The Mishnah describes two types of kosher shofar:
- Rosh Hashana – a straight shofar made from a “ya’el” horn, with a gold-plated mouthpiece. Rashi says ya’el refers to a steinbok, while the Aruch says a ya’el refers to a female sheep. The Ran sides with Rashi’s definition, citing two textual proofs. He also explains that the gold-plate is not on the tip, where one places the mouth.
- Taanit (fast day) – a bent shofar made from a male animal, with a silver-plated mouthpiece. The Ran says a bent (i.e. curved) shofar is used to distinguish it from a Rosh Hashana shofar.
The Gemara explains that a shofar used for Rosh Hashana and Yom Kippur should be curved. So why did it say above “ya’el pashut” (a straight horn)? The fact is the halacha goes according to Rav Yehuda, who holds it should be bent to teach us how to bend ourselves (i.e. change ourselves).
The reason ya’el pashut was mentioned in the Mishnah was to make it clear that a bent shofar is for Rosh Hashana and Yom Kippur, but not for the Yovel. The Ran explains that a straight shofar is ideal for the Yovel because it is a sign of liberty or liberation. He then asks whether the debate between kafuf (bent) and pashut (straight) is merely a mitzvah or a mandatory requirement. Following a long give-and-take the Ran concludes that we follow the advice of Rav Levy and use a bent shofar for Rosh Hashana and Yom Kippur, however this is merely considered the preferred form of the mitzvah and not an inviolable precept. The Ran lays forth the following conclusions regarding kosher shofars:
- Any type of shofar can be used, if necessary, with two exceptions: a cow horn or a horn made of the zachrus (the bony core of an animal horn).
- A bent/curved shofar is preferred.
- A ram’s horn is ideal.
The Shiltei Giborim adds examples, saying a kosher shofar can be made from the horn of a goat or antelope, even if it’s a straight, but a ram’s horn is best, because it serves as a reminder of Akeidas Yitzchak, where Avraham Avinu sacrificed a ram in lieu of his beloved son.
As an end note, the Ran suggests that although we have established that the horns of any animal except a cow can be used, perhaps only kosher animals are acceptable. He cites Shabbos 28a, which says only a kosher animal can be used for a Maleches Shamayim (a divine endeavor), and blowing the shofar is considered a Maleches Shamayim.