HomeArticlesInside Our Food Animals are more than just the cuts of meat we see in supermarkets. Like humans, they have hearts, lungs, livers and other organs, skin, spinal columns, feet, heads, and hair. But what happens to these parts when an animal is slaughtered for human consumption? After an animal is slaughtered and processed, butchers are left with the hot carcass - the weight of the unchilled carcass after the head, hide and internal organs have been removed, but with bones and fat still attached - and a range of edible by-products.1 In the EU and UK, animal by-products (ABPs) are defined as the parts of the animal not intended for human consumption.2,3 However, the US uses another definition for “edible by-products” - the parts of the animal that (often) do not end up in the conventional food system but are still edible, such as livers, hearts, tongues, tails, kidneys, brains, tripe, lips, fats, blood and certain bones.4In the EU and UK, these edible by-products are removed before what’s left is described as ABP, but it is these edible by-products, the ones with alternative uses, that are potentially being wasted. These products are repurposed in various ways: used for education, medicine, sweets, sports equipment, fireworks, candles, plastics, batteries, toiletries, make up, clothes, furniture, or even in cars. They can be rendered into fertiliser; ground for construction materials or coffee cups, or transformed into biogas. But some edible by-products are not being used - they are being wasted. So, what’s happening in our food system that means we’re wasting these resources? How did we get here?As global demand for meat and dairy has surged over the last 50 years, meat production has more than tripled with over 350 million tonnes produced annually. And so too has the production of by-products.5 In the EU alone, more than 20 million tonnes of animal by-products are now produced each year from slaughterhouses, industries producing food for human consumption, and fallen stock from farms.6While the ratio of meat to by-products varies among individual animals, typically around 12% of cattle live weight (how much the animal weighs while it is alive) and about 14% from pigs are edible by-products.4 In the past, both the industry and butchers found ways to make use of what remained after the prime cuts were taken. However, today smaller producers are being squeezed out by industry giants. Large-scale slaughterhouses, like Danish Crown—which processes around 16.6 million animals annually—benefit from economies of scale. They have better access to international markets and can sell by-products at lower prices than small abattoirs, often exporting them to distant markets like China or Taiwan. Meanwhile, small abattoirs like Perrys in Eccleshall, UK, face a different reality. With by-product prices plummeting and smaller quantities less attractive to buyers, they often have to pay for these by-products to be removed and incinerated. Stephen Hill of Perrys in Eccleshall told FoodUnfolded: “My small abattoir used to earn €176, maybe €188 a week by selling bones and fat. For hides we’d get €32-52 and for sheepskins probably about €10. Now we get paid nothing for these products and have to pay to have them taken away. By-products are a cost to us small abattoirs where once they earned us enough to cover a wage.”Read more: Small Abattoirs are Closing Fast - Why Does That Matter?How are animal by-products used?While animal by-products probably aren’t as visibly valuable as a premium cut at a local butcher, they hold significant value to a wide range of other industries.Clothes, furniture and cars: hides to leatherHides and skins are some of the most recognizable animal by-products that have an everyday use, commonly used to produce leather for clothing, sports equipment, furniture and car interiors. After animals are slaughtered, they are typically flayed (or skinned), and the hides are sent to tanneries for processing before being sold on to companies that manufacture leather products.Some large-scale companies, like Danish Crown, have their own in-house tanneries, Pedersen told FoodUnfolded.7 However, other industry leaders may “sell their hides to tanning companies” Pederson adds, “in some cases selling to tanning units run by their competitors”. By comparison, small abattoirs like Perrys of Eccleshall often struggle to sell their hides and skins. Due to the challenge of selling small quantities at a fair price, these by-products are sometimes incinerated, with abattoirs even paying hauliers to remove them.Sheep shearing in Usingen, Germany. A significant amount of sheep wool is burnt in Europe because it's not deemed good enough for fabric production. Photo via Getty.Medicine and education: organs for health and learningSeveral animal organs have medicinal uses. For example, insulin, which is used by some diabetics as an alternative to synthetic insulin, is extracted from a pig’s pancreas, while Heparin, a blood-thinning drug, is derived from pig and cattle intestines.8,9,10 The pericardium tissue of the cattle or the valve tissue of pigs can be used to make biological heart valves or used as patches in surgical procedures like arteriotomy.11 Additionally, gall bladders can produce gallstones, which are used in traditional Chinese medicine.12Animal by-products also have educational uses. Items such as eyes, lambs and pigs hearts, blood, and jaws are often sent to schools and universities for dissection lessons. Pigs' heads, in particular, are often sent to dentistry schools for practice operations, as the animal’s upper jaw closely mimics a human mouth.13, 14Sweets, makeup and toiletries: extractions for consumer products One of the better known uses of edible by-products is gelatine. This is a protein extracted from the bones, skin and ligaments of pigs and cattle that can be used as an ingredient in sweets, marshmallows, baking, soups, broths, sauces, shampoos, medicine capsules and even photographic