Why is there an animal welfare scale?
There’s reason to believe that a large number of non-human animals are sentient. An estimated 170 billion animals are farmed and killed for human consumption each year while only about 107 billion people have ever lived. To decrease the price of animal products factory farming practices have been optimised at the cost of animal welfare. This has lead to a large number of farmed animals being subjected to immense suffering. It is reasonable to consider changing our dietary habits to reduce demand for products that cause such suffering.
Michael Huemer’s Ethical Vegetarianism is a short book discussing the ethics of consuming animal products.
Are shrimp sentient? What are the harms associated with shrimp farming?
There have not been that many studies investigating whether decapod crustaceans (an order which includes shrimp) are sentient but for some species substantial evidence of sentience exists. Shrimp are farmed in greater numbers than all farmed land animals combined. In order to not risk causing a great deal of harm it is reasonable to assume that decapod crustaceans are sentient when making decisions about our diet.
Some of the welfare issues of shrimp aquaculture include eyestalk ablation which is the removal of eyestalks to increase fertility of female shrimp, spread of diseases, high stocking density and poor water quality such as insufficient level of dissolved oxygen.
Shrimp aquaculture is also not sustainable. Shrimp farming contributes to destruction of mangroves, viral disease outbreaks which affect wild animals and releasing carbon dioxide from the seafloor by using bottom trawling to catch fish who are used to produce shrimp feed.
Why does milk have such a low score?
The average annual milk yield of a US dairy cow is over 10,000 kg. In comparison slaughtering a broiler yields around 2 kg of meat. More small animals have to be raised and killed to produce the same amount of calories as from killing a larger animal. This effect is especially pronounced when comparing produce from smaller animals to milk.
Why do eggs have such a high score?
Eggs have a high harm score on the welfare scale due to the opposite effect of what causes the low score of milk. Chickens are small animals which means a relatively large number of chickens have to be used to produce the amount of eggs humans consume. Modern egg-laying hen breeds can lay over 300 eggs a year. Americans, for example, eat more than 200 eggs per person in a year.
Another factor influencing the score of eggs is the choice of cumulative elasticity factors. In the Animal Charity Evaluators’ set of factors (the default option in this tool) eggs have a high cumulative elasticity factor. This assumes that decreased consumer demand for eggs has a smaller effect on production than with other animal products.
Another noticeable difference is the high default suffering intensity factor of caged hens. Although these scores are very subjective the default values are based on what Brian Tomasik knew about the conditions of farmed animals. Egg-laying hens are one of the worst off species used by humans. Common farming practices include culling male chicks by grinding them alive, debeaking chicks without anaesthesia and keeping chickens in small cages where the stress causes them to turn to cannibalism.
Does the model consider breeder animals, fish meal, male chicks and male calves?
Although the author acknowledges that the number of these animals is significant, due to the difficulty of obtaining this data for all species included in the tool it was decided not to account for secondary deaths.
Here “secondary deaths” means the animals killed during the processes involved in factory farming whose meat/eggs/milk does not reach store shelves. For example male chicks of egg-laying hen breeds are killed shortly after birth because they do not lay eggs and are not economical to raise for meat. Another example would be fish farms where wild-caught fish are fed to carnivorous species raised on the farms.