Firstborn of Flocks and Herds are to be offered to the Lord but eaten by the family making the offering.

Deuteronomy 15:19. “All the firstling males that come from your herd and your flock you will sanctify to the LORD* your God. You will do no work with the firstling of your ox or shear the firstling of your sheep. 20. You will eat it before the LORD* your God year by year in the place which the LORD* will choose, you and your household. 21. And if there is any blemish in it, as if it is lame, blind, or has any ill blemish, you will not sacrifice it to the LORD* your God. 22. You will eat it within your gates, the unclean and the clean will eat it alike, like the roebuck and the deer. 23. Only you will not eat its blood. You will pour it on the ground like water.”