Srimad Bhagavatam Canto 04, Chapter 07, Text 33

SB 4.7.33

patnya ucuh
yajño ’yam tava yajanaya kena srsto
vidhvastah pasupatinadya daksa-kopat
tam nas tvam sava-sayanabha-santa-medham
yajñatman nalina-ruca drsa punihi
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
The wives of the performers of the sacrifice said: My dear Lord, this sacrifice was arranged under the instruction of Brahma, but unfortunately Lord Siva, being angry at Daksa, devastated the entire scene, and because of his anger the animals meant for sacrifice are lying dead. Therefore the preparations of the yajña have been lost. Now, by the glance of Your lotus eyes, the sanctity of this sacrificial arena may be again invoked.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
Animals were offered in sacrifice in order to give them renewed life; that was the purpose of having animals there. Offering an animal in sacrifice and giving him renewed life was the evidence of the strength of chanting mantras. Unfortunately, when Daksa’s sacrifice was devastated by Lord Siva, some of the animals were killed. (One was killed just to replace the head of Daksa.) Their bodies were lying about, and the sacrificial arena was turned into a crematorium. Thus the real purpose of yajña was lost.
Lord Visnu, being the ultimate objective of such sacrificial ceremonies, was requested by the wives of the priests to glance over the yajña arena with His causeless mercy so that the routine work of the yajña might be continued. The purport here is that animals should not be unnecessarily killed. They were used to prove the strength of the mantras and were to have been rejuvenated by the use of the mantras. They should not have been killed, as they were by Lord Siva to replace the head of Daksa with an animal’s head. It was pleasing to see an animal sacrificed and rejuvenated, and that pleasing atmosphere had been lost. The wives of the priests requested that the animals be brought back to life by the glance of Lord Visnu to make a pleasing yajña.
Srimad Bhagavatam Canto 04, Chapter 07, Text 32
Srimad Bhagavatam Canto 04, Chapter 07, Text 34