once krishna said

For the sake of yagna if the animal is been sacrificed its considered okay by the shastras . here are some references Verses for sacrifice of animal and eating atrāpi vidhir uktaś ca munibhir māṁsa-bhakṣaṇe | devatānāṁ pitṛṇāṁ ca bhuṅkte dattvā tu yaḥ sadā | yathā vidhi yathā śraddhaṁ na sa duṣyati bhakṣaṇāt || 12 || And in this matter of animal food, this rule has been laid down by Munis:– Whoever partakes of animal food after having first offered it duly and respectfully to the gods and the manes, is not polluted by the act.(vyadha gita adhyayA 2) Commentary Manu 5:40 - 43. Herbs, trees, cattle, birds, and (other) animals that have been destroyed for sacrifices, receive (being reborn) higher existences. On offering the honey-mixture – madhu-parka (to a guest), at a sacrifice and at the rites in honour of the Ancestors, but on these occasions only, may an animal be slain; that (rule) Manu has proclaimed. A twiceborn man who, knowing the true meaning of the Veda, slays an animal for th...