You must set apart to the LORD your God every firstborn male produced by your herds and flocks. You are not to put the firstborn of your oxen to work, nor are you to shear the firstborn of your flock.
Jewish Publication Society of America Version (JPS1917) - Deuteronomy 15:19 >All the firstling males that are born of thy herd and of thy flock thou shalt sanctify unto the LORD thy God; thou shalt do no work with the firstling of thine ox, nor shear the firstling of thy flock.