Aśvamedha-yajñas or Gomedha-yajñas, sacrifices in which a horse or a bull is sacrificed, were not, of course, for the purpose of killing the animals. Lord Caitanya said that such animals sacrificed on the altar of yajña were rejuvenated and a new life was given to them. It was just to prove the efficacy of the hymns of the Vedas. By recitation of the hymns of the Vedas in the proper way, certainly the performer gets relief from the reactions of sins, but in case of such sacrifices improperly done under inexpert management, surely one has to become responsible for animal sacrifice. In this age of quarrel and hypocrisy there is no possibility of performing the yajñas perfectly for want of expert brāhmaṇas who are able to conduct such yajñas.
-Shrimad Bhagvatam Canto 1 Chapter 8 Verse 52, Translation and Purport

अच्छेद्योऽयमदाह्योऽयमक्ल‍ेद्योऽशोष्य एव च ।
नित्यः सर्वगतः स्थाणुरचलोऽयं सनातनः ॥ २४ ॥
This individual soul is unbreakable and insoluble, and can be neither burned nor dried. He is everlasting, present everywhere, unchangeable, immovable and eternally the same.
-BG 2.24