https://en.wikipedia.org/wiki/Blood_meal
13. https://grokipedia.com/page/Rendering_(animal_products)
14. https://www.ibisworld.com/united-states/industry/rendering-meat-byproduct-processing/5787/