Reference for Bava Kamma 108:27
אי הכי אפילו אדם ליתסר אלמה תנן אדם מותר עם כולן לחרוש ולמשוך
should be included, but that which was not subject to the sanctity of first birth<span class="x" onmousemove="('comment',' Such as horses and camels and the like. ');"><sup>37</sup></span> should not be included; the Divine Law therefore inserted also 'ox'.<span class="x" onmousemove="('comment',' To include those animals which otherwise would have been excluded; for since the species of ox is subject to the sanctity of first-born and would in no case have been excluded, its insertion being thus superfluous was surely intended to include even those animals which are not subject to the sanctity of first-born. On the other hand, birds should still be excluded since, unlike ox and ass, their carcasses do not defile, either by touching or by carrying. ');"><sup>38</sup></span>