paper.8Fat, primarily from cows and sheep, can be rendered into tallow, which is used in making soap and candles as well as in beauty products such as lipstick, skin balm, and healing salve.16 Collagen, found in the bones, skin and ligaments of animals, is another common by-product found in cosmetics, including anti-aging creams, lotions, serums, baby oil, colour cosmetics, and hair care products.17Lanolin, a naturally occurring fat in sheep’s wool, is used in shower gel, make-up and skincare products, while sheep’s milk is used in shower gels, skincare products and perfume. Additionally, some make-up brushes are made from “natural” bristles, meaning the bristles come from pigs, boars, or other animals.18Construction: paving roads and keeping homes warmAnimal by-products also find their way into the construction industry. For instance, chipboards can be made using albumin glue, which is produced by extracting albumin protein from animal blood.19 And recent studies have also explored the potential of using ground and calcined animal bones in cement and asphalt production.20 For example, one study attempted to use ground bones to improve the strength of asphalt.20 Meanwhile excess sheep wool is used to make insulation used to keep homes around the World warm.21Delicacies: what we eatA few edible animal by-products are transformed into regional delicacies. For instance, hoofdkaas, a Dutch dish that literally translates to “head cheese” is typically made from a pig’s head, tail and ears. These are boiled with gherkin, paprika, herbs and gelatine, ground and then pressed into a terrine, often served on bread.Blood is another by-product used in culinary traditions. In northern England, blood is used to make black pudding, while in many parts of Europe, blood sausages are a Christmas or winter speciality. For example, in Estonia verivorst (the local blood sausage) is made from pork, pig's blood, barley groats, and marjoram, and is a traditional Christmas and winter food.22Left: hoofdkaas, a Dutch delicacy made from a pig’s head, tail and ears. Right: verivorst, the national dish of Estonia. A Sausage made from pork, pig's blood, barley groats, and marjoram, and is a traditional Christmas and winter food.Are by-products used the same way across the industry? What happens to parts that do not have an immediate use largely depends on whether the animal was slaughtered in an industrial plant or a small abattoir. Industrial plants often find markets for by-products considered undesirable in Europe and are able to sell the products abroad at a premium. For example, heads and spinal columns from Danish Crown’s plants are sent to China while udders are sent to Taiwan, all for human consumption, Morten Pedersen, Danish Crown Vice President of Sustainability, told FoodUnfolded. In contrast, spinal columns removed from animals at Perrys in Eccleshall are removed by hauliers and incinerated because the small abattoir does not have access to a market that will buy the products.Industrial grade companies do not stop there in finding uses for by-products. Animal by-products, such as fatty tissue, bones and offal, that cannot be resold internationally are sent to rendering plants where the waste is converted into usable materials.23 According to Danish Crown’s Pedersen, around 6% of animal by-products from their plants are sent for rendering. These rendering plants, which exist all over Europe, produce high quality tallows, pet feed, animal feed, organic fertilisers, chemicals and alternative energy sources, such as biodiesel, biofuel and renewable fuel meat and bone meal.24, 25 But for small abattoirs it’s the same story, Hill says: “big rendering plants aren’t interested in us” because they don’t produce a big enough volume of by-products.Leftover by-products can also be sent to biogas plants to produce alternative fuel. Biogas is produced by anaerobic digestion of organic material, such as livestock waste, manure, and other scraps. In Denmark, livestock waste (most of it slurry) constitutes around 75% of the biomass used in agricultural biogas plants.26 Interest and investment in biogas production have surged in recent years after the Russian invasion of Ukraine forced Europe to reevaluate its energy supply and explore ways to become more self-sufficient.27But while large-scale companies, such as Danish Crown, have the resources to send leftover animal by-products to alternative markets, rendering plants, or for biogas production, those produced at small abattoirs often end up being discarded. Does this mean that we are wasting animal by-products?Are by-products being wasted?The easy answer is yes - where there is waste, we can always do better. However, the major players in the meat industry seem to be using most, if not all, of the edible by-products they generate. The real issue lies with small abattoirs, which are being squeezed out by the industrialised meat industry when it comes to by-products. Where small abattoirs once earned money for their by-products, many now pay for those same products to be removed and incinerated - and this is where the “waste” is being wasted.When asked about potential solutions, Danish Crown’s Pedersen told FoodUnfolded that small abattoirs could cooperate to pool together large volumes of animal by-products (both edible and not edible) to sell internationally. Hill of Perrys of Eccleshall called for greater support for small unit owners and for rendering and processing companies to accept smaller volumes of by-products with less frequent collections from small abattoirs.As consumers, we have little control of what happens to animal by-products, whether they are generated in Danish Crown’s plants or at Perrys of Eccleshall. Having said this, buying from local butchers attached to small abattoirs, accepting less popular cuts of meat and trying to find ways to incorporate offal into our diets can go some way to offsetting by-product waste.
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