Did God ever desire/require animal sacrifices?

No. God said repeatedly that he has no pleasure in animal slaughter and that he never required it. Look at: Psalm 51:16, Jeremiah 7:22, Hosea 6:6, Matthew 9:13, Isaiah 1:11, Hebrews 10:8, Psalm 40:6, Mark 12:33, and Jeremiah 32:30. For a more detailed explanation, see my blog post Mercy and Animal Sacrifice.