Chullin 78: Slaughter of Parent and Offspring on the Same Day

A new Mishna teaches us about oto ve'et beto, slaughtering mothers and their offspring on the same day.  These laws are interpretations of Vayikra (22:28).  Only kosher domesticated animals are discussed - not birds or wild animals.  If the offspring is slaughtered first, male or female, the rabbis agree that the Torah prohibition applies.  However, the father may or may not be included in the prohibition.  Our Mishna specifies that sanctified animals brought as sacrifices to the Temple are included as well.  

Tosafot wonder why this last question is even a question at all.  Two possible answers are offered:

• The Mishna is teaching a specific case where one is obligated to offer the Pesach sacrifice and only an offspring whose mother was slaughtered that day is available.  Instead of setting aside the prohibition for this case because of the positive commandment regarding bringing the korban, the prohibition stays in place

• The law begins with "whether it be a bull or a sheep" which separates this verse from the previous verse.  Perhaps this was done to show that it is not included in the list of rules for sanctified animals.  The Mishna must teach otherwise.