Bekhorot 20: three things to remember

Ravina explains the Rabbis disregard majorities that depend on mating, leaving the pregnancy status of a bought goat in doubt.
A murky uterine discharge indicates a prior fetus, exempting subsequent births from bechor if sufficient time elapsed before conception.
Ten ma'aser-eligible kids can emerge in one year only if the mother's triplet daughters each give birth to triplets.