2. How Do Farmed Animals Suffer?

Sentience is the ability to experience feelings, such as pain and hunger, as well as emotions, such as fear and joy. Sentient animals have the ability to suffer and also to experience pleasure.

Over the past few decades, the sentience of non-human animals and their complex emotional lives have been increasingly recognised by scientists. Animal sentience has become a field of study in its own right.

Scientists generally agree that mammals and birds are sentient — they are aware of their perceptions, experiences, and emotions. It appears that many animals have mental capacities that for a long time we thought were unique to humans. This means that we must recognise that the land animals that we raise for food — chickens, ducks, pigs, sheep, goats, cows, etc. — are sentient beings. These animals are capable of a wide range of sensations, emotions and experiences.

Until recently, much work on animal sentience focussed on mammals and birds. There is now compelling evidence that fish are sentient and can experience pain and emotions. Fairly recently, experiments have demonstrated that at the anatomical level, fish have neurons known as nociceptors, which detect potential harm, such as high temperatures and intense pressure. Fish produce the same opioids—the body’s innate painkillers—that mammals do. And their brain activity during injury is comparable to that in terrestrial vertebrates. There is also currently debate about whether certain invertebrate species including decapod crustaceans (e.g. crabs, lobsters) and cephalopods (e.g. octopuses, squids) are sentient.

Several countries include the concept of animal sentience in their laws, including France, New Zealand, Peru, Spain and Sweden. Perhaps the most comprehensive inclusion of animal sentience in law is found in the UK’s Animal Welfare (Sentience) Act, which was passed in April 2022. This was a breakthrough: it is a law that specifically recognises that all vertebrate animals (and an important selection of invertebrates) are sentient. This means that there is a moral obligation to protect their welfare.

This recognition of the sentience of animals — of their ability to suffer and to feel pleasure, and also the acknowledgement of their complex emotional lives and experiences — means that morally, as a society, we must question the many ways that humans exploit animals.

Undoubtedly, more animals are exploited for food than for any other reason. Therefore, the welfare of farmed animals is increasingly recognised as a worthy cause that deserves significant attention.

This paper broadly summarises scientific knowledge about the sentience of animals, particularly from a "welfare-aligned" perspective. You can also learn more about the sentience of animals here.