It's been an age old practice for Hindus, especially in rural areas to offer domestic animals like Goat, Sheep to female dieties.
Like various other religious practices, animal sacrifice concept was also misunderstood and misinterpreted.
What was told in Hinduism was to get rid of some negative qualities so as to bring out "Saatvik" or Noble qualities within us.
In Hinduism, Goat represents Cowardness, Sheep represents Foolishness, Cat represents Thief like qualities, Bull represents arrogance.
It is these 4 qualities that are asked to be sacrificed before "Shakthi" so as to bring your positive qualities to the forefront.
Some have literally taken the translation and started offering the animals itself instead of the animal instincts.
Thankfully, such practices have been brought down to a large extent due to rising social awareness, but such practices have left doubts about Hinduism. Hope future generations will get to learn about the real concepts behind such practices.
Sri Rama Jayam!
Source: BrahmaSri Chaganti Pravachanam