פירוש על עבודה זרה 31:10

This source describes the House of Rabbi [Judah Hanasi] basically bribing the Roman authorities so that they would not have to give a fatted ox to be sacrificed. The second bribe they paid was to allow them to give them a dead ox, which obviously cannot be sacrificed. Now, since they already bribed the Romans that the ox should be presented the day after their festival, what does it matter whether the ox is dead or alive? The answer has to be that they were concerned lest they hold on to the fatted ox and use it for labor prohibited on Shabbat.