Animal (and human) sacrifices have been a terrible reality of many cultures for thousands of years. Below are excerpts from Wikipedia about the subject.
Animal sacrifice is the ritual killing of an animal as part of a religion. It is practiced by adherents of many religions as a means of appeasing a god or gods or changing the course of nature. Animal sacrifice has [been a part of] almost all cultures, from the Hebrews to the Greeks and Romans … Ancient Egyptians [and] Aztecs.
[Human sacrifice has been practiced by many cultures. The reasons include:
…death of a king, high priest or great leader; the sacrificed [humans] were supposed to serve or accompany the deceased leader in the next life…
…times of natural disaster. Droughts, earthquakes, volcanic eruptions, etc. were seen as a sign of anger or displeasure by deities, and sacrifices were supposed to lessen the [god's anger]…
The Aztecs practiced human sacrifice on an unusually large scale; a sacrifice [was] made every day to aid the sun in rising… the dedication of the great temple at Tenochtitlán [required the sacrificing of thousands [of people]….
The Phoenicians of Carthage were reputed to practice child sacrifice…, there is archaeological evidence of large numbers of children’s skeletons buried … with sacrificial animals.
Human sacrifice still happens today as an underground practice …Human sacrifice is no longer officially condoned in any country, and [is now] regarded as murder.