Chullin 82: Mothers, Offspring and Slaughter

A new Mishna teaches us that if a mother and an offspring were sold on the same day, the person making the first purchase has the right to slaughter that animal on that day.  This prevents the other buyer from slaughtering its animal that day.  If the second person slaughtered his/her animal first regardless, then s/he prevents the owner who bough first from completing the slaughter that day.

The Tosefta explain this law.  It is understood that one who buys an animal wishes to slaughter it that day.  Thus s/he has the right to slaughter that animal before another person slaughters his/her animal. One cannot give greater rights to another person than his/her own rights regarding the animal owned.  

The Rosh rules that this Mishna's law is only enforceable when two people purchased animals from the same place.  If they bought their animals from two different sources, each has the right to slaughter their animal that they purchased "first".  Another rabbi suggests that a lottery should decide who should slaughter their animal first.