Where does all the blood from slaughtered animals go?
ASK A RESEARCHER: Enormous amounts of blood are drained at Norwegian slaughterhouses and fish farms. "Very little blood is thrown away," says a researcher.
A cow carries about 30 litres of blood, which is drained immediately after slaughter.(Photo: Cornelius Poppe / NTB)
Blood in the sauce gives a rich and delicious flavour, says a Norwegian cookbook from 1898.
Blood-based food used to be cheap and nutritious. Blood dumplings, blood sausages, blood pancakes, and pudding were typical dinner dishes in the past. But when was the last time you cooked with blood?
There's a reason blood was common in food. There's a lot of it:
A cow has about 30 litres of blood.
A pig has 7 litres of blood.
A chicken has roughly 150 millilitres of blood.
More than 300,000 cattle, 1.5 million pigs, and 75 million chickens are slaughtered in Norway each year, according to Animalia (link in Norwegian).
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Is animal blood still used for human food today?
The blood is drained from animals quickly. For larger animals, the blood vessels from the heart are cut. For chickens, the entire head is chopped off.
So, where does it all go?
"Blood is still used in certain foods, such as black pudding and blood sausages. But only a few per cent of the blood from slaughtered animals ends up in human food today," says researcher Rune Rødbotten at the food research institute Nofima.
Blood pancakes are often served with butter, sugar, syrup, berries, or bacon. Sámi blood waffles and pancakes are still on the menu in the north of Norway, but they make only a small dent in the enormous volumes of blood collected at slaughterhouses.(Photo: Wikimedia Commons / Public domain)
"Blood can be used in most meat products, such as sausages, but it gives a colour that consumers dislike," says Rødbotten.
That's not the case in Spain, where Rødbotten recently attended a conference.
"Here, they use far more blood in their cooking," he says.
However, consumer preferences are not the only reason blood is no longer widely used in Norwegian meat products.
A scandal that changed the regulations
Following the mad cow disease scandal in the UK in 1986, the regulations were changed. The outbreak happened because cows were fed meat and bone meal from other cows that had not been properly heat-treated.
Although unrelated to the use of blood in human food, it led to several regulatory changes.
"Since then, the regulations around preventing contamination in food have only become stricter," says Rødbotten.
Today, only a few slaughterhouses in Norway collect blood for human consumption, and only for short periods. The skin must be clean, and both the room and the equipment must be sterile.
"It's labour-intensive, and the investment costs in Norway are high," says Rødbotten.
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That’s why it’s easier and more profitable for slaughterhouses to sell the blood elsewhere.
Pets eat the blood
"The animal feed industry buys the blood and pays well for it," says Rødbotten.
While livestock blood can be used in feed for other livestock, its use is heavily regulated.
That's why blood from cows, sheep, and pigs often ends up as cat and dog food instead.
Rune Rødbotten believes we should eat the whole animal, including the blood.(Photo: Nina Kristiansen)
"Very little blood is thrown away. It's collected and classified as a by-product, which means it can't be used for human food," he says.
A shame that we don't eat more blood
Rødbotten himself would like to see more blood used in our food.
"It's a shame, because blood is very rich in iron, and there are many, especially women, who consume too little iron. A little blood pudding would be good for them," says Rødbotten.
He believes the regulations will eventually be changed back.
"With the growing focus on sustainability and using the whole animal, we’ll need to loosen the regulations so that blood and other by-products can be put to better use," he says.
What about fish blood?
A three-kilo fish has a little over 100 millilitres of blood. Fish blood is quite similar to the blood of mammals and humans.
When a fish is caught, its blood vessels are cut so it can bleed out. In commercial fishing and fish farms, this is required by law. Removing the blood gives whiter and cleaner fillets with better shelf life.
There has not been a tradition of eating fish blood, according to senior researcher Runar Gjerp Solstad at Nofima.
Runar Gjerp Solstad wants us to eat the whole fish, including the blood.(Photo: Nofima)
"In the past, when people ate wild-caught fish, there was probably too little blood in each fish to make it worth the effort," he says.
But things are different now. With millions of salmon slaughtered in fish farms, the amount of blood is immense.
A significant amount of blood is wasted at salmon slaughterhouses.(Photo: Gorm Kallestad / NTB)
Poured into the sea
Today, the blood is first drained from the fish and then released into the sea.
"40,000 tonnes of fish blood are thrown away every year," says Solstad.
That's enough to fill 64 swimming pools with blood.
"With such large quantities, it makes sense to explore ways to use it. Besides, blood is the only part of the salmon that isn't used today," he says.
A splash of blood in your hot chocolate
While bones, fins, and all other inedible parts of the fish are processed into animal feed, the blood is left unused.
Solstad has studied how fish blood can be incorporated into dietary supplements.
"Iron deficiency is common. If you take iron from salmon blood, it's ten times more effective than the iron salt usually used in tablets," he says.
The result of this research have been taken further by a commercial company. But Solstad believes there are more possible uses and would like us to consume more fish blood.
"We've looked at the possibility of using fish blood in traditional foods, like blood sausage and pudding. I think it’s a promising path that ensures we use the whole fish," he says.
Solstad even suggests adding a splash of blood to your hot chocolate.
"That way, you get both protein and iron," he says.
