It was God who instituted and commanded the animal sacrifices. If God then says that they are an abomination to Him after He commands them to be done, then God is schitzophrenic. But, God is not schitzophrenic. The problem is not with God. Let us use a modern day anology.
Most Christian churches sing songs in their services.
Because God's people sing songs on Sunday and lives like the world on Monday. The problem is not the animal and the problem is not the songs. Animal sacrifices don't save you and singing nice songs on Sunday doesn't save you. But, a song in faith from the heart God will accept and an animal sacrifice from the heart, God will accept. Singing songs on Sunday by tradition does not praise God if there is no sincerity of heart.