I think any introduction of "animal rights" as such would be a joke. It would be more practical to forbid mistreatment and develop standards for each sort of lifestock what is reasonable and what's necessary. It would be funny to see a prosecutor argue "you forced these animals to live in crampy quarters before you butchered them, you violated their rights!"

To be honest I think that most people like the idea of animal welfare in theory but wouldn't like paying 25-50% more for fish and meat to ensure a happy life for animals before they're dragged to the abatoir.