Some useful resources on animal sentience and intelligence:
Animals are conscious and should be treated as such
Are Pigs as Smart as Dogs and Does It Really Matter?
Baby chicks do basic arithmetic and Newly hatched chicks pass maths test
Animal Emotions: Do animals think and feel?
More about Pigs: The underestimated animal
Prominent scientists sign declaration that animals have conscious awareness, just like us RELATED: The Cambridge Declaration of Consciousness