Isaiah 1:11-16King James Version (KJV)
11 To what purpose is the multitude of your sacrifices unto me? saith the Lord: I am full of the burnt offerings of rams, and the fat of fed beasts; and I delight not in the blood of bullocks, or of lambs, or of he goats.
12 When ye come to appear before me, who hath required this at your hand, to tread my courts?
13 Bring no more vain oblations; incense is an abomination unto me; the new moons and sabbaths, the calling of assemblies, I cannot away with; it is iniquity, even the solemn meeting.
14 Your new moons and your appointed feasts my soul hateth: they are a trouble unto me; I am weary to bear them.
15 And when ye spread forth your hands, I will hide mine eyes from you: yea, when ye make many prayers, I will not hear: your hands are full of blood.
16 Wash you, make you clean; put away the evil of your doings from before mine eyes; cease to do evil
Who told you to sacrifice living animals? The Lord has been the sacrifice since before the foundation of the world. It's all internal and spiritual. When we humble ourselves and see us for what we are, make ourselves low, let the Lord teach us internally, and meditate, forget everything we think we know.... And wait patiently for truth, it's the most beautiful thing. We are to sacrifice our carnal, fleshly, egotistical nature, the beast/animal within us and die with Christ to our old selves and the resurection occurs within our hearts, creating our new selves.