ANIMALS USED IN PLOUGHING
Use of oxen. In Bible times oxen were used almost exclusively for ploughing. For this reason the expression "a yoke" was used by the Hebrews to mean the measure of land which a yoke of oxen could plough in a day (cf. I Samuel 14:14, and Isaiah 5:10). "Oxen" as the Hebrews used the term, meant both sexes of the animal, cows being used as well as bulls for purposes of draught, but the latter were castrated.
This explains the reason for the law specifying concerning a heifer to be used for sacrificial purposes, that it be one "upon which never came yoke" (Numbers 19:2). The law of Moses forbade ploughing with an ox and an ass yoked together (Deuteronomy 22:10). The Apostle Paul spoke of "the unequal yoke" in connection with partnership between believers and unbelievers (II Corinthians 6:14).
Today, the Arabs usually make use of oxen in ploughing, but sometimes utilize camels, and occasionally yoke together an ox and a donkey, or a camel and a donkey. [Manners And Customs of Bible Lands]