Reference for Bekhorot 33:31

אי הכי ליפלגו בחוששין לזרע האב בעלמא בפלוגתא דחנניה ורבנן

Said R'Johanan: R'Meir agrees however<span class="x" onmousemove="('comment',' Although in respect of the law of the firstling R. Meir holds that the sheep goes back to its former status.');">¹⁸</span>

Jastrow