Every firstborn that is born in your herd and in your flock, the male, you shall consecrate to Hashem your God; you shall not work with the firstborn of your ox, nor shear the firstborn of your flock.
English: "That is born" — A first-calving animal that has difficulty giving birth: one cuts limb by limb and throws the pieces to the dogs; but if the majority has emerged it must be buried. What is the reason? Because we read concerning it "that is born."
On the daf / in context: Once the majority of the fetus has emerged it acquires the status of a firstborn and requires burial if it dies.
Type of Learning
Derash on the verse (Chullin) — the threshold of birth for a firstborn.
What Is Learned
When the majority of a firstborn animal has emerged from the womb it is regarded as born and, if it dies, must be buried.