>>798816
>It's more likely a practice that slipped in the the tradition in some villages during the Ottoman rule
According to
https://en.wikipedia.org/wiki/Kourbania
there are numerous attestations of this custom from Byzantine times.
>>797790
>I hear in placed like Greece and Turkey, Orthodox Christian sacrifice goats to the Trinity, Mary, or a patron saint.
This custom is still very popular in Bulgaria. It is not, however, a sacrifice to God or to a Saint. It is a donation to the poor men in the name of God or a Saint (in Bulgarian language there is one word for sacrifice and donation). It is often done in the day of the patron saint of the Church in the town of the village, which day is considered a holiday of the whole town or village and even the poorest people have the unique chance to eat some high quality food. There are also personal kourbania in which people who want to thank God (often by survivors of an accident or disease) make this gift for fellow-men and poor men.
>How do Orthodox defend this practice?
By Matthew 25:37-40:
"Then the righteous will answer him, saying, ‘Lord, when did we see you hungry and feed you, or thirsty and give you drink?’ And the King will answer them, ‘Truly, I say to you, as you did it to one of the least of these my brothers, you did it to me.’"