Short answers, pulled from the story.
Humphrey Primatt published the book A Dissertation on the Duty of Mercy and Sin of Cruelty to Brute Animals in 1776. His work argued that animals possess a soul and that humans have a moral duty to show them mercy.
The Society for the Prevention of Cruelty to Animals was founded in 1824 by Irish MP Richard Martin. Queen Victoria gave her blessing to the society in 1840, transforming it into the Royal Society for the Prevention of Cruelty to Animals.
The Brambell Report led to the establishment of the Farm Animal Welfare Advisory Committee in 1967 which recommended that animals require freedom to stand up, lie down, turn around, groom themselves, and stretch their limbs. These principles later became known as the Five Freedoms including freedom from thirst and hunger, freedom from discomfort, freedom from pain injury and disease, freedom to express most normal behavior, and freedom from fear and distress.
In the UK alone up to 20 million broilers each year die from the stress of catching and transporting before reaching the slaughterhouse. This stress can be measured by the high level of heart rate and its cortisol levels.
The European Union Council Directive 1999/74/EC came into effect on the 1st of January 2012. This legislation means that conventional battery cages for laying hens are now banned across the Union.
The 3R principle stands for replacement reduction and refinement and is used to lessen the use of animals in research and lessen any suffering. Researchers must meet up with the 3R's to show how they are going to put their plan into action before an ethics committee reviews the plan.